Windows 2000 and XP systems running as terminal servers can be crashed by local users. This can be done via RDP (Remote Desktop Protocol) or Citrix ICA Clients.

A user needs to log in and open %SYSTEMROOT%\SYSTEM32\MSGINA.DLL with exclusive read access. Then the user should open a new connection to the server, the user will then get a warning dialog asking him to restart the system.

This only affect terminal server systems. Windows systems running as normal workstations and servers are not vulnerable.

Solution
It is possible to remove the permissions for "Power Users", "Users" and "Everyone", this however may give complications on XP systems. We recommend that you test this solution before applying it to production systems.
Further details available to Secunia VIM customers

Provided and/or discovered by
Jonathan Hunter

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