Vulnerability Note VU#924198

Squid LDAP authentication routines fail to check for invalid input

Overview

The Squid LDAP authentication routine squid_ldap_auth() fails to check for input characters, such as whitespace, that could be misused to possibly bypass access restrictions.

I. Description

Squid functions as a web proxy and cache application for a number of protocols, and includes support for lightweight directory access protocol (LDAP) authentication. However, the squid_ldap_auth() function does not properly check for and sanitize input containing whitespace. This may allow remote attackers to log in using variants of existing user names, leading to bypass of security restrictions or creation of arbitrary accounting data.

II. Impact

Remote attackers may be able to gain elevated privileges or could pollute accounting data with invalid entries. This flaw is platform independent.

III. Solution

Apply an update

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

Team Squid has created a patch for the current release version of Squid: squid-2.5.STABLE7-ldap_spaces.patch

This flaw has been patched in Squid 2.5.STABLE8-RC4. More details are available in the Squid Bugzilla bug #1187.

Squid administrators may either disable LDAP authentication or block usernames containing whitespace as a workaround.

Systems Affected

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

References

http://www.squid-cache.org/Versions/v2/2.5/bugs/#squid-2.5.STABLE7-ldap_spaces
http://www.squid-cache.org/bugs/show_bug.cgi?id=1187
http://secunia.com/advisories/13843/

Credit

Thanks to Team Squid for reporting this vulnerability, who in turn credit Andrew P 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:	2005-01-17
Date First Published:	2005-02-04
Date Last Updated:	2005-02-11
CERT Advisory:
CVE-ID(s):	CAN-2005-0173
NVD-ID(s):	CAN-2005-0173
US-CERT Technical Alerts:
Metric:	6.30
Document Revision:	24

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