Check Point Advisories

Microsoft Active Directory SPN Validation Denial of Service (MS11-005; CVE-2011-0040)

Check Point Reference: CPAI-2011-012
Date Published: 8 Feb 2011
Severity: High
Last Updated: Sunday 18 January, 2015
Source:
Industry Reference:CVE-2011-0040
Protection Provided by:

Security Gateway
R81, R80, R77, R75, R71, R70, R65
Who is Vulnerable?
Vulnerability Description A denial of service vulnerability has been reported in implementations of Microsoft Windows Active Directory due to improper validation of service principal names (SPN), which could result in SPN collisions The vulnerability is due to an error in Active Directory that fails to properly process specially crafted requests to update the service principal name (SPN) and can result in name collisions in the domain. A remote attacker could exploit this vulnerability by sending specially crafted packets to the Active Directory server. The attacker must have valid local administrator privileges on the domain-joined computer in order to exploit this vulnerability. An attacker who successfully exploited this vulnerability could cause name collisions in the domain, causing the authentication of the services that use the SPN to be downgraded to NTLM, and may cause the service to become unavailable.

Protection Overview

This protection will detect and block attempts to exploit this vulnerability via specially crafted SPN requests.

In order for the protection to be activated, update your Security Gateway product to the latest IPS update. For information on how to update IPS, go to SBP-2006-05, click on Protection tab and select the version of your choice.

Security Gateway R80 / R77 / R75 / R71 / R70 / R65

  1. In the IPS tab, click Protections and find the Microsoft Active Directory SPN Validation Denial of Service (MS11-005) protection using the Search tool and Edit the protection's settings.
  2. Install policy on all Security Gateways.

This protection's log will contain the following information:

Attack Name:  MS-RPC over CIFS Enforcement Violation.
Attack Information:  Microsoft Active Directory SPN validation denial of service (MS11-005)

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