Title: MS Windows 2000 Debug Registers Vulnerability
Severity: MODERATE
Description:
A vulnerability exists in the handling of debug registers in Windows 2000.
During a program's debugging process, it is possible to stop program execution at arbitrary places using 'breakpoints'. Breakpoints are implemented with the help of 7 registers, 'DR registers', which are part of a Windows process's thread context.
A vulnerability in Win2K allows for one process to set the DR registers in a way that will cause other processes to be affected. It is thus possible for local, unprivileged processes to essentially create breakpoints for arbitrary processes. If a process has a breakpoint set but does not have any way to handle it, it will cease to function due to a breakpoint exception. Therefore, it is possible for an unprivileged process to terminate an arbitrary process on the system.
This vulnerability could be used as a denial of service. There are more serious consequences, however. Certain system processes may maintain named pipes. These pipes have unique 'names', which may be trusted by other critical processes. If a user can cause an arbitrary process that has created such a pipe to die, it may be possible for the attacker to create a pipe with the same 'unique name' as the one trusted by other processes. Depending on the programs involved, it may be possible to elevate privileges by 'impersonating' the trusted communications channel (named pipe) of another privileged process.
Affected Products:
- Avaya DefinityOne Media Servers
- Avaya IP600 Media Servers
- Avaya S3400 Message Application Server
- Avaya S8100 Media Servers
- Microsoft Windows 2000 Advanced Server
- Microsoft Windows 2000 Advanced Server SP1
- Microsoft Windows 2000 Datacenter Server
- Microsoft Windows 2000 Datacenter Server SP1
- Microsoft Windows 2000 Professional
- Microsoft Windows 2000 Professional SP1
- Microsoft Windows 2000 Server
- Microsoft Windows 2000 Server SP1
- Microsoft Windows 2000 Terminal Services
- Microsoft Windows 2000 Terminal Services SP1
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