MS02-024: Authentication Flaw in Windows Debugger can Lead to Elevated Privileges

Thanks xStainDx and everyone who sent us an email about the heads up on this.

Date: 22 May 2002

Impact: Elevation of Privilege

Max Risk: Critical

Affected Software:

Microsoft Windows NT 4.0
Microsoft Windows NT 4.0 Terminal Server Edition
Microsoft Windows 2000

The Windows debugging facility provides a means for programs to perform diagnostic and analytic functions on applications as they are running on the operating system. One of these capabilities allows for a program, usually a debugger, to connect to any running program, and to take control of it. The program can then issue commands to the controlled program, including the ability to start other programs. These commands would then execute in the same security context as the controlled program.

There is a flaw in the authentication mechanism for the debugging facility such that an unauthorized program can gain access to the debugger. A vulnerability results because an attacker can use this to cause a running program to run a program of her choice. Because many programs run as the operating system, this means that an attacker can exploit this vulnerability to run code as the operating system itself. She could take any action on the system including deleting data, adding accounts with administrative access, or reconfiguring the system.

A successful attack requires the ability to logon interactively to the system, either at the console or through a terminal session. Also, an a successful attack requires the introduction of code to exploit this vulnerability. Because best practices recommends restricting the ability to logon interactively on servers, this issue most directly affects client systems and terminal servers.

View: Microsoft Security Bulletin ID MS02-024