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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2016.0487.2 Squid Proxy Cache Security Update Advisory SQUID-2016:2 29 February 2016 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Squid Publisher: Squid Operating System: Windows UNIX variants (UNIX, Linux, OSX) Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2016-2572 CVE-2016-2571 CVE-2016-2570 CVE-2016-2569 Original Bulletin: http://www.squid-cache.org/Advisories/SQUID-2016_2.txt Comment: This advisory references vulnerabilities in products which run on platforms other than Squid. It is recommended that administrators running Squid check for an updated version of the software for their operating system. Revision History: February 29 2016: CVEs assigned to vulnerabilities February 25 2016: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- __________________________________________________________________ Squid Proxy Cache Security Update Advisory SQUID-2016:2 __________________________________________________________________ Advisory ID: SQUID-2016:1 Date: February 23, 2016 Summary: Multiple Denial of Service issues in HTTP Response processing. Affected versions: Squid 3.x -> 3.5.16 Squid 4.x -> 4.0.7 Fixed in version: Squid 4.0.7, 3.5.15 __________________________________________________________________ http://www.squid-cache.org/Advisories/SQUID-2016_2.txt http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2569 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2570 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2571 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2572 __________________________________________________________________ Problem Description: Due to incorrect bounds checking Squid is vulnerable to a denial of service attack when processing HTTP responses. Due to incorrect error handling Squid-4 is vulnerable to a denial of service attack when processing malformed HTTP responses. __________________________________________________________________ Severity: These problems allow remote servers delivering certain unusual HTTP response syntax to trigger a denial of service for all clients accessing the Squid service. HTTP responses containing malformed headers that trigger this issue are becoming common. We are not certain at this time if that is a sign of malware or just broken server scripting. Details of a trivial attack are already circulating publicly. __________________________________________________________________ Updated Packages: These bugs are fixed by Squid version 3.5.15 and 4.0.7. In addition, patches addressing these problems for the stable release can be found in our patch archives: Squid 3.5: http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13990.patch http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13991.patch http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13993.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-3.2 and older have not been tested but are expected to be vulnerable. All unpatched Squid-3.3 versions are vulnerable. All unpatched Squid-3.4 versions are vulnerable. All unpatched Squid-3.5.14 and older are vulnerable. All unpatched Squid-4.0.6 and older are vulnerable. __________________________________________________________________ Workaround: There are no good workarounds known for these vulnerabilities. The following squid.conf settings can protect Squid-3.5 (only) against the publicly published attack. But unpatched Squid remain vulnerable to other known attacks: acl Vary rep_header Vary . store_miss deny Vary Or, The following squid.conf settings can protect against the publicly published attack. But unpatched Squid remain vulnerable to other known attacks: cache deny all __________________________________________________________________ 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@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 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@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: CVE-2016-2569 bounds checking vulnerability was identified and reported by Mathias Fischer from Open Systems AG. Fixed by Alex Rousskov from The Measurement Factory. CVE-2016-2571, CVE-2016-2572 error handling vulnerability was found and fixed by Alex Rousskov from The Measurement Factory. CVE-2016-2570 bounds checking vulnerability was found and fixed by William Lima. __________________________________________________________________ Revision history: 2016-02-17 06:51:25 UTC Initial Report 2016-02-18 04:15:33 UTC Patches Released 2016-02-19 23:15:41 UTC Additional Patches Released 2016-02-23 16:37:27 UTC Attack PoC becomes public knowledge 2016-02-23 18:23:00 UTC Packages Released 2016-02-26 06:45:42 UTC CVE Assignment and additional patch referenced __________________________________________________________________ - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBVtOfHn6ZAP0PgtI9AQKzVA/9HJG5KMv3+5fPeq4vv54/3fBpZcWEetFP xwMIYDZGoJcl0oP+DrR4y9PE9WkAWK+4bkMAjQGETVnVKVXNuOOU2qDPKf1IMlvx hecpRTyVhTLWalXCIgZsdNfcHkJ3XMBwPUJNWiYu588UJFkUkHNUCQ0v4yO7LaZ6 tJ72StcjvkKuoofLI/22ik0+lWQ9lpTHasnr7hjLBW7S1uDj2S9WjwxIdHopOgJV m0tf3FJaXMIntfwENIquSF4GFfw4KQelnCfmIBh3bcTaTJD2Hb/7wbig69TmBrn0 PTmuuTFEtijLjdA9c0mEZXPVCqYUarANzgPOclhYqmsYvPV4vH8Tv9tF6tdKo7ha zkZL87p3/fhDHm5QluTVGbFUlf8hNJISTu9DtwU6TRVOO6T2cJ6fd/kfztkaQNAw dfN5/dYS0bCapUwRaH2bd3vHfpuWj3PUEzLNG/WFk5/SX55Zm4fcbTvdm/nPrNKI 3/LB+x00tJIQQ7WZ6s12BH0N5FJO7PeovLVB01LBJyxKIeOPasd0CFN0QY5GtZ2v MBxRR1rpUZ5ThwWCWoW1IdXEV2pBPXMCK+2z77ifc2uWCmvwiwKfpjQJxmrnoqab E5I0NCem0NKPk1db9JbJQKR/B4VnX0uSSqEi4Ly5mceggrEMyx+xCXE1WJx9uqA6 DQFElUEUqBI= =IDMX -----END PGP SIGNATURE-----