Software Engineering Institute

In general terms, a mutex is an object used to control access to a resource (e.g. a printer, disk, segment of memory, data structure, etc.) so that only a single "consumer" (e.g. a process or program) can have access to the resource at any one time. That is, it enforces a policy of mutual exclusion between would-be consumers of a resource, typically so that access to the resource can by properly synchronized. A process that has acess to a resource controlled by a mutex is said to have locked the mutex. A process that "wants" a resource locked by another process is said to be waiting on the mutex, or waiting on a locked mutex.

Microsoft Windows NT 4.0 and Microsoft Windows NT 4.0, Terminal Server Edition uses a mutex named Winsock2ProtocolCatalogMutex to control access to resources required for NT networking to function properly. On unpatched versions of Windows, the mutex is protected inappropriately so that ordinary users can disable access to the mutex by changing the ACL on the mutex , or lock the mutex indefinitely. In either case, the intruder can effectively disable network access on that machine.

Intruders who can log in locally can effectively disable network access for the machine.

Apply a patch as described in MS01-003.