[ SOURCE: http://www.secureroot.com/security/advisories/9768316165.html ]

Title: Microsoft Windows NT 4.0 RAS Administration Registry Key

Vulnerability

BID: 2064

Published: December 06, 2000

Vulnerable: Microsoft Windows NT 4.0

Microsoft Windows NT Terminal Server



Description:



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 enabled by default).



RAS is not installed by default on Windows NT 4.0.



Solutions:



Microsoft has released the following tool which corrects the registry key

value (this tool also corrects the registry values for other vulnerabilities

discussed in Microsoft Security Bulletin MS00-095). Please see Frequently

Asked Questions (Microsoft Security Bulletin MS00-095) under "Credit" for

details in regards to proper usage of the tool:



Microsoft patch Q265714i

http://download.microsoft.com/download/winntsp/Patch/Q266794/NT4/EN-US/Q265714i.EXE

Intel



Credit:



Discovered by Milan Dadok and publicized in a Microsoft Security Bulletin

(MS00-095) on December 6, 2000.



Reference:



http://www.securityfocus.com/bid/2064

http://www.microsoft.com/technet/security/bulletin/ms00-095.asp

http://www.microsoft.com/technet/security/bulletin/fq00-095.asp



--

Elias Levy

SecurityFocus.com

http://www.securityfocus.com/

Si vis pacem, para bellum