Date: Tue, 22 Nov 2016 12:02:30 +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 194 (CVE-2016-9384) - guest 32-bit ELF symbol table load leaking host data -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2016-9384 / XSA-194 version 3 guest 32-bit ELF symbol table load leaking host data UPDATES IN VERSION 3 ==================== Public release. ISSUE DESCRIPTION ================= Along with their main kernel binary, unprivileged guests may arrange to have their Xen environment load (kernel) symbol tables for their use. The ELF image metadata created for this purpose has a few unused bytes when the symbol table binary is in 32-bit ELF format. These unused bytes were not properly cleared during symbol table loading. IMPACT ====== A malicious unprivileged guest may be able to obtain sensitive information from the host. The information leak is small and not under the control of the guest, so effectively exploiting this vulnerability is probably difficult. VULNERABLE SYSTEMS ================== Only Xen version 4.7 is affected. Xen versions 4.6 and earlier are not affected. The vulnerability is not exposed to x86 HVM guests, unless the host toolstack has configured to load the guest with a non-default loader, rather than hvmloader. MITIGATION ========== There is no known mitigation. CREDITS ======= This issue was discovered by Roger Pau Monné of Citrix. RESOLUTION ========== Applying the attached patch resolves this issue. xsa194.patch xen-unstable, Xen 4.7.x $ sha256sum xsa194* 4dad65417d9ff3c86e763d3c88cf8de79b58a9981d531f641ae0dd0dcedce911 xsa194.patch $ DEPLOYMENT DURING EMBARGO ========================= Deployment of the patches and/or mitigations described above (or others which are substantially similar) is permitted during the embargo, even on public-facing systems with untrusted guest users and administrators. But: Distribution of updated software is prohibited (except to other members of the predisclosure list). Predisclosure list members who wish to deploy significantly different patches and/or mitigations, please contact the Xen Project Security Team. (Note: this during-embargo deployment notice is retained in post-embargo publicly released Xen Project advisories, even though it is then no longer applicable. This is to enable the community to have oversight of the Xen Project Security Team's decisionmaking.) For more information about permissible uses of embargoed information, consult the Xen Project community's agreed Security Policy: http://www.xenproject.org/security-policy.html -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJYNDLYAAoJEIP+FMlX6CvZqAoH/39GSWwDpYnflz3TcFyQUViM j36XzzStWya71ewaXiguUbTHHg6mK47pK4EA/3zFwerczz/5yQzhlToitPkP/8WE 5Qbg9Wyg4STylzeKaiTvLzqUK6XSiJ4oKZwLsnU7tFPLcb6FBMm9t3bzg9NECaft /6zYj1SVCvoLJB/gtgbwrz2MCjVZQZ9Q2+mpirvu0ePQRD73M0cwfj1ncqjUkFd9 ZNdk14gmxOk1/wWAm/oD1QKUWmjpzByT5dbGcMV3OxGs1V2Px+o4c1u1t/agldr0 wC2LvCK9IED9JcBaH/M85TTAGR7GqfU8l9x3ep97GkrUpquX4OGFt7na28M1YUQ= =Gc8O -----END PGP SIGNATURE----- Download attachment "xsa194.patch" of type "application/octet-stream" (5732 bytes)
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