F5 BIG-IP APM Malware Injects a PHP Web Shell Into Memory, Evading Disk Scans

F5 BIG-IP APM Malware Injects a PHP Web Shell Into Memory, Evading Disk Scans Swati KhandelwalSep 09, 2026Malware / Web Security Malware linked to break-ins at F5 BIG-IP Access Policy Manager appliances hides a PHP web shell in memory instead of in a file on disk, Sophos said in an analysis published on September 7. When Apache loads any of the three appliances' own PHP scripts, the malware adds the web shell to the copy held in memory, so a check of the file on disk can come back clean. Those three scripts are the same ones F5 pointed customers to in March, when it said changes to them alone do not show a break-in. A web shell is usually…