Check Point Advisories

Multiple Vendor Telnet Client env_opt_add Buffer Overflow (CVE-2005-0468)

Vulnerability
Protection

Check Point Reference:	CPAI-2005-217
Date Published:	13 Oct 2009
Severity:	High
Last Updated:	Wednesday 14 May, 2014
Source:
Industry Reference:	CVE-2005-0468
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?
Vulnerability Description	The TELNET protocol is designed to provide a standard method of interfacing terminal devices and terminal-oriented processes to each other. It allows a computer to act as a remote terminal of another machine on a network. The TELNET protocol allows a user to connect to a remote host in order to control it. The remote host (which acts as a telnet server) accepts input directly from the user's computer (which acts as a telnet client). This protocol is detailed documented in RFC854. A vulnerability exists in the way the env_opt_add function of certain telnet clients processes the NEW-ENVIRON sub-options. A buffer in the vulnerable telnet client can be overflowed by a telnet server by sending a specially crafted SEND command. An attacker may exploit this flaw to execute arbitrary code on the target system with the privileges of the account executing the telnet client. In an attack scenario, where arbitrary code is attempted to be injected and executed on the target machine, the behaviour of the target is dependent on the intention of the malicious code. If such an attack is not executed successfully, the vulnerable application may terminate as a result of the attack attempt. If unexpected termination of the vulnerable application is the sole result of an attack, it has no impact on the overall operation of the attacked host. Furthermore, if the telnet session has been invoked by the attacker, the target user may not become aware that a failed attack attempt has transpired.

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 Multiple Vendor Telnet Client env_opt_add 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: Telnet Enforcement Violation.
Attack Information: Multiple Vendor Telnet Client env_opt_add buffer overflow