__________________________________________________________________ Squid Proxy Cache Security Update Advisory SQUID-2016:5 __________________________________________________________________ Advisory ID: SQUID-2016:5 Date: April 20, 2016 Summary: Buffer overflow in cachemgr.cgi Affected versions: Squid 2.x all releases Squid 3.x -> 3.5.16 Squid 4.x -> 4.0.8 Fixed in version: Squid 3.5.17, 4.0.9 __________________________________________________________________ http://www.squid-cache.org/Advisories/SQUID-2016_5.txt http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-4051 CESG REF: 56397140 / VULNERABILITY ID: 394201 __________________________________________________________________ Problem Description: Due to incorrect buffer management Squid cachemgr.cgi tool is vulnerable to a buffer overflow when processing remotely supplied inputs relayed to it from Squid. __________________________________________________________________ Severity: This problem allows any client to seed the Squid manager reports with data that will cause a buffer overflow when processed by the cachemgr.cgi tool. However, this does require manual administrator actions to take place. Which greatly reduces the impact and possible uses. __________________________________________________________________ Updated Packages: This bug is fixed by Squid versions 3.5.17 and 4.0.9 In addition, patches addressing this problem for stable releases can be found in our patch archives: Squid 3.2: Squid 3.3: Squid 3.4: Squid 3.5: 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: Squid proxy is not vulnerable. The problem is isolated to the manager CGI interface tool. The vulnerability is also limited to reports displaying full URL and/or similar unbounded values provided by the client. That includes the reports: filedescriptors, objects, vm_objects, active_requests, client_list, and mem on certain systems. cachemgr.cgi tool displays its version number in the HTML page footer: All 2.x versions up to and including 2.7.STABLE9 are vulnerable. All 3.x versions up to and including 3.5.16 are vulnerable. All 4.x versions up to and including 4.0.8 are vulnerable. If your cachemgr.cgi does not display a version it is likely to be one of the older vulnerable versions. __________________________________________________________________ Workaround: Use tools other than cachemgr.cgi, such as squidclient to view affected reports until the CGI tool can be patched or upgraded. OR, In recent Squid versions use the HTTP management interface directly from the squid proxy to view affected reports. __________________________________________________________________ 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@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@squid-cache.org mailing list. It is 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 discovered independently by CESG and by Yuriy M. Kaminskiy. Fixed by Amos Jeffries from Treehouse Networks Ltd. __________________________________________________________________ Revision history: 2016-04-15 10:54:39 GMT Initial Report 2016-04-20 03:54:54 GMT Patches Released 2016-04-20 13:42:00 GMT Packages Released 2016-04-20 15:47:01 GMT CVE Assigned __________________________________________________________________ END