PGP Security PGPfire 7.1 for Windows alters the system's TCP/IP stack and modifies packets in ICMP error messages in a way that allows remote attackers to determine that the system is running PGPfire.

BID:3961 | URL:http://www.securityfocus.com/bid/3961 | BUGTRAQ:20020125 Identifying PGP Corporate Desktop 7.1 with PGPfire Personal Desktop Firewall installed (no need to be enabled) on Microsoft Windows Based OSs | URL:http://online.securityfocus.com/archive/1/252407 | XF:pgpfire-icmp-fingerprint(8008) | URL:http://www.iss.net/security_center/static/8008.php