T1027.003: Steganography

Adversaries may use steganography techniques in order to prevent the detection of hidden information. Steganographic techniques can be used to hide data in digital media such as images, audio tracks, video clips, or text files.

Duqu was an early example of malware that used steganography. It encrypted the gathered information from a victim's system and hid it within an image before exfiltrating the image to a C2 server.

By the end of 2017, a threat group used Invoke-PSImage to hide PowerShell commands in an image file (.png) and execute the code on a victim's system. In this particular case the PowerShell code downloaded another obfuscated script to gather intelligence from the victim's machine and communicate it back to the adversary.

Positive Technologies products that cover the technique

MaxPatrol SIEM knowledge base

mitre_attck_defense_evasion: PT-CR-2060: Powershell_Execution_From_Image: The Invoke-PSImage utility was used to run a PowerShell script embedded in an image

Detection

IDDS0022Data source and componentFile: File MetadataDescription

Detection of steganography is difficult unless artifacts are left behind by the obfuscation process that are detectable with a known signature. Look for strings or other signatures left in system artifacts related to decoding steganography.