[squid-users] [ADVISORY] SQUID-2011:2 Password truncation in NCSA using DES

From: Amos Jeffries <squid3_at_treenet.co.nz>
Date: Sun, 28 Aug 2011 22:29:18 +1200


       Squid Proxy Cache Security Update Advisory SQUID-2011:2

Advisory ID: SQUID-2011:2
Date: August 27, 2010
Summary: Password truncation in NCSA using DES
Affected versions: Squid 3.0 -> 3.0.STABLE25
                         Squid 3.1 -> 3.1.14
                         Squid 3.2 ->
Fixed in version: Squid, 3.1.15, 3.0.STABLE26


Problem Description:

  DES algorithm implemented by htpasswd and crypt() in some popular
  encryption libraries silently truncates passwords. Squid NCSA
  authentication helper permits long and complex passwords to be
  used with DES despite this well known issue. Leaving users with
  a false view of their security.



  This problem hides potential security issues and allows attackers
  to bypass security controls relying on long and hard to guess


Updated Packages:

  This bug is fixed by Squid version

  Squid version 3.1.15 and 3.0.STABLE26 contain a partial fix.
  To allow a period of transition for administrators of large
  networks this release contains a helper which ALERTS in cache.log
  but does not block user logins.

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

Squid 3.0: (transitional protection)

Squid 3.1: (transitional protection)

Squid 3.2: (full protection)

  If you are using a prepackaged version of Squid then please refer
  to the package vendor for availability information on updated


Determining if your version is vulnerable:

  Squid and its cache are not harmed by this vulnerability. The
  issue is limited to the NCSA helper and potential third-party
  access to protected resources.

  ncsa_auth or basic_ncsa_auth helpers bundled with Squid releases
  up to are vulnerable.

  The helpers bundled with 3.1.15 and 3.0.STABLE26 will warn
  loudly when this vulnerability is encountered by any user, but
  will allow login to proceed.

Manual vulnerability test of the helper:

  * create a user account with 9-character password:

      # htpasswd -b /test test 123456789

  * run the helper and enter the test credentials,
    both truncated to 8 characters and in full:

      # ncsa_auth /test
      test 12345678
      test 123456789

  If the helper produces "OK" to both of these it is vulnerable.

  If the helper produces "ERR" to either one it is not vulnerable.

  The htpasswd -m option affects the vulnerability. When -m is used
  long passwords are stored in a more secure MD5 hash which is not



  Use the -m option on htpasswd when encrypting credentials.

  Ensuring that MD5 encryption is used by all tools updating the
  credentials file.

  The most secure implementation of these requirements is to use
  salted MD5 with magic strings to encrypt the passwords.

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

  For reporting of non-security bugs in the latest STABLE release
  the squid bugzilla database should be used

  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.



  The vulnerability was reported by Indarien


Revision history:

  2011-08-27 11:05 GMT Initial Version
  2011-08-27 17:31 GMT Update to include 3.0.STABEL26 release
Received on Sun Aug 28 2011 - 10:29:32 MDT

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