Introducing sedexp: A Covert Linux Malware Targeting udev Rules

Stroz Friedberg identified sedexp, a Linux malware that persists via a novel udev rule technique. The activity has been ongoing since at least 2022, with low sandbox detections and a financially motivated focus on credit card scraping. #sedexp #creditcardscraping

Keypoints

  • Stroz Friedberg identified sedexp using a novel Linux persistence technique via udev rules.
  • The malware has been active since at least 2022 and shows low detection in online sandboxes.
  • It leverages a udev rule to persist by executing on device events, such as /dev/random.
  • The identified udev rule triggers when /dev/random is loaded, enabling execution at reboot.
  • Sedexp features include reverse shell capabilities and memory manipulation to hide its presence.
  • The malware is associated with financially motivated threat actors focusing on credit card scraping.
  • Organizations should enhance detection capabilities and conduct thorough forensic analysis.

MITRE Techniques

  • [T1547] Persistence – Udev rules to maintain persistence on Linux systems. Quote: ‘Utilizes udev rules to maintain persistence on Linux systems.’
  • [T1071] Command and Control – Reverse shell for remote access. Quote: ‘The malware includes a reverse shell, allowing the threat actor to maintain control over the compromised system.’
  • [T1027] Obfuscated Files or Information – Memory manipulation to hide its presence. Quote: ‘memory manipulation to hide any file containing the string “sedexp” from commands like ls or find.’

Indicators of Compromise

  • [SHA256] Sample hashes – 43f72f4cdab8ed40b2f913be4a55b17e7fd8a7946a636adb4452f685c1ffea02, 94ef35124a5ce923818d01b2d47b872abd5840c4f4f2178f50f918855e0e5ca2, b981948d51e344972d920722385f2370caf1e4fac0781d508bc1f088f477b648

Read more: https://www.aon.com/en/insights/cyber-labs/unveiling-sedexp