[squid-users] [ADVISORY] SQUID-2011:3 Buffer overflow in Gopher reply parser

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       Squid Proxy Cache Security Update Advisory SQUID-2011:3
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Advisory ID: SQUID-2011:3
Date: August 28, 2011
Summary: Buffer overflow in Gopher reply parser
Affected versions: Squid 3.0 -> 3.0.STABLE25
                         Squid 3.1 -> 3.1.14
                         Squid 3.2 -> 3.2.0.10
Fixed in Version: Squid 3.0.STABLE26, 3.1.15, 3.2.0.11
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      http://www.squid-cache.org/Advisories/SQUID-2005_1.txt
      http://www.squid-cache.org/Advisories/SQUID-2011_3.txt
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Problem Description:

  A bug exists in the code that parses responses from Gopher servers.
  The bug results in a buffer overflow if a Gopher server returns a
  line longer than 4096 bytes. The overflow results in memory
  corruption and usually crashes Squid.

  This is an extension of SQUID-2005:1 which has been opened in the
  Squid 3.x version code due to increased packet read sizes.

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Severity:

  A malicious user may set up a fake Gopher server and forward
  requests to it through Squid. Specially crafted responses from
  that server may cause Squid to restart.

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Updated Packages:

  This bug is fixed by Squid versions 3.2.0.11, 3.1.15, and
  3.0.STABLE26.

  In addition, patches addressing this problem can be found in our
  patch archives.

Squid-3.0:
  http://www.squid-cache.org/Versions/v3/3.0/changesets/squid-3.0-9193.patch

Squid-3.1:
 
http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10363.patch

Squid-3.2:
 
http://www.squid-cache.org/Versions/v3/3.2/changesets/squid-3.2-11294.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. This problem is
  limited to Squid-3.x versions with large read buffer sizes.

  Unpatched Squid-3.0 releases up to and including 3.0.STABLE25
  are vulnerable.

  Unpatched Squid-3.1 releases up to and including 3.1.14 are
  vulnerable.

  Unpatched Squid-3.2 releases up to and including 3.2.0.10 are
  vulnerable.

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Workarounds:

  Since real Gopher servers are extremely rare these days, there is
  almost no reason for Squid to contact a Gopher server. You can
  add a simple access control rule to deny all Gopher requests to
  Squid:

     acl Gopher proto Gopher
     http_access deny Gopher

  Restart or reconfigure Squid after editing squid.conf. Test your
  access controls with a simple request:

     % squidclient gopher://127.0.0.1/

  You should see an "Access Denied" message.

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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_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_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 found by Ben Hawkes, Google Security Team

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Revision history:

  2011-08-28 12:29 GMT Initial release of this document
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Received on Sun Aug 28 2011 - 16:58:25 MDT