Checkpoint Firewall-1 Valid Username Vulnerability

Checkpoint Firewall-1 is a popular firewall package available from Checkpoint Software Technologies. A vulnerability exists in Firewall-1 whereby an attacker can determine a valid username by the response given by the firewall to authentication requests (port 259 on the firewall) from a remote client.

Upon connecting to the firewall, the attacker enters a username and password. If the username and password are invalid, the firewall will respond with "<username> not found". If the username is valid, and the password is invalid, the firewall will respond with "Access denied by Firewall-1 authentication".

Upon successfully determining a valid username, a remote attacker could then attempt a brute force or password grinding attack to determine the password for the valid username. If successful, an attacker could then gain access to the firewall based on that user's privileges.


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