Check Point Advisories

Exim SPA Authentication Buffer Overflow (CVE-2005-0022)

Vulnerability
Protection

Check Point Reference:	CPAI-2005-182
Date Published:	10 Nov 2009
Severity:	High
Last Updated:	Thursday 17 October, 2013
Source:
Industry Reference:	CVE-2005-0022
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?
Vulnerability Description	The Exim mail server is a full featured mail transfer agent (MTA). It offers the user several optional authentication mechanisms, one of which is Secure Password Authentication (SPA). Secure Password Authentication is also known as NTML authentication, which is commonly used by Windows-based software products. A vulnerability exists in the SPA authentication mechanism of Exim, a mail server. Due to insufficient input validation in the base64 decoding function, a stack buffer can be overflowed during the authentication process. An attacker can craft a special authentication request to execute arbitrary code on the remote system with the privileges of the user specified at compile time. In case an attack where code injection is not successful, the stack memory of the child process spawned to handle the attacker's request will be corrupted. In case an attack where code injection and execution is successful, the process flow of the process handling the request will be diverted. In such a case, the behavior of the target is dependent on the nature of the injected code.

Protection Overview

This protection will detect and block attempts to exploit this vulnerability

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

In the IPS tab, click Protections and find the Exim SPA Authentication Buffer Overflow protection using the Search tool and Edit the protection's settings.
Install policy on all Security Gateways.

This protection's log will contain the following information:

Attack Name: SMTP Protection Violation.
Attack Information: Exim SPA authentication buffer overflow