[squid-announce] [ADVISORY] SQUID-2023:1 Request/Response smuggling in HTTP(S) and ICAP

[Amos Jeffries]

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Squid Proxy Cache Security Update Advisory SQUID-2023:1
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Advisory ID:       | SQUID-2023:1
Date:              | October 22, 2023
Summary:           | Request/Response smuggling in HTTP(S) and ICAP
Affected versions: | Squid 2.6.STABLE10  -> 2.7.STABLE9
                    | Squid 3.x -> 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 chunked decoder lenience Squid is vulnerable to
  Request/Response smuggling attacks when parsing HTTP/1.1
  and ICAP messages.

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Severity:

  This problem allows a remote attacker to perform
  Request/Response smuggling past firewall and frontend security
  systems when the upstream server interprets the chunked encoding
  syntax differently from Squid.

  This attack is limited to the HTTP/1.1 and ICAP protocols which
  support receiving Transfer-Encoding:chunked.

CVSS Score of 9.3
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N&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_1.patch>

Squid 6:
  <http://www.squid-cache.org/Versions/v6/SQUID-2023_1.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 5.1 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:

  * ICAP issues can be reduced by ensuring only trusted ICAP
    services are used, with TLS encrypted connections
    (ICAPS extension).

  *  There is no workaround for the HTTP Request Smuggling issue.

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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 Keran Mu and Jianjun Chen,
  from Tsinghua University and Zhongguancun Laboratory.

  Fixed by Amos Jeffries of Treehouse Networks Ltd.

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Revision history:

  2023-09-01 04:34:00 UTC Initial Report
  2023-10-01 08:43:00 UTC Patch Available
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