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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

          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
Publisher:         Squid
Operating System:  Windows
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade

Original Bulletin:

- --------------------------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 ->
Fixed in version:       Squid 3.1.8,

Problem Description:

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



 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


Updated Packages:

 This bug is fixed by Squid versions 3.1.8 and

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

Squid 3.0:

Squid 3.1:

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


Determining if your version is vulnerable:


 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.


 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.


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



 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.


 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 mailing list is your primary
 support point. For subscription details see

 For reporting of non-security bugs in the latest release
 the squid bugzilla database should be used

 For reporting of security sensitive bugs send an email to the 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.



 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

- --------------------------END INCLUDED TEXT--------------------

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