Software Engineering Institute

The Private Communications Transport (PCT) protocol is part of the Microsoft Secure Sockets Layer (SSL) library. A buffer overflow vulnerability exists in the PCT that could allow a remote attacker to execute arbitrary code on the system. Only systems with SSL enabled would be vulnerable to exploitation. Microsoft has listed the following mitigating factors:

• Only systems that have enabled SSL are affected, typically only server systems. SSL support is not enabled by default on any of the affected systems. However, SSL is generally used on Web servers to support electronic commerce programs, on-line banking, and other programs that require secure communications.
• Windows Server 2003 is only vulnerable to this issue if an administrator has manually enabled PCT (even if SSL has been enabled).
• In some situations, the Web Publishing features of ISA Server 2000 or Proxy Server 2.0 can successfully block attempts to exploit this vulnerability. Testing has shown that the Web publishing features of ISA Server 2000, with Packet Filtering enabled and all Packet Filtering options selected can successfully block this attack with no noticeable side effects. Proxy Server 2.0 also successfully blocks this attack. However, until the security update is applied on the Proxy Server 2.0 system, this attack causes Proxy Server 2.0 Web services to stop responding and the system must be restarted.
• Firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed.

• Windows NT 4.0
• Windows 2000
• Windows XP
• Windows Server 2003

A remote attacker may be able to execute arbitrary code on the system.

Apply a patch from the vendor
Microsoft Security Bulletin MS04-011 contains patch information to resolve this issue.