New 'Plague' PAM Backdoor Exposes Critical Linux Systems to Silent Credential Theft
Aug 02, 2025
Threat Detection / SSH Security
Cybersecurity researchers have flagged a previously undocumented Linux backdoor dubbed Plague that has managed to evade detection for a year. "The implant is built as a malicious PAM (Pluggable Authentication Module), enabling attackers to silently bypass system authentication and gain persistent SSH access," Nextron Systems researcher Pierre-Henri Pezier said . Pluggable Authentication Modules refers to a suite of shared libraries used to manage user authentication to applications and services in Linux and UNIX-based systems. Given that PAM modules are loaded into privileged authentication processes, a rogue PAM can enable theft of user credentials, bypass authentication checks, and remain undetected by security tools. The cybersecurity company said it uncovered multiple Plague artifacts uploaded to VirusTotal since July 29, 2024, with none of them detected by antimalware engines as malicious. What's more, the presence of several samples signals active developme...
