This is not surprising, considering the number of Pulse Secure VPNs that have not yet been patched over six months after a fix was made available, despite Pulse Secure executives saying that they have “worked aggressively” to get customers to patch that vulnerability. And given that vulnerable Pulse Secure servers have been targeted now for ransomware attacks, the same will likely be true for unprotected Citrix VPN servers — especially since last week, proof-of-concept exploits of the vulnerability began to appear, including at least two published on GitHub, as ZDNet’s Catalin Cimpanu reported.“The vulnerability allows the remote execution of commands in just two HTTP requests, thanks to a directory traversal bug in the implementation of the gateway’s Web interface,” the report adds. “The attacks use a request for the directory ‘/vpn/../vpns/’ to fool the Apache Web server on the gateway to point to the ‘/vpns/’ directory without authentication. The attacks then inject a command based on the template returned from the first request.”
You can check for the vulnerability here.