Vulnerability Note VU#886006

Squid vulnerable to buffer overflow via an overly long WCCP message

Overview

The Squid web proxy cache is vulnerable to a buffer overflow when handing overly long web cache communications protocol (WCCP) messages. Such messages could crash the Squid process and produce a denial of service condition.

I. Description

Squid functions as a web proxy and cache application for number of protocols. It supports WCCP to enable communications between routers and web caches. A recvfrom() call in the WCCP handling routines accepts more data than the buffer size may be able to handle. An attacker may be able to crash the Squid process by sending an overly-long WCCP message.

II. Impact

A remote unauthenticated attacker may be able to crash the Squid process and create a denial of service condition. Sites not using WCCP, which is disabled by default, are not affected.

III. Solution

Apply an update

Administrators should obtain an updated version of Squid from their vendor if WCCP is used.

Team Squid has created a patch for the current release version of Squid, described in Squid Proxy Cache Security Update Advisory SQUID-2005:3.

This flaw has been patched in Squid 2.5.STABLE8-RC4. More details are available in the Squid Bugzilla bug #1217.

Sites not requiring WCCP should disable the 'wccp_router' option in the Squid configuration file. Note that this option is disabled by default.

Systems Affected

Vendor	Status	Date Notified	Date Updated
Squid	Vulnerable	4-Feb-2005

References

http://www.squid-cache.org/Advisories/SQUID-2005_3.txt
http://www.squid-cache.org/bugs/show_bug.cgi?id=1217
http://secunia.com/advisories/14076/

Credit

Thanks to Team Squid for reporting this vulnerability, who in turn credit the FSC Vulnerability Research Team with the discovery of this flaw.

This document was written by Ken MacInnis based primarily on information provided by Team Squid.

Other Information

Date Public:	2005-01-28
Date First Published:	2005-02-04
Date Last Updated:	2005-02-08
CERT Advisory:
CVE-ID(s):	CAN-2005-0211
NVD-ID(s):	CAN-2005-0211
US-CERT Technical Alerts:
Metric:	7.50
Document Revision:	20

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