A new cyber espionage campaign is underway in North Africa, featuring a custom backdoor called Stealth Soldier. Cybersecurity company Check Point has identified the backdoor as part of a set of highly-targeted attacks. Stealth Soldier primarily functions as a surveillance tool, capable of conducting activities such as file exfiltration, screen and microphone recording, keystroke logging, and browser information theft.
The attackers behind the ongoing operation have employed command-and-control servers that mimic websites associated with the Libyan Ministry of Foreign Affairs. The campaign traces back to artifacts dating as early as October 2022. The initial stage of the attacks involves the download of fake downloader binaries, delivered through social engineering tactics, which act as a conduit for retrieving the Stealth Soldier backdoor. Simultaneously, a decoy empty PDF file is displayed to mislead the target.
Stealth Soldier is a modular implant that enables surveillance capabilities through various means. It collects directory listings and browser credentials, records keystrokes, captures screenshots, uploads files, and executes PowerShell commands. Check Point discovered three versions of the backdoor, indicating that it is actively maintained by its operators. Some components of the malware are no longer retrievable, but the screen capture and browser credential stealer plugins were found to be inspired by open source projects on GitHub.
Interestingly, the infrastructure used by the Stealth Soldier campaign overlaps with infrastructure associated with a previous phishing campaign called Eye on the Nile, which targeted Egyptian journalists and human rights activists in 2019. This suggests a possible re-appearance of the same threat actor, indicating a focus on surveillance against Egyptian and Libyan targets.
Check Point warns that due to the modularity of the malware and the use of multiple stages of infection, the attackers are likely to continue evolving their tactics and deploying new versions of the Stealth Soldier backdoor in the near future.