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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2013.1370 Xen Security Advisory CVE-2013-1442 / XSA-62 version 2 1 October 2013 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Xen Publisher: Xen Operating System: Xen UNIX variants (UNIX, Linux, OSX) Impact/Access: Access Privileged Data -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2013-1442 Original Bulletin: http://xenbits.xen.org/xsa/advisory-62.txt - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2013-1442 / XSA-62 version 2 Information leak on AVX and/or LWP capable CPUs UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= When a guest increases the set of extended state components for a vCPU saved/ restored via XSAVE/XRSTOR (to date this can only be the upper halves of YMM registers, or AMD's LWP state) after already having touched other extended registers restored via XRSTOR (e.g. floating point or XMM ones) during its current scheduled CPU quantum, the hypervisor would make those registers accessible without discarding the values an earlier scheduled vCPU may have left in them. IMPACT ====== A malicious domain may be able to leverage this to obtain sensitive information such as cryptographic keys from another domain. VULNERABLE SYSTEMS ================== Xen 4.0 and onwards are vulnerable when run on systems with processors supporting AVX and/or LWP. Any kind of guest can exploit the vulnerability. In Xen 4.0.2 through 4.0.4 as well as in Xen 4.1.x XSAVE support is disabled by default; therefore systems running these versions are not vulnerable unless support is explicitly enabled using the "xsave" hypervisor command line option. Systems using processors supporting neither AVX nor LWP are not vulnerable. Xen 3.x and earlier are not vulnerable. MITIGATION ========== Turning off XSAVE support via the "no-xsave" hypervisor command line option will avoid the vulnerability. CREDITS ======= Jan Beulich discovered this issue. RESOLUTION ========== Applying the attached patch resolves this issue. xsa62.patch Xen 4.2.x, 4.3.x, and unstable xsa62-4.1.patch Xen 4.1.x $ sha256sum xsa62*.patch 3cec8ec26552f2142c044422f1bc0f77892e681d789d1f360ecc06e1d714b6bb xsa62-4.1.patch 364577f317a714099c068eb1ab771643ada99b5067fdd1eb5149fa5db649b856 xsa62.patch $ - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAEBAgAGBQJSQp1tAAoJEIP+FMlX6CvZvMYIAKe6fyuMdVlP3gJVqAnttQb7 E/TuXwIKBgUFNu34SdkGd6g1l13pfSeiovDD56SqNj5kwCD0rb6+LgHu/uqVsxSn w+JtPGFXQpAfNzEcDPqYP9ArJIp63ogC9CLwk9KcDoy0FnxpHFD3Ke5C62G83DAJ qhjEpknTQCwjXBG6fYXjYKhFR8kzkWHGRpECE3EwlLo1gWxQj8/p/TopY8kzmA5m ssDuM/XzBHjI+7NwiB5oNuZfS8Om+UVQUilv+bjarh9zJy55FGSL1gJzdcXGhFx5 sXw/PcciIAcCC8k8f2+tYY1eN9Orthw81YMh9Q/n6JC4RMgBYK3tkZ9AsOR7H9s= =Qbk6 - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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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 iQIVAwUBUkpPHhLndAQH1ShLAQJAhg/+L1sZJ6uM11rXDli2ukrOpWH4Q3VlpvuD NASTx3jQge+eoMU+rzhR+m/ldYtgtdYlYePatZkh1xbLv5sxSUhg9bG0JBflub2K 5Bc9RgDGKLEh5HdBIrucP5Ziu4zkqm2EySGFsFqcCOX9MM1Bp4PxG4pM2EimmqL4 Cfu6l8CQewvvUNoFtmGrsPZ11gflzPoEh2JT1PFuFKK0OVSvtNPARP/ll8pQjqvz geKnynrPFuSDMrXGcCg+2AHCi3BCXvUPhQjaAjXNw39i42FFLil/xOHeRgpBXD08 7GZLpduhXxtV5BJIeZgHGMYqaNaMt7KXEljYMF8bekSPO0V6NYOVNhudGw8injEU iqRHh2A7G+KjGR/WDg7A+bbXNT7WF5Nd4mBmsFcDPAsCRINya9DWO2SqHA84+Vaq GSYYRQ6crXJIRuGLx5aNPLdynaf/xHDkxk/PCDMxsHPiihO/3Ewdopt53BYxr63+ G15uID4HxYktFV+5yaqC3aE+KY4nKQ4Pw+6WEF8sZa3loa7kV5BabCAzFidVdtow nVsKA7J2Q77FAphZkamUTSBNfDvPCdnhE/wyaYw06H/O0C+UCmgwuOTnuriDpstn IKywveZ+fOoEeM8yN70rcl5zbOES8LTZa5VqEYPAjkZe//AqFg2xuArgdTc5+2Cn Ofr/sexqE+A= =pgsD -----END PGP SIGNATURE-----