[squid-announce] [ADVISORY] SQUID-2022:2 Buffer Over Read in SSPI and SMB Authentication

[Amos Jeffries]

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Squid Proxy Cache Security Update Advisory SQUID-2022:2
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Advisory ID:       | SQUID-2022:2
Date:              | September 23, 2022
Summary:           | Buffer Over Read
                    | in SSPI and SMB Authentication
Affected versions: | Squid 2.5.STABLE1 -> 2.7.STABLE9
                    | Squid 3.x -> 3.5.28
                    | Squid 4.x -> 4.17
                    | Squid 5.x -> 5.6
Fixed in version:  | Squid 5.7
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  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-41318>
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Problem Description:

  Due to an incorrect integer overflow protection Squid SSPI and
  SMB authentication helpers are vulnerable to a Buffer Overflow
  attack.

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Severity:

  This problem allows a remote client to perform a Denial of
  Service attack when Squid is configured to use NTLM or Negotiate
  authentication with one of the vulnerable helpers.

  This problem allows a remote client to extract sensitive
  information from machine memory when Squid is configured to use
  NTLM or Negotiate authentication with one of the vulnerable
  helpers. The scope of this information includes user credentials
  in decrypted forms, and also arbitrary memory areas beyond Squid
  and the helper itself.

  This attack is limited to authentication helpers built using the
  libntlmauth library shipped by Squid.

CVSS Score of 8.2
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:H/E:P/RL:O/RC:C/CR:H/IR:H/AR:H/MAV:X/MAC:X/MPR:X/MUI:X/MS:C/MC:X/MI:L/MA:H&version=3.1>
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Updated Packages:

This bug is fixed by Squid version 5.7.

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

Squid 4:
  <http://www.squid-cache.org/Versions/v4/changesets/SQUID-2022_2.patch>

Squid 5:
  <http://www.squid-cache.org/Versions/v5/changesets/SQUID-2022_2.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:

  Run this command to view the configured authentication helpers:

    (squid -k parse 2>&1) | grep "Processing: auth_param"

  Your Squid may be vulnerable if the result contains any of the following:
    ntlm_smb_lm_auth
    ntlm_sspi_auth
    ntlm_fake_auth
    negotiate_sspi_auth

  All Squid-2.5 up to and including 4.17 have vulnerable helpers.

  All Squid-5.x up to and including 5.6 have vulnerable helpers.

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Workaround:

Either,

  Disable use of the vulnerable authentication scheme.

Or,

  Replace the vulnerable helper with an alternative helper for the
  same authentication scheme.

Or,

  Replace the vulnerable helper binary with one built from an
  updated or patched Squid release. The remainder of Squid does not
  need updating to fix this.

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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
  <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.

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Credits:

  This vulnerability was discovered by LWIC.

  Fixed by Amos Jeffries of Treehouse Networks Ltd,
  based on patch by LWIC.

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Revision history:

  2019-03-17 14:24:42 UTC Initial Report
  2022-08-08 12:16:43 UTC Fix Released
  2022-09-23 05:00:00 UTC Advisory Released
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