# T1027.002 - Obfuscated Files or Information: Software Packing ## [Description from ATT&CK](https://attack.mitre.org/techniques/T1027/002)
Adversaries may perform software packing or virtual machine software protection to conceal their code. 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. 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) Utilities used to perform software packing are called packers. Example packers are MPRESS and UPX. A more comprehensive list of known packers is available, but adversaries may create their own packing techniques that do not leave the same artifacts as well-known packers to evade defenses.(Citation: Awesome Executable Packing)
## Atomic Tests - [Atomic Test #1 - Binary simply packed by UPX (linux)](#atomic-test-1---binary-simply-packed-by-upx-linux) - [Atomic Test #2 - Binary packed by UPX, with modified headers (linux)](#atomic-test-2---binary-packed-by-upx-with-modified-headers-linux) - [Atomic Test #3 - Binary simply packed by UPX](#atomic-test-3---binary-simply-packed-by-upx) - [Atomic Test #4 - Binary packed by UPX, with modified headers](#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 **auto_generated_guid:** 11c46cd8-e471-450e-acb8-52a1216ae6a4 #### Inputs: | Name | Description | Type | Default Value | |------|-------------|------|---------------| | bin_path | Packed binary | path | PathToAtomicsFolder/T1027.002/bin/linux/test_upx| #### Attack Commands: Run with `sh`! ```sh cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin ``` #### Cleanup Commands: ```sh 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 **auto_generated_guid:** f06197f8-ff46-48c2-a0c6-afc1b50665e1 #### Inputs: | Name | Description | Type | Default Value | |------|-------------|------|---------------| | bin_path | Packed binary | path | PathToAtomicsFolder/T1027.002/bin/linux/test_upx_header_changed| #### Attack Commands: Run with `sh`! ```sh cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin ``` #### Cleanup Commands: ```sh 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 **auto_generated_guid:** b16ef901-00bb-4dda-b4fc-a04db5067e20 #### Inputs: | Name | Description | Type | Default Value | |------|-------------|------|---------------| | bin_path | Packed binary | path | PathToAtomicsFolder/T1027.002/bin/darwin/test_upx| #### Attack Commands: Run with `sh`! ```sh cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin ``` #### Cleanup Commands: ```sh 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 **auto_generated_guid:** 4d46e16b-5765-4046-9f25-a600d3e65e4d #### Inputs: | Name | Description | Type | Default Value | |------|-------------|------|---------------| | bin_path | Packed binary | path | PathToAtomicsFolder/T1027.002/bin/darwin/test_upx_header_changed| #### Attack Commands: Run with `sh`! ```sh cp #{bin_path} /tmp/packed_bin && /tmp/packed_bin ``` #### Cleanup Commands: ```sh rm /tmp/packed_bin ```