Software Engineering Institute

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.

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.

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.