[squid-users] Advisory SQUID-2010:1 - Denial of Service issue in DNS handling

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       Squid Proxy Cache Security Update Advisory SQUID-2010:1
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Advisory ID: SQUID-2010:1
Date: January 28, 2010
Summary: Denial of Service issue in DNS handling
Affected versions: Squid 2.x,
                         Squid 3.0 -> 3.0.STABLE21,
                         Squid 3.1 -> 3.1.0.15
Fixed in version: Squid 3.0.STABLE22, 3.1.0.16
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      http://www.squid-cache.org/Advisories/SQUID-2010_1.txt
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Problem Description:

  Due to incorrect data validation Squid is vulnerable to a denial
  of service attack when processing specially crafted DNS packets.

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Severity:

  This problem allows any trusted client or external server who can
  determine the squid receiving port to perform a short-term denial
  of service attack on the Squid service.

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Updated Packages:

  This bug is fixed by Squid versions 3.0.STABLE22 and 3.1.0.16

  In addition, patches addressing these problems can be found In
  our patch archives:

Squid 2.x:
  http://www.squid-cache.org/Versions/v2/HEAD/changesets/12597.patch

Squid 3.0:
  http://www.squid-cache.org/Versions/v3/3.0/changesets/squid-3.0-9151.patch

Squid 3.1:
  http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-9853.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:

  Squid still using the obsolete dnsserver are not vulnerable.

  The ignore_unknown_nameservers option affects the severity of
  this vulnerability. When set to "on" (the default) risk is low.
  When set to "off" the vulnerability risk is increased.

  All unpatched Squid-3.0 versions up to and including 3.0.STABLE21
  are vulnerable.

  All unpatched Squid-3.1 versions up to and including 3.1.0.15 are
  vulnerable.

  All unpatched Squid-2.x versions are vulnerable.

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Workarounds:

  Using all of the following steps are required to protect a
  vulnerable Squid from this and other forms of DNS attack.

  * Ensuring the ignore_unknown_nameservers is turned on.

  * Ensuring that DNS packets cannot be sent to Squid from
    untrusted nameservers or other machines.

  The most secure implementation of these requirements is to use
  a nameserver running on the localhost IP dedicated for secure use
  by Squid and any other services on the Squid machine.
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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://www.squid-cache.org/bugs/>.

  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:

  Zero-Day attributed to work by Fabian Yamaguchi.

  The vulnerability was reported by Tomas Hoger of RedHat.

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Revision history:

  2010-01-14 18:05 GMT Initial Report
  2010-01-16 03:51 GMT Patches released.
  2010-02-01 04:49 GMT Squid-3 bundled fixes and advisory released.
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Received on Mon Feb 01 2010 - 10:09:52 MST