__________________________________________________________________ Squid Proxy Cache Security Update Advisory SQUID-2015:2 __________________________________________________________________ Advisory ID: SQUID-2015:2 Date: July 06, 2015 Summary: Improper Protection of Alternate Path Affected versions: Squid 0.x -> 3.5.5 Fixed in version: Squid 3.5.6 __________________________________________________________________ http://www.squid-cache.org/Advisories/SQUID-2015_2.txt http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-5400 __________________________________________________________________ Problem Description: Squid configured with cache_peer and operating on explicit proxy traffic does not correctly handle CONNECT method peer responses. __________________________________________________________________ Severity: The bug is important because it allows remote clients to bypass security in an explicit gateway proxy. However, the bug is exploitable only if you have configured cache_peer to receive CONNECT requests. __________________________________________________________________ Updated Packages: This bug is fixed by Squid version 3.5.6. In addition, patches addressing this problem for stable releases can be found in our patch archives: Squid 3.1: http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10494.patch Squid 3.4: http://www.squid-cache.org/Versions/v3/3.4/changesets/squid-3.4-13225.patch Squid 3.5: http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13856.patch If you are using a prepackaged version of Squid then please refer to the package vendor for availability information on updated packages. __________________________________________________________________ Determining if your version is vulnerable: All Squid versions with cache_peer omitted from squid.conf are not vulnerable to the problem. All Squid versions with squid.conf containing "nonhierarchical_direct on" are not vulnerable to the problem. All Squid-3.1 and later with nonhierarchical_direct omitted from squid.conf are not vulnerable to the problem. All other unpatched Squid configured to use a cache_peer without the "originserver" option are vulnerable to the problem. __________________________________________________________________ Workaround: For Squid-3.0 and older ensure squid.conf contains "nonhierarchical_direct on". For Squid-3.1 and newer remove nonhierarchical_direct from squid.conf. __________________________________________________________________ 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 you install and build Squid from the original Squid sources then the squid-users@lists.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 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@lists.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. __________________________________________________________________ Credits: The vulnerability was reported and fixed by Alex Rousskov, The Measurement Factory. Squid-3.1 backport by Raphaƫl Hertzog, Debian Project. __________________________________________________________________ Revision history: 2015-06-16 16:54 GMT Initial Report and Patches Released 2015-05-03 15:37 GMT Packages Released 2015-07-17 14:09 GMT CVE Assigment 2015-07-30 15:57 GMT Patch for 3.1 added __________________________________________________________________ END