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Malware hides web shell in F5 BIG-IP APM memory

Security researchers report that new malware infecting F5 BIG-IP Access Policy Manager appliances installs a web shell directly into server memory, bypassing standard file-based detection methods. The attack exploits a vulnerability (CVE-2025-53521) that F5 reclassified as remote code execution in March 2026. The exploit does not require user authentication. Both installers affecting the Apache binary and the in-memory web shell have been analyzed, but no victims are named.

Why it mattersSystems controlling access to sensitive data are at risk, and attackers can bypass standard defenses. The default methods administrators use may not detect infected devices unless memory is analyzed.

Sources covering this

The Hacker NewsF5 BIG-IP APM Malware Injects a PHP Web Shell Into Memory, Evading Disk Scans7:36 AMHelp Net SecurityHackers deploy Linux rootkit on F5 BIG-IP APM devices, hiding web shell in memory11:05 AM
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