[squid-announce] [ADVISORY] SQUID-2016:4 Denial of Service issue in HTTP Response processing.

[Amos Jeffries]

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Squid Proxy Cache Security Update Advisory SQUID-2016:4
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Advisory ID:        SQUID-2016:4
Date:               April 02, 2016
Summary:            Denial of Service issue
                    in HTTP Response processing.
Affected versions:  Squid 3.x -> 3.5.15
                    Squid 4.x -> 4.0.7
Fixed in version:   Squid 4.0.8, 3.5.16
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    http://www.squid-cache.org/Advisories/SQUID-2016_4.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-3948
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Problem Description:

 Due to incorrect bounds checking Squid is vulnerable to a denial
 of service attack when processing HTTP responses.

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Severity:

 This problem allows a malicious client script and remote server
 delivering certain unusual HTTP response syntax to trigger a
 denial of service for all clients accessing the Squid service.

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Updated Packages:

 This bug is fixed by Squid version 3.5.16 and 4.0.8.

 In addition, a patch addressing this problem for the stable
 release can be found in our patch archives:

Squid 3.5:
 http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14016.patch

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

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Determining if your version is vulnerable:

 All unpatched Squid-3.0 versions are vulnerable.

 All unpatched Squid-3.1 versions are vulnerable.

 All unpatched Squid-3.2 versions are vulnerable.

 All unpatched Squid-3.3 versions are vulnerable.

 All unpatched Squid-3.4 versions are vulnerable.

 All unpatched Squid-3.5 up to and including Squid-3.5.15 are
 vulnerable.

 All unpatched Squid-4.0 up to and including 4.0.7 are vulnerable.

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Workaround:

 There are no good workarounds known for this vulnerability.

 The following squid.conf settings can protect Squid-3.5 (only):

   acl Vary rep_header Vary .
   store_miss deny Vary

Or,

 The following squid.conf setting can protect Squid-3.0 or later:

   cache deny all

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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 your install and build Squid from the original Squid sources
 then the squid-users at lists.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 STABLE release
 the squid bugzilla database should be used
 <http://bugs.squid-cache.org/>.

 For reporting of security sensitive bugs send an email to the
 squid-bugs at lists.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.

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Credits:

 This vulnerability was reported by Santiago R. Rincon of Debian.
 Fixed by Amos Jeffries from Treehouse Networks Ltd.

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Revision history:

 2016-03-20 11:25:04 UTC Initial Report
 2016-04-01 06:15:31 UTC Patch Released
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END