Date: Fri, 07 Sep 2012 19:33:42 +0000 From: "Nathan March" <nathan@...net> To: "Xen.org security team" <security@....org>, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com Cc: "Xen.org security team" <security@....org> Subject: Re: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability Hi All, I'm guessing this wasn't intentional, but the patch for xsa17 does not contain a complete path to the tools/ioemu-qemu-xen/ path: --- a/console.c +++ b/console.c Compared to all the other patches which provide a full path to the patched file: --- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100 +++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100 Little annoying since it means you have to track down which console.c is being patched instead of just applying from the root xen build dir. - Nathan ------ Original Message ------ 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> Sent: 9/5/2012 4:12:47 AM Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability >-----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA1 > > Xen Security Advisory CVE-2012-3515 / XSA-17 > version 2 > > Qemu VT100 emulation vulnerability > >UPDATES IN VERSION 2 >==================== > >Public release. > >ISSUE DESCRIPTION >================= > >The device model used by fully virtualised (HVM) domains, qemu, does >not properly handle escape VT100 sequences when emulating certain >devices with a virtual console backend. > >IMPACT >====== > >An attacker who has sufficient privilege to access a vulnerable device >within a guest can overwrite portions of the device model's address >space. This can allow them to escalate their privileges to that of the >device model process. > >VULNERABLE SYSTEMS >================== > >All Xen systems running HVM guests are potentially vulnerable to this >depending on the specific guest configuration. The default >configuration is vulnerable. > >Guests using either the traditional "qemu-xen" or upstream qemu device >models are vulnerable. > >MITIGATION >========== > >This issue can be avoided by only running PV guests or by configuring >HVM guests to not use the virtual console('vc') backend for any device. > >For serial devices specify in your guest configuration: > serial = 'none' >in your guest configuration. > >For parallel port devices the syntax is toolstack specific. >For xend specify in your guest configuration: > parallel = 'none' >For xl specify in your guest configuration: > xl: device_model_args = ['-parallel', 'none'] > >In both cases the default is to use the vulnerable 'vc' mode. > >You can confirm whether or not you are vulnerable by pressing >Ctrl-Alt-<N> (for digit N) while connected to either the VNC or SDL >console. If you are able to switch to a window displaying "serial" or >"parallel" then you are vulnerable. > >The issue can also be mitigated by enabling the stub domain device >model. In this case the attacked can only potentially gain control of >the stub domain and not of the entire system. > >To enable stub domains specify in your guest configuration: > device_model = "stubdom-dm" > >RESOLUTION >========== > >Applying the appropriate attached patch(es) will resolve the issue. > >PATCH INFORMATION >================= > >The attached patches resolve this issue > >Traditional qemu tree > Xen 4.0, 4.1 and unstable xsa17-qemu-xen-traditional-all.patch > >Upstream qemu tree (present in unstable only) > Xen unstable xsa17-qemu-xen-unstable.patch > >$ sha256sum xsa17-*.patch >60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 xsa17-qemu-xen-traditional-all.patch >7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 xsa17-qemu-xen-unstable.patch >-----BEGIN PGP SIGNATURE----- >Version: GnuPG v1.4.10 (GNU/Linux) > >iQEcBAEBAgAGBQJQRx1PAAoJEIP+FMlX6CvZUqUH/jeAAvQnoBp6YKzm78XSnnmk >GI2C/LhH0xqR3wFoEmWeMsiO4lrGrASX6T31NTvHa8sOtFqlNpTfRhwQybwYR3aa >cz9/4y2a54hD95P1nVmPF0PddmSP47QSpRdCj0projq1UGxIdwEhkNeSoM8h7dXO >MegqZClsvJMKd8XEcjBF5Qg7u9vLrXilCx5+It7XNE31Jxpkr/fozBb7FnNtDGJj >s4RN/UDU4Pu68XyZ7Dc5xEFdJW48tz4BIlxxXavILBRFSE1VEf7Gc8H9CsUtBPWB >C/LCUjpHkAOmqdgFhiLnZ2u+2s79U0dtPDJMNmqaGgWH+AqGkU9Nq8XXODTyY9k= >=gnuE >-----END PGP SIGNATURE----- > >
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