Fortinet Warns Attackers Retain FortiGate Access Post-Patching via SSL-VPN Symlink Exploit
Apr 11, 2025
Network Security / Vulnerability
Fortinet has revealed that threat actors have found a way to maintain read-only access to vulnerable FortiGate devices even after the initial access vector used to breach the devices was patched. The attackers are believed to have leveraged known and now-patched security flaws, including, but not limited to, CVE-2022-42475 , CVE-2023-27997 , and CVE-2024-21762 . "A threat actor used a known vulnerability to implement read-only access to vulnerable FortiGate devices," the network security company said in an advisory released Thursday. "This was achieved via creating a symbolic link connecting the user file system and the root file system in a folder used to serve language files for the SSL-VPN." Fortinet said the modifications took place in the user file system and managed to evade detection, causing the symbolic link (aka symlink) to be left behind even after the security holes responsible for the initial access were plugged. This, in turn, enabled the threa...