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AUSCERT External Security Bulletin Redistribution
ESB-2018.0227
Squid Proxy Cache Security Update Advisories SQUID-2018:1 and SQUID-2018:2
23 January 2018
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Squid
Publisher: Squid
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Impact/Access: Denial of Service -- Remote with User Interaction
Resolution: Patch/Upgrade
Original Bulletin:
http://www.squid-cache.org/Advisories/SQUID-2018_1.txt
http://www.squid-cache.org/Advisories/SQUID-2018_2.txt
Comment: This bulletin contains two (2) Squid security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
__________________________________________________________________
Squid Proxy Cache Security Update Advisory SQUID-2018:1
__________________________________________________________________
Advisory ID: SQUID-2018:1
Date: Jan 19, 2018
Summary: Denial of Service issue
in ESI Response processing.
Affected versions: Squid 3.x -> 3.5.27
Squid 4.x -> 4.0.22
Fixed in version: Squid 4.0.23
__________________________________________________________________
http://www.squid-cache.org/Advisories/SQUID-2018_1.txt
__________________________________________________________________
Problem Description:
Due to incorrect pointer handling Squid is vulnerable to denial
of service attack when processing ESI responses.
__________________________________________________________________
Severity:
This problem allows a remote server delivering certain ESI
response syntax to trigger a denial of service for all clients
accessing the Squid service.
This problem is limited to the Squid custom ESI parser.
Squid built to use libxml2 or libexpat XML parsers do not have
this problem.
__________________________________________________________________
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_1.patch>
Squid 4:
<http://www.squid-cache.org/Versions/v4/changesets/SQUID-2018_1.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:
All Squid-2.x are not vulnerable.
All Squid built with --disable-esi are not vulnerable.
All Squid configured with "esi_parser expat" are not vulnerable.
All Squid configured with "esi_parser libxml2" are not
vulnerable.
All Squid-3.0 versions built without --enable-esi are not
vulnerable.
All Squid-3.0 versions built with --enable-esi and using
custom ESI parser for reverse-proxy are vulnerable.
All Squid-3.1 and later versions up to and including
Squid-3.5.27 being used for reverse-proxy are vulnerable.
All Squid-3.1 and later versions up to and including
Squid-3.5.27 being used for TLS / HTTPS interception are
vulnerable.
All unpatched Squid-4 up to and including Squid-4.0.22 being
used as reverse-proxy are vulnerable.
All unpatched Squid-4 up to and including Squid-4.0.22 being
used as TLS/HTTPS intercept proxy are vulnerable.
__________________________________________________________________
Workarounds:
Either;
Build Squid with --disable-esi
Or,
Build Squid with "--enable-esi --with-libxml2" and in squid.conf
configure "esi_parser libxml2"
Or,
Build Squid with "--enable-esi --with-expat" and in squid.conf
configure "esi_parser expat"
__________________________________________________________________
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.
__________________________________________________________________
Credits:
The initial issue was reported by Louis Dion-Marcil on behalf of
GoSecure.
Fixed by Amos Jeffries from Treehouse Networks Ltd.
__________________________________________________________________
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
__________________________________________________________________
END
__________________________________________________________________
Squid Proxy Cache Security Update Advisory SQUID-2018:2
__________________________________________________________________
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
__________________________________________________________________
http://www.squid-cache.org/Advisories/SQUID-2018_2.txt
__________________________________________________________________
Problem Description:
Due to incorrect pointer handling Squid is vulnerable to denial
of service attack when processing ESI responses or downloading
intermediate CA certificates.
__________________________________________________________________
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.
__________________________________________________________________
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.
__________________________________________________________________
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.
__________________________________________________________________
Workarounds:
Configure "log_uses_indirect_client off" in squid.conf
__________________________________________________________________
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.
__________________________________________________________________
Credits:
The initial issue was reported by Louis Dion-Marcil on behalf of
GoSecure.
Fixed by Amos Jeffries from Treehouse Networks Ltd.
__________________________________________________________________
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
__________________________________________________________________
END
- --------------------------END INCLUDED TEXT--------------------
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===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072
Internet Email: auscert@auscert.org.au
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