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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@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx 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 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
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