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Squid Proxy Cache Security Update Advisory SQUID-2011:1
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Advisory ID: SQUID-2011:1
Date: August 27, 2011
Summary: Bypass of browser same-origin access
control in intercepted communication
Affected versions: Squid 1.x -> 3.1
Squid 3.2 -> 3.2.0.10
Fixed in version: Squid 3.2.0.11
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http://www.squid-cache.org/Advisories/SQUID-2011_1.txt
http://cve.mitre.org/cgi-bin/cvename.cgi?name=2009-0801
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Problem Description:
Due to Squid not reusing the original destination address on
intercepted requests it's possible (even trivial) for flash or
java applets to bypass the same-origin policy in the browser
when Squid intercepts HTTP requests.
The cause to this is that such applets are allowed to perform
their own HTTP stack, in which case the same-origin policy of
the browser sandbox only verifies that the applet tries to
contact the same IP as from where it was loaded at the IP level.
Squid then uses the Host header to determine which server to
forward the request to which may be different from the
connected IP.
Applies to all Squid releases up to and including 3.2.0.10.
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Severity:
This problem allows any browser script to bypass local security
and retrieve arbitrary content from any source.
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Updated Packages:
This bug is fixed by Squid versions 3.2.0.11
Due to the design of request handling processes in older Squid
patches and fixed releases for older versions of Squid are not
being provided at this time.
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 client browsers.
All Squid releases of any series up to 3.2.0.10 using the
http_port 'transparent', 'intercept' or 'tproxy' flags are
active vectors for this browser vulnerability.
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Workarounds:
Turn off NAT and TPROXY interception. Including the http_port
'transparent', 'intercept' or 'tproxy' flags in squid.conf.
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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:
Thanks to Netspace Ltd and Treehouse Networks Ltd for sponsoring
the architectural changes in Squid-3.2 leading to this solution.
Thanks to Henrik Nordstrom and Steven Wilton for initial diagnosis.
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Revision history:
2011-08-27 10:06 GMT Initial version
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