2000601 : Microsoft IIS can be remotely crashed by excessively long client requests

Medium RiskMedium Risk

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Event description Jump to the top of this document

Microsoft Internet Information Server (IIS) is vulnerable to a denial of service attack. An attacker can send a very large client request, such as a header and CGI request that contains between 4 KB and 8 KB of data to crash the server. This attack can be embedded in many different requests.

Products that have this security check Jump to the top of this document

HTTP_URL_Name_Very_Long

This signature detects unusually long URL authority or path names in a URL. The path name is all data that is located before a query (?) character.

False Positive:A false positive is possible if a valid URL is requested, which is longer than the configured maximum. An abundance of unprintable characters is indicative of a buffer overflow attack; if the characters are primarily ASCII, then this event is most likely a false positive.

Affected platforms Jump to the top of this document

How to remove this vulnerability Jump to the top of this document

Apply the latest Windows NT 4.0 Service Pack (SP4 or later), available from the Windows NT Service Packs Web page. See References.

— OR —

As an alternative, Windows NT SP3 users can apply the post-SP3 iis-fix patch, as listed in Microsoft Knowledge Base Article Q143484. See References.

References Jump to the top of this document

Microsoft Product Support Services
Windows NT Service Packs
http://www.microsoft.com/ntserver/downloads

Microsoft Knowledge Base Article 143484
IIS Services Stop with Large Client Requests
http://support.microsoft.com/default.aspx?scid=kb;[LN];143484

Common Vulnerabilities and Exposures
Denial of service in IIS using long URLs.
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-1999-0281

BugTraq
Microsoft IIS Long URL Denial of Service Vulnerability
http://www.securityfocus.com/bid/2654

Information about this document Jump to the top of this document

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This page was created on Thu Jun 11 09:06:03 2009