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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.1845 Xen Security Advisory CVE-2015-3259 / XSA-137 13 July 2015 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Xen Publisher: Xen Operating System: UNIX variants (UNIX, Linux, OSX) Xen Impact/Access: Increased Privileges -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2015-3259 Original Bulletin: http://xenbits.xen.org/xsa/advisory-137.html - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2015-3259 / XSA-137 version 3 xl command line config handling stack overflow UPDATES IN VERSION 3 ==================== Public release. ISSUE DESCRIPTION ================= The xl command line utility mishandles long configuration values when passed as command line arguments, with a buffer overrun. VULNERABLE SYSTEMS ================== Systems built on top of xl which pass laundered or checked (but otherwise untrusted) configuration values onto xl's command line, without restricting their length, are vulnerable. We are not presently aware of any publicly distributed production software which exposes the xl vulnerability. However it is sufficiently simple to create such an arrangement that it might be done locally in an attempt to grant partial management access to particular domains. Systems using the libxl library directly, without using xl, are not vulnerable. Systems using toolstacks other than xl are not vulnerable. Systems where only fully trusted input is ever presented to the xl command line are not vulnerable. The vulnerability exists on x86 and ARM. The vulnerability was introduced in Xen 4.1 and affects all subsequent Xen releases. IMPACT ====== A semi-trusted guest administrator or controller, who is intended to be able to partially control the configuration settings for a domain, can escalate their privileges to that of the whole host. MITIGATION ========== Limiting the length of untrusted configuration settings will avoid the vulnerability. (The total length of all command-line configuration settings, including some interposed newlines and trailing nul, must be less than 1024.) CREDITS ======= This issue was discovered by Donghai Zhu of Alibab. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa137.patch Xen 4.2.x and later $ sha256sum xsa137*.patch 0272c443575c88b53445c89ef84f0cd98a03944d3303f06c66c33ef0037d97b9 xsa137.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 v1.4.12 (GNU/Linux) iQEcBAEBAgAGBQJVm8UeAAoJEIP+FMlX6CvZmnEH/1Tq+nP7STM4yE56JJsqUikV HmKbJuCy6yApsMQ7JrPjbs3yo826OQl3BVyZBicfgk6B2Cx78QgbF+XGK6B/9sfz DP5bMwz9S4n5u7K4bMkppx+6p2nG06hkzfdwzGbCC3nKiW9chYo4NdPtcQRA4d2d LnSN7JGJjxAFq22a3KKlb5AILr6x/+PYPan/jolf39rXmU1Lcg0fsMFuLm8fK1MQ burOoCphm8Xd0UOgNaH2BGCAjYoFuxKC7n12u9poCFQpnyKsYI7YGvLI2X6NgHOZ PRRSsuWqf0g7huzM/UkvPthCJzxmPWPqrLoBVOuspAOFVcqwqDmdKKSjcppEV+Q= =rvRm - -----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 iQIVAwUBVaNHHn6ZAP0PgtI9AQK3OQ//QtcWXylOGVsMzOAWJhhCk6Ld8PZFdSod kO0OedXjfcY3dLoyJaqTXFbTTkK0XdJ8q2Umc6sMDTM17l6E+CYFzY0NPAjX4mTk MFsA2s9vH6z2oosyosPl2xPWqxRumhuu5q7niMD6T9LIFW0wR46QjPW+hCyj4M6N UF8SPnFwZ5vuavhi0CEKNi96lmQo9NRXJ2j4InXiolYHuWjyxtIHfGeZm5AvqMsq ZeqDfiw3JrJil0KQedpfv7Q1hu1eKIP/ACee6bUGEkbuyrTvgyU8P2nmhy/tr+ta YVlDxbY+YsogDPGCwPwyEt5Rd+Xhz8VcnA2EO6BOLbp5M+pEitBA6gbBV4rtctwZ CHvcB9q2XO8mnwL1L0RtVC4yp+FT6NJRiTSQRWzYeaObbztYG+IE2btWNuxHxyNx kc1HAqOtTXEL9eexqxeScgUJiG2ROmxcakRvNWB876Lj7ldZHo1eO+0Jv+tfs4L4 EWGxlJRgRtgrZv2VmxqYuB4+v8dpb7rJn/tQlTjJ4qsdmnbX/5aaImxYCeIpXQ4k p8+qIoKYfayBN5u8QpIMJp5gfr2ELerxzMZhgEXTLdTHN8co7sg+5gVDOmVwqnUY LWeQ4loFcqspkaKztiK4lfbLWdUWesEf955dN+wr4/K1ckzRdIm4hucVjMT0oayx 6ZqsOCRm2mM= =e0nT -----END PGP SIGNATURE-----