[squid-users] [squid-announce] [ADVISORY] SQUID-2019:3 Denial of Service in HTTP Digest Authentication processing

[Amos Jeffries]

__________________________________________________________________

    Squid Proxy Cache Security Update Advisory SQUID-2019:3
__________________________________________________________________

Advisory ID:        SQUID-2019:3
Date:               July 12, 2019
Summary:            Denial of Service issue
                    in HTTP Digest Authentication processing.
Affected versions:  Squid 3.3.9 -> 3.5.28
                    Squid 4.x -> 4.7
Fixed in version:   Squid 4.8
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    http://www.squid-cache.org/Advisories/SQUID-2019_3.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-12525
__________________________________________________________________

Problem Description:

 Due to incorrect buffer management Squid is vulnerable to a
 denial of service attack when processing HTTP Digest
 Authentication credentials.

__________________________________________________________________

Severity:

 Due to incorrect input validation the HTTP Request header
 parser for Digest authentication may access memory outside the
 allocated memory buffer.

 On systems with memory access protections this can result in
 the Squid process being terminated unexpectedly. Resulting in a
 denial of service for all clients using the proxy.

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Updated Packages:

 This bug is fixed by Squid version 4.8.

 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-3.5-ec0d0f39cf28da14eead0ba5e777e95855bc2f67.patch>

Squid 4:
 <http://www.squid-cache.org/Versions/v4/changesets/squid-4-409956536647b3a05ee1e367424a24ae6b8f13fd.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-3.x up to and including 3.3.8 are not vulnerable.

 All Squid-3.3.9 up to and including 3.3.14 being used for Digest
 authentication are vulnerable.

 All Squid-3.4 versions up to and including 3.4.14 being used for
 Digest authentication are vulnerable.

 All Squid-3.5 versions up to and including 3.5.28 being used for
 Digest authentication are vulnerable.

 All Squid-4.x up to and including 4.7 being used for Digest
 Authentication are vulnerable.


To determine whether auth_param is configured for Digest
authentication use the command:

 squid -k parse | grep auth_param

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Workarounds:

Either;

 Remove 'auth_param digest ...' configuration settings from
 squid.conf.

Or,

 Build Squid with --disable-auth-digest


__________________________________________________________________

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.

__________________________________________________________________

Credits:

 This vulnerability was discovered by Jeriko One
 <jeriko.one at gmx.us>.

 Fixed by Amos Jeffries of Treehouse Networks Ltd.

__________________________________________________________________

Revision history:

 2019-05-14 14:56:49 UTC Initial Report
 2019-06-05 15:52:17 UTC CVE Assignment
 2019-06-08 21:09:23 UTC Patches Released
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END
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