Malicious Windows Executable Hidden in JPEG Image via Steganography and Base64 Obfuscation

Malicious Windows Executable Hidden in JPEG Image via Steganography and Base64 Obfuscation

This article explains the process of analyzing a hidden payload within an image file using both static and dynamic methods. It highlights the use of specific tools to decode embedded data and confirms the payload is a .NET DLL with matching SHA256 hashes. #Steganography #Xavier #PEfile #JPEG #Base64

Keypoints

  • Dynamic analysis revealed a JPEG image download containing embedded data.
  • Tools like jpegdump.py help identify data appended after the End Of Image (EOI) marker.
  • The payload includes a Base64-encoded string starting with the MZ header, indicating a PE file.
  • An unusual ‘@’ character in the Base64 string is a substitute for ‘A’.
  • The SHA256 hash of the decoded payload matches the published hash for the .NET DLL.

Read More: https://isc.sans.edu/diary/32048