Software Engineering Institute

There is a buffer overflow vulnerability in the Microsoft Windows Messenger service. This could allow an attacker to execute arbitrary code with System privileges. Microsoft recommends immediately disabling the Messenger service and evaluating the need for the patch. For more information, see Microsoft Security Bulletin MS03-043. This vulnerability affects virtually all recent versions of Windows with the exception of Microsoft Windows Millennium Edition. On Windows Server 2003, the Messenger service is disabled by default; however, if it is enabled the server is vulnerable to compromise.

An attacker can run arbitrary code with Local System privileges.

Disable the Windows messenger service and evaluate the need to apply the patch. to disable the Messenger service, follow these steps as provided by Microsoft:

1. Click Start , and then click Control Panel (or point to Settings , and then click Control Panel ).
2. Double-click Administrative Tools .
3. Double-click Services .
4. Double-click Messenger .
5. In the Startup type list, click Disabled .
6. Click Stop , and then click OK .

As a general rule, and as a partial workaround to this problem, block ports 137 through 139 and UDP broadcast packets at your network perimeter and/or at the host level. This will limit the ability of external attackers to reach vulnerable systems.