Check Point Advisories

Microsoft Internet Authentication Service MS-CHAP Security Bypass (MS09-071; CVE-2009-3677)

Check Point Reference: CPAI-2009-253
Date Published: 8 Dec 2009
Severity: High
Last Updated: Sunday 07 February, 2016
Source:
Industry Reference:CVE-2009-3677
Protection Provided by:

Security Gateway
R81, R80, R77, R75, R71, R70, R65
Who is Vulnerable?
Vulnerability Description An elevation of privilege vulnerability has been reported in the Internet Authentication Service. Internet Authentication Service (IAS) is the Microsoft implementation of a Remote Authentication Dial-in User Service (RADIUS) server and proxy. As a RADIUS server, IAS performs centralized connection authentication, authorization, and accounting for many types of network access. A remote attacker may exploit this issue to gain access to network resources under the privileges of a specific authorized user. The vulnerability is due to an error in the Internet Authentication Service that fails to correctly validate MS-CHAP v2 authentication requests. This causes the server to consider the authentication request as valid, even when incorrect credentials may have been provided. A remote attacker might trigger this issue by sending an incorrectly formed MS-CHAP v2 authentication request to the Internet Authentication Service, causing the attacker to obtain access to network resources under the privileges of a specific authorized user.

Protection Overview

This protection detects and blocks malformed MS-CHAP v2 authentication requests to the vulnerable service.

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 Internet Authentication Service MS-CHAP Security Bypass (MS09-071) 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:  Authentication Protocols Violation.
Attack Information:  Microsoft Internet Authentication Service MS-CHAP security bypass (MS09-071)

×
  Feedback
This website uses cookies for its functionality and for analytics and marketing purposes. By continuing to use this website, you agree to the use of cookies. For more information, please read our Cookies Notice.
OK