Squid: Denial of service when using NTLM authentication — GLSA 200409-04

Squid is vulnerable to a denial of service attack which could crash its NTLM helpers.

Affected Packages

net-proxy/squid on all architectures
Affected versions <= 2.5.6-r1
Unaffected versions >= 2.5.6-r2, < 2.5

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

Squid 2.5.x versions contain a bug in the functions ntlm_fetch_string() and ntlm_get_string() which lack checking the int32_t offset "o" for negative values.

Impact

A remote attacker could cause a denial of service situation by sending certain malformed NTLMSSP packets if NTLM authentication is enabled.

Workaround

Disable NTLM authentication by removing any "auth_param ntlm program ..." directives from squid.conf or use ntlm_auth from Samba-3.x.

Resolution

All Squid users should upgrade to the latest stable version:

 # emerge sync
 
 # emerge -pv ">=net-www/squid-2.5.6-r2"
 # emerge ">=net-www/squid-2.5.6-r2"

References

Release Date
September 02, 2004

Latest Revision
December 30, 2007: 03

Severity
normal

Exploitable
remote

Bugzilla entries