Vulnerability Note VU#487905

Microsoft Windows Active Directory fails to properly validate LDAP requests

Overview

A vulnerability in Windows Active Directory could allow a remote attacker to execute arbitrary code on a vulnerable system.

I. Description

The Lightweight Directory Access Protocol (LDAP) is a standard protocol that enables users to query or modify the data in a meta directory. Microsoft's Active Directory is a directory service provided with Windows 2000 Server and Windows 2003 Server that stores information about objects on a network and makes this information available to users and network administrators. LDAP is the primary access protocol for Windows Active Directory.

The LDAP service provided with these systems fails to perform sufficient checks for the number of convertible attributes included in a LDAP request. This vulnerability could be exploited by a remote attacker with the ability to supply a specially crafted packet to the affected system. Microsoft states that the attacker would not need to be authenticated to exploit this vulnerability on an affected Windows 2000 Server system while the attacker must have valid authentication credentials to exploit this vulnerability on an affected Windows Server 2003 system.

II. Impact

A remote attacker may be to execute arbitrary code on an affected system or cause the Active Directory service to crash, resulting in a denial of service.

III. Solution

Apply a patch from the vendor

Microsoft has addressed this issue in Microsoft Security Bulletin MS07-039. Users are encouraged to review this bulletin and apply the updates it refers to.
Workarounds
In addition to the patches referred to above, Microsoft Security Bulletin MS07-039 also contains several workarounds for this issue. Users, particularly those who are unable to apply the patches are encouraged to implement these workarounds.

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	10-Jul-2007

References

http://www.microsoft.com/technet/security/bulletin/ms07-039.mspx
http://secunia.com/advisories/26002/
http://www.iss.net/threats/267.html

Credit

Thanks to Microsoft for reporting this vulnerability. Microsoft, in turn, credits Neel Mehta of IBM Internet Security Systems X-Force, for reporting this issue to them.

This document was written by Chad R Dougherty.

Other Information

Date Public	07/10/2007
Date First Published	07/10/2007 03:51:54 PM
Date Last Updated	07/19/2007
CERT Advisory
CVE Name	CVE-2007-0040
Metric	12.66
Document Revision	8