SecurityvulnsSECURITYVULNS:DOC:56Security Bulletin (MS00-023)
Microsoft Security Bulletin (MS00-023)
Patch Available for "Myriad Escaped Characters" Vulnerability
Originally Posted: April 12, 2000
Summary
Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Internet Information Server. The
vulnerability could allow a malicious user to slow a web server's
response or prevent it from providing service altogether for a period
of time.
Frequently asked questions regarding this vulnerability and the
patch can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-023.asp
Issue
Special characters can be embedded in URLs by use of so-called escaped
character sequences. By providing a specially-malformed URL with an
extremely large number of escaped characters, a malicious user could
arbitrarily increase the work factor associated with parsing the
escaped characters, thereby consuming much or all of the CPU
availability on the server and preventing useful work from being
done.
The vulnerability does not provide any capability to cause the server
to fail, or to add, change or delete data on it. The slowdown would
only last until the URL had been processed, at which point service
would return to normal.
Affected Software Versions
- Microsoft Internet Information Server 4.0
- Microsoft Internet Information Server 5.0
Patch Availability
- Internet Information Server 4.0
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20292 - Internet Information Server 5.0
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20286
Note: Additional security patches are available at the Microsoft
Download Center
More Information
Please see the following references for more information related to
this issue.
- Frequently Asked Questions: Microsoft Security Bulletin MS00-023,
http://www.microsoft.com/technet/security/bulletin/fq00-023.asp - Microsoft Knowledge Base article Q254142 discusses this issue and
will be available soon. - Microsoft TechNet Security web site,
http://www.microsoft.com/technet/security/default.asp
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft
Technical Support is available at
http://support.microsoft.com/support/contact/default.asp.
Acknowledgments
Microsoft thanks Vanja Hrustic of the Relay Group for reporting the
"Myriad Escaped Character" vulnerability to us and working with us to
protect customers.
Revisions
- April 12, 2000: Bulletin Created.
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Last updated April 12, 2000
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