Software Engineering Institute

The Microsoft WINS service maps IP addresses to NETBIOS computer names. WINS servers share information via a server-to-server replication protocol that operates on TCP port 42. Connection information for replication peers is stored in a data structure called the association context. Insufficient validation of the buffer where the association context data structure is written allows a heap-based buffer overflow to occur. If a remote attacker supplies a specially crafted replication packet to a vulnerable WINS server, that attacker may be able to exploit the buffer overflow to write arbitrary data to WINS server process memory.

According to Microsoft Knowledge Base Article 890710:

This security issue affects Microsoft Windows NT 4.0 Server, Microsoft Windows NT Server 4.0 Terminal Server Edition, Windows 2000 Server, and Windows Server 2003. Windows 2000 Professional, Windows XP and Windows Millennium Edition (ME) are not affected by this vulnerability.

By default, WINS is not installed on Windows NT Server 4.0, Windows NT Server 4.0 Terminal Server Edition, Windows 2000 Server, or Windows Server 2003. By default, WINS is installed and running on Microsoft Small Business Server 2000 and Microsoft Windows Small Business Server 2003. By default, on all versions of Microsoft Small Business Server, the WINS component communication ports are blocked from the Internet, and WINS is available only on the local network.

A remote attacker may be able to execute arbitrary code with SYSTEM privileges or cause a denial-of-service condition.

Apply Patch

Microsoft has released Microsoft Security Bulletin MS04-045 to address this issue.

Consider Workarounds in MS04-045

• Removing the WINS service if it is not needed
• Blocking TCP and UDP port 42
• Using IPSec as a communication protocol between WINS servers