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FP fix: attachment_html_smuggling_atob.yml #1125

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merged 9 commits into from
Dec 21, 2023
Merged

FP fix: attachment_html_smuggling_atob.yml #1125

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d83d236
FP fix: attachment_html_smuggling_atob.yml
aidenmitchell Dec 13, 2023
a430dd2
Adding high trust
aidenmitchell Dec 13, 2023
469b418
Changing string check to regex
aidenmitchell Dec 13, 2023
d322fd0
Update attachment_html_smuggling_atob.yml
aidenmitchell Dec 13, 2023
3b354d5
Adding additional atob checks
aidenmitchell Dec 13, 2023
c2c6225
Update attachment_html_smuggling_atob.yml
aidenmitchell Dec 13, 2023
53d5718
Merge branch 'main' into aiden.fix.atob
morriscode Dec 18, 2023
9561518
Merge branch 'main' into aiden.fix.atob
morriscode Dec 20, 2023
38714f4
Merge branch 'main' into aiden.fix.atob
rw-access Dec 21, 2023
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23 changes: 21 additions & 2 deletions detection-rules/attachment_html_smuggling_atob.yml
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
name: "Attachment: HTML smuggling with atob and high entropy"
description: |
Recursively scans files and archives to detect HTML smuggling techniques.
Recursively scans files and archives to detect HTML smuggling techniques using Javascript atob functions.
references:
- "https://delivr.to/payloads?id=7dbf0d83-1557-4345-bf67-d18c4256b0c1"
type: "rule"
Expand All @@ -24,7 +24,13 @@ source: |
// usage: document['write'](atob)
or any(.scan.strings.strings, strings.ilike(., "*document*write*atob*"))
// usage: some_var = atob();
or any(.scan.strings.strings, strings.ilike(., "*=*atob*;"))
or any(.scan.strings.strings, regex.icontains(., "=.?atob.*;"))
// usage: atob(atob
or any(.scan.strings.strings, strings.ilike(., "*atob?atob*"))
// usage: eval(atob)
or any(.scan.strings.strings, strings.ilike(., "*eval?atob*"))
// usage: atob(_0x)
or any(.scan.strings.strings, strings.ilike(., "*atob(?0x*"))
// usage: obfuscating "atob"
or any(.scan.javascript.identifiers, strings.ilike(., '*ato\u0062*'))
// usage: document.head.insertAdjacentHTML("beforeend", atob(...
Expand All @@ -37,6 +43,19 @@ source: |
)
)
)
// negate highly trusted sender domains unless they fail DMARC authentication
and (
(
sender.email.domain.root_domain in $high_trust_sender_root_domains
and (
any(distinct(headers.hops, .authentication_results.dmarc is not null),
strings.ilike(.authentication_results.dmarc, "*fail")
)
)
)
or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)

attack_types:
- "Credential Phishing"
- "Malware/Ransomware"
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