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      Squid Proxy Cache Security Update Advisory SQUID-2011:2
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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 -> 3.2.0.10
Fixed in version:       Squid 3.2.0.11, 3.1.15, 3.0.STABLE26
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     http://www.squid-cache.org/Advisories/SQUID-2011_2.txt
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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.

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Severity:

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

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Updated Packages:

 This bug is fixed by Squid version 3.2.0.11.

 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)
 http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.0-9194.patch

Squid 3.1: (transitional protection)
 http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10356.patch

Squid 3.2: (full protection)
 http://www.squid-cache.org/Versions/v3/3.2/changesets/squid-3.2-11271.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 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 3.2.0.11 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
 vulnerable.

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Workarounds:

 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.
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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@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@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:

 The vulnerability was reported by Gaiar Mukhetdinov "Indarien"

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Revision history:

 2011-08-27 11:05 GMT Initial Version
 2011-08-27 17:31 GMT Update to include 3.0.STABEL26 release
 2011-08-29 07:39 GMT Update reporter name
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