Squid < 3.5.6 Squid Cache Peer CONNECT Remote Access Bypass

This script is Copyright (C) 2015 Tenable Network Security, Inc.


Synopsis :

The remote proxy server is potentially affected by an authentication
bypass vulnerability.

Description :

According to its banner, the version of Squid running on the remote
host is prior to 3.5.6. It is, therefore, potentially affected by an
authentication bypass vulnerability due to a flaw in file tunnel.cc,
which is triggered whenever cache peer CONNECT responses are blindly
forwarded in a hierarchy of two or more proxies, resulting in
unrestricted access to a back-end proxy through its gateway proxy. A
remote, unauthenticated attacker, using a specially crafted request,
can exploit this vulnerability to bypass authentication or gain access
to protected resources. This issue occurs in configurations with
cache_peer enabled, and exploitation would require that the two
proxies have differing levels of security.

Note that Nessus has not tested for this issue but has instead relied
only on the application's self-reported version number. The patch
released to address this issue does not update the version in the
banner. If the patch has been applied properly, and the service has
been restarted, consider this to be a false positive.

See also :

http://www.squid-cache.org/Advisories/
http://www.squid-cache.org/Advisories/SQUID-2015_2.txt

Solution :

Upgrade to Squid versions 3.5.6 or later, or apply the vendor-supplied
patch.

Risk factor :

Low / CVSS Base Score : 2.6
(CVSS2#AV:N/AC:H/Au:N/C:P/I:N/A:N)
CVSS Temporal Score : 1.9
(CVSS2#E:U/RL:OF/RC:C)
Public Exploit Available : false

Family: Firewalls

Nessus Plugin ID: 84674 ()

Bugtraq ID:

CVE ID:

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