Microsoft IIS FrontPage Server Extensions and ASP.NET ISAPI filter error handling denial of service
| iis-isapi-filter-error-dos (8800) |  Medium Risk |
Description:
Microsoft Internet Information Server (IIS) is vulnerable to a denial of service attack, caused by the incorrect handling of an error that occurs if one of the ISAPI (Internet Services Application Programming Interface) filters included with FrontPage Server Extensions (FPSE) and ASP.NET receives a URL that exceeds the length specified for that particular filter. If a remote attacker sends a request with an invalid URL length that triggers this error, the affected ISAPI filter sets the URL to a null value before returning an error response to the requesting client. Before sending this error response, IIS attempts to use this URL, which would cause an access violation to occur, resulting in the IIS service abnormally terminating.
Consequences:
Denial of Service
Remedy:
Apply the appropriate patch for your system, as listed in Microsoft Security Bulletin MS02-062. See References.
Microsoft originally provided a patch for this vulnerability in MS02-018, but it was superseded by the patch released with MS02-062, and then superseded by the patch released with MS03-018. See References.
Note: This vulnerability also affects several Cisco products that use IIS. For affected products and upgrade or patch information, refer to Cisco Security Advisory: Microsoft IIS Vulnerabilities in Cisco Products - MS02-018. See References.
References:
- CERT Advisory CA-2002-09: Multiple Vulnerabilities in Microsoft IIS.
- CIAC Information Bulletin M-066: Microsoft Cumulative Patch for Internet Information Services (IIS) Vulnerabilities.
- Cisco Systems Inc. Security Advisory, 2002 April 15 18:00 (UTC -0400): Microsoft IIS Vulnerabilities in Cisco Products - MS02-018.
- Internet Security Systems Security Alert #114: Multiple Remote Vulnerabilities in Microsoft IIS.
- Microsoft Knowledge Base Article 314339: MS02-018: Patch Available for Access Violation in URL Error Handling Vulnerability.
- Microsoft Knowledge Base Article 319733: MS02-018: April 2002 Cumulative Patch for Internet Information Services.
- Microsoft Security Bulletin MS02-018: Cumulative Patch for Internet Information Services (Q319733).
- Microsoft Security Bulletin MS02-062: Cumulative Patch for Internet Information Service (Q327696).
- Microsoft Security Bulletin MS03-018: Cumulative Patch for Internet Information Service (811114).
- National Infrastructure Protection Center Advisory 02-002: Multiple Remote Vulnerabilities in Microsoft's Internet Information Services (IIS).
- VulnWatch Mailing List, Thu Apr 11 2002 - 04:34:08 CDT: KPMG-2002009: Microsoft IIS W3SVC Denial of Service. (From Neohapsis archive)
- BID-4479: Microsoft IIS ISAPI Filter Access Violation Denial of Service Vulnerability
- CVE-2002-0072: The w3svc.dll ISAPI filter in Front Page Server Extensions and ASP.NET for Internet Information Server (IIS) 4.0, 5.0, and 5.1 does not properly handle the error condition when a long URL is provided, which allows remote attackers to cause a denial of service (crash) when the URL parser accesses a null pointer.
- OSVDB ID: 3326: Microsoft IIS URL Access Violation DoS
- US-CERT VU#521059: Microsoft Internet Information Server (IIS) vulnerable to DoS when URL request exceeds maximum allowed length
Platforms Affected:
- Microsoft Internet Information Server 4.0
- Microsoft Internet Information Server 5.0
- Microsoft Internet Information Server 5.1
Reported:
Apr 10, 2002
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