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Squid Proxy Cache Security Update Advisory SQUID-2018:2
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Advisory ID: SQUID-2018:2
Date: Jan 19, 2018
Summary: Denial of Service issue
in HTTP Message processing.
Affected versions: Squid 3.x -> 3.5.27
Squid 4.x -> 4.0.22
Fixed in version: Squid 4.0.23
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http://www.squid-cache.org/Advisories/SQUID-2018_2.txt
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Problem Description:
Due to incorrect pointer handling Squid is vulnerable to denial
of service attack when processing ESI responses or downloading
intermediate CA certificates.
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Severity:
This problem allows a remote client delivering certain HTTP
requests in conjunction with certain trusted server responses 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 4.0.23.
In addition, patches addressing this problem for the stable
releases can be found in our patch archives:
Squid 3.5:
<http://www.squid-cache.org/Versions/v3/3.5/changesets/SQUID-2018_2.patch>
Squid 4:
<http://www.squid-cache.org/Versions/v4/changesets/SQUID-2018_2.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 configured with "log_uses_indirect_client off" are not
vulnerable.
All Squid-3.0 versions built with --enable-esi and being used for
reverse-proxy with squid.conf containing
"log_uses_indirect_client on" are vulnerable.
All Squid-3.1 and later versions up to and including
Squid-3.5.27 being used for reverse-proxy with squid.conf
containing "log_uses_indirect_client on" are vulnerable.
All Squid-4 up to and including Squid-4.0.22 being used for
reverse-proxy with squid.conf containing
"log_uses_indirect_client on" are vulnerable.
All unpatched Squid-4 up to and including Squid-4.0.22 being
used for TLS/HTTPS intercept proxy with squid.conf containing
"log_uses_indirect_client on" are vulnerable.
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Workarounds:
Configure "log_uses_indirect_client off" in squid.conf
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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@xxxxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxxxxxxxx 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 initial issue was reported by Louis Dion-Marcil on behalf of
GoSecure.
Fixed by Amos Jeffries from Treehouse Networks Ltd.
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Revision history:
2017-12-13 20:09:30 UTC Initial Report
2018-01-18 23:10:00 UTC Patches Released
2018-01-21 07:45:00 UTC Advisory and fixed packages released
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END
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