Microsoft Windows NT 4.0 RAS Administration Registry Key Vulnerability

The registry key in Windows NT 4.0 that handles the administration of Remote Access Service (RAS) third-party tools is not properly configured to deny write access to unprivileged users. Such lenient permissions assigned to this particular registry key would allow any user that could log on locally to a system with a RAS server installed to modify the value of the key to an arbitrary DLL file that would be executed upon startup of RAS. The DLL in the RAS registry key is run under LocalSystem privileges. Therefore, the malicious user would be able to perform any action under the LocalSystem security context which would basically yield full control over the local machine. The location of the RAS registry key is HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\RAS. This vulnerability could be exploited remotely if the Winreg key was enabled to allow remote access to the registry (Winreg is disabled by default in Windows NT Server and enabled by default in Windows NT Workstation).

RAS is not installed by default on Windows NT 4.0.


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