Low Risk Vulnerability in Active Directory

Peter Winter-Smith of NGSSoftware has discovered a low risk vulnerability in
Active Directory which can allow an unauthenticated user to cause a denial
of service condition on any affected system.

The only affected platform is Windows 2000 with Active Directory. Windows
2003 Server is NOT affected by this issue.

The vulnerability occurs when Active Directory attempts to parse an LDAP
request containing the ASN.1 type 0x08. As soon as this type is encountered,
the hosting system reaches a 100% CPU usage condition from which it does not
seem to recover. Making multiple such requests will render the system
completely unresponsive.

This issue has been fixed in the Microsoft bulletin MS07-039, which can be
found at:

http://www.microsoft.com/technet/security/Bulletin/MS07-039.mspx

NGSSoftware Insight Security Research
http://www.ngssoftware.com/
http://www.databasesecurity.com/
http://www.nextgenss.com/
+44(0)208 401 0070

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