Check Point Advisories

Squid SNMP Parser ASN.1 Header Parsing Denial of Service (CVE-2004-0918)

Check Point Reference: CPAI-2004-194
Date Published: 28 Oct 2009
Severity: High
Last Updated: Wednesday 28 October, 2009
Source:
Industry Reference:CVE-2004-0918
Protection Provided by:

Security Gateway
R81, R80, R77, R75
Who is Vulnerable?
Vulnerability Description Squid is a full featured, open source web proxy caching server. It supports proxying FTP, HTTP, SSL, DNS and has support for Simple Network Management Protocol (SNMP). There is a vulnerability in the way Squid web proxy parses SNMP messages. An SNMP message with specially crafted ASN.1 length fields can generate memory access violation errors. The exception generated by these errors can cause the product to restart, creating a denial of service condition for active transactions. On Unix like systems when Squid is launched, two processes are spawned, a parent monitoring process and a child worker process. When the vulnerability is triggered, the worker process will terminate, causing all currently connected clients to be disconnected. After a couple seconds, the monitoring process will detect that the work process has failed and will start a new worker process. On Windows the Squid process is monitored by Service Control Manager. When the vulnerability is triggered, the Squid process will terminate, causing all currently connected clients to be disconnected. After a period of time (by default 60 seconds) Service Control Manager will restart the Squid process.

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

  1. In the IPS tab, click Protections and find the Squid SNMP Parser ASN.1 Header Parsing Denial of Service 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:  Proxy Server Enforcement Violation.
Attack Information:  Squid SNMP parser ASN.1 header parsing denial of service

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