Squid: Remote DoS vulnerability

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200410-15 / squid
Release Date	October 18, 2004
Latest Revision	December 30, 2007: 03
Impact	normal
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-proxy/squid	< 2.5.7	>= 2.5.7	All supported architectures

Related bugreports: #67167

Synopsis

Squid contains a vulnerability in the SNMP module which may lead to a denial of service.

2. Impact Information

Background

Squid is a full-featured Web proxy cache designed to run on Unix systems. It supports proxying and caching of HTTP, FTP, and other URLs, as well as SSL support, cache hierarchies, transparent caching, access control lists and many other features.

Description

A parsing error exists in the SNMP module of Squid where a specially-crafted UDP packet can potentially cause the server to restart, closing all current connections. This vulnerability only exists in versions of Squid compiled with the 'snmp' USE flag.

Impact

An attacker can repeatedly send these malicious UDP packets to the Squid server, leading to a denial of service.

3. Resolution Information

Workaround

Disable SNMP support or filter the port that has SNMP processing (default is 3401) to allow only SNMP data from trusted hosts.

To disable SNMP support put the entry snmp_port 0 in the squid.conf configuration file.

To allow only the local interface to process SNMP, add the entry "snmp_incoming_address 127.0.0.1" in the squid.conf configuration file.

Resolution

All Squid users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge sync

# emerge -pv ">=net-proxy/squid-2.5.7"
# emerge ">=net-proxy/squid-2.5.7"

4. References

Page updated October 18, 2004

Summary: This is a Gentoo Linux Security Advisory

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