Date: Mon, 11 Nov 2013 11:42:37 +0000 From: Xen.org security team <security@....org> To: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com CC: Xen.org security team <security@....org> Subject: Xen Security Advisory 75 (CVE-2013-4551) - Host crash due to guest VMX instruction execution -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2013-4551 / XSA-75 version 2 Host crash due to guest VMX instruction execution UPDATES IN VERSION 2 ==================== This issue has been assigned CVE-2013-4551. ISSUE DESCRIPTION ================= Permission checks on the emulation paths (intended for guests using nested virtualization) for VMLAUNCH and VMRESUME were deferred too much. The hypervisor would try to use internal state which is not set up unless nested virtualization is actually enabled for a guest. IMPACT ====== A malicious or misbehaved HVM guest, including malicious or misbehaved user mode code run in the guest, might be able to crash the host. VULNERABLE SYSTEMS ================== Xen 4.2.x and later are vulnerable. Xen 4.1.x and earlier are not vulnerable. Only HVM guests run on VMX capable (e.g. Intel) hardware can take advantage of this vulnerability. MITIGATION ========== Running only PV guests, or running HVM guests on SVM capable (e.g. AMD) hardware will avoid this issue. Enabling nested virtualization for a HVM guest running on VMX capable hardware would also allow avoiding the issue. However this functionality is still considered experimental, and is not covered by security support from the Xen Project security team. This approach is therefore not recommended for use in production. CREDITS ======= This issue was discovered by Jeff Zimmerman. NOTE REGARDING LACK OF EMBARGO ============================== This issue was disclosed publicly on the xen-devel mailing list. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa75-4.3-unstable.patch Xen 4.3.x, xen-unstable xsa75-4.2.patch Xen 4.2.x $ sha256sum xsa75*.patch 5d7bd39e4077dcdf97abf8cf3ceb662403bedf8642ce7d15840b329bc9e56727 xsa75-4.2.patch 7e61b457c9ad8d7c598d88163d2760041033ddb1631cfe989f853b7c2b5cd0bf xsa75-4.3-unstable.patch $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAEBAgAGBQJSgMKZAAoJEIP+FMlX6CvZNC0H/0DZ1mBOiGpfSsn+HjCQuVup U81kWQp+SjVKVWvJbG+/vdL/418gIJ/jS9PzL7Qhordb63l7fq1d+Gi9vsQApnku 25/rKpFQzbJCud/67P3DyO3RAw33z5rQ+S/7nLLx7K6oDKNS3knQpcQwjeNIH040 NekPA2qBEuIi/0G72fYzU1wzc5XWve3lftzgYVyW+CFE1CUDq9OdWxHm5FTI41TH v1/WURQelw4a6BTVvV6NxK8J4ibQvWpL0Id4kXs1DnrSl39Al6gBUf2dO/JQwjCo fxMMjFAqWtpOrJjbWntUSJSzsFp/UfIh23a2AEmgdo4H/5yRG5RnomgSw2jOjw8= =gTUt -----END PGP SIGNATURE----- Download attachment "xsa75-4.2.patch" of type "application/octet-stream" (1602 bytes) Download attachment "xsa75-4.3-unstable.patch" of type "application/octet-stream" (1763 bytes)
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