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ESB-2010.0799 - [Win][UNIX/Linux] Squid: Denial of service - Remote/unauthenticated

Date: 07 September 2010

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2010.0799
          Squid Proxy Cache Security Update Advisory SQUID-2010:3
                             7 September 2010

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Squid 3.0 through 3.0.STABLE25
                   Squid 3.1 through 3.1.7
                   Squid 3.2 through 3.2.0.1
Publisher:         Squid
Operating System:  Windows
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade

Original Bulletin: 
   http://www.squid-cache.org/Advisories/SQUID-2010_3.txt

- --------------------------BEGIN INCLUDED TEXT--------------------

__________________________________________________________________

    Squid Proxy Cache Security Update Advisory SQUID-2010:3
__________________________________________________________________

Advisory ID:            SQUID-2010:3
Date:                   September 03, 2010
Summary:                Denial of service in request processing
Affected versions:      Squid 3.0 -> 3.0.STABLE25
                        Squid 3.1 -> 3.1.7
                        Squid 3.2 -> 3.2.0.1
Fixed in version:       Squid 3.1.8, 3.2.0.2
__________________________________________________________________

     http://www.squid-cache.org/Advisories/SQUID-2010_3.txt
__________________________________________________________________

Problem Description:

 Due to an internal error in string handling Squid is vulnerable
 to a denial of service attack when processing specially crafted
 requests.

__________________________________________________________________

Severity:

 This problem allows any trusted client to perform a denial of
 service attack on the Squid service.

 There are applications already in general public use which can
 trigger this problem for 3.1 and 3.2 on occasion without intended
 malice.

__________________________________________________________________

Updated Packages:

 This bug is fixed by Squid versions 3.1.8 and 3.2.0.2

 In addition, patches addressing this problem for stable releases
 can be found in our patch archives:

Squid 3.0:
http://www.squid-cache.org/Versions/v3/3.0/changesets/squid-3.0-9189.patch

Squid 3.1:
http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10090.patch


 If you are using a prepackaged version of Squid then please refer
 to the package vendor for availability information on updated
 packages.

__________________________________________________________________

Determining if your version is vulnerable:

Squid-3.0:

 All Squid-3.0 versions up to and including 3.0.STABLE25 have
 some risk of being vulnerable to variations of the problem.
 The particular 0-day tests currently known do not trigger it.

Squid-3.1:

 All versions up to and including 3.1.7 are at some risk of being
 vulnerable to the problem and its variations.

 squid.conf containing with "ignore_expect_100 on" are vulnerable
 to the known active 0-day.

 Binaries built with --disable-http-violations are not vulnerable
 to the known active 0-day.

Squid-3.2:

 The 3.2.0.1 beta version is vulnerable under the same conditions
 as for Squid-3.1.

__________________________________________________________________

Workarounds:

 These workarounds apply only to the known active 0-day triggers.

 1) Checking that ignore_expect_100 squid.conf option is set to
    "off" (the default), or removed completely from squid.conf.

or,

 2) Building Squid with --disable-http-violations.

__________________________________________________________________

Contact details for the Squid project:

 For installation / upgrade support on binary packaged versions
 of Squid: Your first point of contact should be your binary
 package vendor.

 If you install and build Squid from the original Squid sources
 then the squid-users@squid-cache.org mailing list is your primary
 support point. For subscription details see
 http://www.squid-cache.org/Support/mailing-lists.html.

 For reporting of non-security bugs in the latest release
 the squid bugzilla database should be used
 http://www.squid-cache.org/bugs/.

 For reporting of security sensitive bugs send an email to the
 squid-bugs@squid-cache.org mailing list. It's a closed list
 (though anyone can post) and security related bug reports are
 treated in confidence until the impact has been established.

__________________________________________________________________

Credits:

 The vulnerability was discovered by Phil Oester.

__________________________________________________________________

Revision history:

 2010-08-30 14:19 GMT Initial Report
 2010-09-01 08:04 GMT Patches Released
 2010-09-03 09:00 GMT Initial version
__________________________________________________________________

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        http://www.auscert.org.au/render.html?cid=1980

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
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