[squid-announce] [ADVISORY] SQUID-2023:3 Denial of Service in HTTP Digest Authentication

[Amos Jeffries]

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   Squid Proxy Cache Security Update Advisory SQUID-2023:3
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Advisory ID:       | SQUID-2023:3
Date:              | October 22, 2023
Summary:           | Denial of Service in HTTP Digest Authentication
Affected versions: | Squid 3.2 -> 3.5.28
                    | Squid 4.x -> 4.16
                    | Squid 5.x -> 5.9
                    | Squid 6.x -> 6.3
Fixed in version:  | Squid 6.4
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Problem Description:

  Due to a buffer overflow bug Squid is vulnerable to a Denial of
  Service attack against HTTP Digest Authentication

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Severity:

  This problem allows a remote client to perform buffer overflow
  attack writing up to 2 MB of arbitrary data to heap memory
  when Squid is configured to accept HTTP Digest Authentication.

  On machines with advanced memory protections this will result
  in a Denial of Service against all users of the Squid proxy.

CVSS Score of 9.9
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H&version=3.1>

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Updated Packages:

This bug is fixed by Squid version 6.4.

  In addition, patches addressing this problem for the stable
  releases can be found in our patch archives:

Squid 5:
  <http://www.squid-cache.org/Versions/v5/SQUID-2023_3.patch>

Squid 6:
  <http://www.squid-cache.org/Versions/v6/SQUID-2023_3.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 older than 5.0.5 have not been tested and should be assumed
  to be vulnerable.

  All Squid-5.x up to and including 5.9 are vulnerable.

  All Squid-6.x up to and including 6.3 are vulnerable.

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Workaround:

   Disable HTTP Digest authentication until Squid can be
   upgraded or patched.

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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 you 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
  <https://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.

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Credits:

  This vulnerability was discovered by Joshua Rogers of Opera
  Software.

  Fixed by Alex Bason.

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Revision history:

  2021-03-22 00:59:20 UTC Initial Report
  2023-10-13 17:31:11 UTC Patch Published
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