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    Squid Proxy Cache Security Update Advisory SQUID-2016:3
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Advisory ID:        SQUID-2016:3
Date:               April 02, 2016
Summary:            Buffer overrun issue
                    in pinger ICMPv6 processing.
Affected versions:  Squid 3.1.0 -> 3.5.15
                    Squid 4.0 -> 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_3.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-3947
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Problem Description:

 Due to a buffer overrun Squid pinger binary is vulnerable to
 denial of service or information leak attack when processing
 ICMPv6 packets.

 This bug also permits the server response to manipulate other
 ICMP and ICMPv6 queries processing to cause information leak.
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Severity:

 This bug allows any remote server to perform a denial of service
 attack on the Squid service by crashing the pinger. This may
 affect Squid HTTP routing decisions. In some configurations,
 sub-optimal routing decisions may result in serious service
 degradation or even transaction failures.

 If the system does not contain buffer-overrun protection leading
 to that crash this bug will instead allow attackers to leak
 arbitrary amounts of information from the heap into Squid log
 files. This is of higher importance than usual because the pinger
 process operates with root priviliges.
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Updated Packages:

 This bug is fixed by Squid version 3.5.15 and 4.0.8.

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

Squid 3.1:
 http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10495.patch

Squid 3.2:
 http://www.squid-cache.org/Versions/v3/3.2/changesets/squid-3.2-11839.patch

Squid 3.3:
 http://www.squid-cache.org/Versions/v3/3.3/changesets/squid-3.3-12694.patch

Squid 3.4:
 http://www.squid-cache.org/Versions/v3/3.4/changesets/squid-3.4-13232.patch

Squid 3.5:
 http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14015.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 Squid-2.x versions are not vulnerable to this problem.

 All Squid-3.0 versions are not vulnerable to this problem.

 All Squid built with --disable-icmp are not vulnerable to this
 problem.

 All Squid built with --disable-ipv6 are not vulnerable to this
 problem.

 All Squid-3.x configured with "pinger_enable off" in squid.conf
 are not vulnerable to this problem.

 Check the server running processes list to determine if the Squid
 service is running a "pinger" child process.

 All unpatched Squid-3 versions up to and including 3.5.15
 running the pinger process are vulnerable to this problem.

 All unpatched Squid-4 versions up to and including 4.0.7
 running the pinger process are vulnerable to this problem.

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Workaround:

 Disable the pinger process in squid.conf:

   pinger_enable off

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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@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@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:

 The vulnerability was reported and fixed by Yuriy M. Kaminskiy.

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Revision history:

 2016-02-21 23:42:28 GMT Initial Report
 2016-03-28 22:52:58 GMT Patch Released
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