T1045.md

T1045 - Software Packing

Description from ATT&CK

Software packing is a method of compressing or encrypting an executable. Packing an executable changes the file signature in an attempt to avoid signature-based detection. Most decompression techniques decompress the executable code in memory.

Utilities used to perform software packing are called packers. Example packers are MPRESS and UPX. A more comprehensive list of known packers is available, (Citation: Wikipedia Exe Compression) but adversaries may create their own packing techniques that do not leave the same artifacts as well-known packers to evade defenses.

Adversaries may use virtual machine software protection as a form of software packing to protect their code. Virtual machine software protection translates an executable's original code into a special format that only a special virtual machine can run. A virtual machine is then called to run this code.(Citation: ESET FinFisher Jan 2018)

Atomic Tests

• Atomic Test #1 - Binary simply packed by UPX (linux)

• Atomic Test #2 - Binary packed by UPX, with modified headers (linux)

• Atomic Test #3 - Binary simply packed by UPX

• Atomic Test #4 - Binary packed by UPX, with modified headers

Atomic Test #1 - Binary simply packed by UPX (linux)

Copies and then runs a simple binary (just outputting "the cake is a lie"), that was packed by UPX. No other protection/compression were applied.

Supported Platforms: Linux

Inputs:

Name	Description	Type	Default Value
bin_path	Packed binary	Path	PathToAtomicsFolder/T1045/bin/linux/test_upx

Attack Commands: Run with sh!

cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin

Cleanup Commands:

rm /tmp/packed_bin

Atomic Test #2 - Binary packed by UPX, with modified headers (linux)

Copies and then runs a simple binary (just outputting "the cake is a lie"), that was packed by UPX.

The UPX magic number (0x55505821, "UPX!") was changed to (0x4c4f5452, "LOTR"). This prevents the binary from being detected by some methods, and especially UPX is not able to uncompress it any more.

Supported Platforms: Linux

Inputs:

Name	Description	Type	Default Value
bin_path	Packed binary	Path	PathToAtomicsFolder/T1045/bin/linux/test_upx_header_changed

Attack Commands: Run with sh!

cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin

Cleanup Commands:

rm /tmp/packed_bin

Atomic Test #3 - Binary simply packed by UPX

Copies and then runs a simple binary (just outputting "the cake is a lie"), that was packed by UPX. No other protection/compression were applied.

Supported Platforms: macOS

Inputs:

Name	Description	Type	Default Value
bin_path	Packed binary	Path	PathToAtomicsFolder/T1045/bin/darwin/test_upx

Attack Commands: Run with sh!

cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin

Cleanup Commands:

rm /tmp/packed_bin

Atomic Test #4 - Binary packed by UPX, with modified headers

Copies and then runs a simple binary (just outputting "the cake is a lie"), that was packed by UPX.

The UPX magic number (0x55505821, "UPX!") was changed to (0x4c4f5452, "LOTR"). This prevents the binary from being detected by some methods, and especially UPX is not able to uncompress it any more.

Supported Platforms: macOS

Inputs:

Name	Description	Type	Default Value
bin_path	Packed binary	Path	PathToAtomicsFolder/T1045/bin/darwin/test_upx_header_changed

Attack Commands: Run with sh!

cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin

Cleanup Commands:

rm /tmp/packed_bin