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  3. Microsoft ISA Server HTTP Request Smuggling Vulnerability

Microsoft ISA Server HTTP Request Smuggling Vulnerability

Risk

High

Date Discovered

June 14, 2005

Description

Microsoft Internet Security and Acceleration (ISA) server is reported prone to a HTTP request smuggling attack. The vendor reports that Microsoft ISA server fails to correctly handle an invalid HTTP request that contains multiple 'Content-Length' values in an invalid HTTP header. A remote attacker may exploit this issue to launch cache poisoning or content-restriction bypass attacks against the affected server.

Technologies Affected

  • Microsoft ISA Server 2000
  • Microsoft ISA Server 2000 Enterprise Edition
  • Microsoft ISA Server 2000 Enterprise Edition SP1
  • Microsoft ISA Server 2000 Enterprise Edition SP2
  • Microsoft ISA Server 2000 FP1
  • Microsoft ISA Server 2000 SP1
  • Microsoft ISA Server 2000 SP2

Recommendations

Deploy network intrusion detection systems to monitor network traffic for malicious activity.

Flag on anomalous HTTP requests that contain two 'Content-length' values. Audit logs regularly and adjust policies according to results.
Microsoft has released a fix to address this issue.

Credits

Steve Orrin of Watchfire is credited with the discovery of this issue.
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Disclaimer
The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
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