SMS: Simultaneous Attempts to Remote Control May Cause Errors

• Microsoft Systems Management Server, version 1.2

SYMPTOMS

Windows NT Server Remote Control (Wuser32.exe) may fail if multiple Systems Management Server administrators attempt to take control at the same time. When Remote Control fails, the "Quick Windows Viewer" on the controlling computer running Systems Management Server will appear to stop responding, and Wuser32.exe may cause an error to occur on the client computer running Windows NT Workstation.

   WUSER32.exe Application Error:

   The Instruction at "0x77a835e1" referenced memory at "0x21270028". The
   memory could not be "read".
   Click on OK to terminate the application.
   Click on CANCEL to debug the application.

CAUSE

Windows NT Server Remote Control only allows one computer running Systems Management Server to control the client at a time. If multiple computers running Systems Management Server attempt to control the client, Wuser32.exe initially accepts the connections, starts to verify permissions, and then disconnects the additional Systems Management Server connections because it is already being controlled.

When a Systems Management Server connection is disconnected, Wuser32.exe parses through a list of security contexts held for Systems Management Server connections. If a security context has been inactive in the list for more than one minute, Wuser32.exe frees the context.

When the Systems Management Server administrator that currently has control of the workstation attempts to perform a remote task in the "Quick Windows Viewer", Wuser32.exe on the client computer running Windows NT Workstation looks up the security context for that Systems Management Server connection to verify permissions. If the Systems Management Server administrator's security context was freed during the connection termination of another computer running Systems Management Server, Wuser32.exe passes an invalid security context to Windows NT Server. The invalid security context causes Wuser32.exe to cause an access violation (AV) and the "Quick Windows Viewer" will appear to stop responding.

RESOLUTION

To resolve this problem, obtain the hotfix mentioned below. With the hotfix, Wuser32.exe was modified to cleanup inactive security contexts without releasing the active Systems Management Server administrator's security context.

STATUS

Microsoft has confirmed this to be a problem in Systems Management Server version 1.2. This problem was corrected in the latest Microsoft Systems Management Server 1.2 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K