Title: NT CSRSS Worker Thread Exhaustion Vulnerability
Severity: LOW
Description:
Worker threads in CSRSS.exe (the Client Server Runtime SubSystem, aka the Win32 Subsystem) that are waiting for user input remain occupied until they get that input. If all threads (default 16) are simultaneously waiting for input, the system will hang until it is received. This condition will lead to a Denial of Service, and could be caused by malicious or defective code in a service or program.
Affected Products:
- Microsoft Windows NT 4.0
- Microsoft Windows NT 4.0 SP1
- Microsoft Windows NT 4.0 SP2
- Microsoft Windows NT 4.0 SP3
- Microsoft Windows NT 4.0 SP4
- Microsoft Windows NT 4.0 SP5
- Microsoft Windows NT Enterprise Server 4.0
- Microsoft Windows NT Enterprise Server 4.0 SP1
- Microsoft Windows NT Enterprise Server 4.0 SP2
- Microsoft Windows NT Enterprise Server 4.0 SP3
- Microsoft Windows NT Enterprise Server 4.0 SP4
- Microsoft Windows NT Enterprise Server 4.0 SP5
- Microsoft Windows NT Server 4.0
- Microsoft Windows NT Server 4.0 SP1
- Microsoft Windows NT Server 4.0 SP2
- Microsoft Windows NT Server 4.0 SP3
- Microsoft Windows NT Server 4.0 SP4
- Microsoft Windows NT Server 4.0 SP5
- Microsoft Windows NT Terminal Server 4.0
- Microsoft Windows NT Terminal Server 4.0 SP1
- Microsoft Windows NT Terminal Server 4.0 SP2
- Microsoft Windows NT Terminal Server 4.0 SP3
- Microsoft Windows NT Terminal Server 4.0 SP4
- Microsoft Windows NT Terminal Server 4.0 SP5
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Workstation 4.0 SP1
- Microsoft Windows NT Workstation 4.0 SP2
- Microsoft Windows NT Workstation 4.0 SP3
- Microsoft Windows NT Workstation 4.0 SP4
- Microsoft Windows NT Workstation 4.0 SP5
References:
- Microsoft: Exceeding MaxRequestThreads May Cause Windows NT to Hang
- Microsoft: Frequently Asked Questions: Microsoft Security Bulletin (MS99-021)
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