{"id":100636,"date":"2021-06-30T22:23:10","date_gmt":"2021-06-30T20:23:10","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy"},"modified":"2021-06-30T22:23:10","modified_gmt":"2021-06-30T20:23:10","slug":"uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","status":"publish","type":"post","link":"https:\/\/prohoster.info\/fr\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","title":{"rendered":"Vuln\u00e9rabilit\u00e9 dans le code KVM sp\u00e9cifique aux processeurs AMD, permettant d'ex\u00e9cuter du code en dehors du syst\u00e8me invit\u00e9","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Des chercheurs de l'\u00e9quipe Google Project Zero ont identifi\u00e9 une vuln\u00e9rabilit\u00e9 (CVE-2021-29657) dans l'hyperviseur KVM inclus dans le noyau Linux, permettant de contourner l'isolation du syst\u00e8me invit\u00e9 et d'ex\u00e9cuter du code du c\u00f4t\u00e9 de l'environnement h\u00f4te. Le probl\u00e8me est pr\u00e9sent dans le code utilis\u00e9 sur les syst\u00e8mes avec des processeurs AMD (module kvm-amd.ko) et ne se manifeste pas pour les processeurs Intel. <\/p>\n

Des chercheurs ont pr\u00e9par\u00e9 un prototype fonctionnel d'exploit permettant de lancer un shell root dans l'environnement h\u00f4te depuis un environnement invit\u00e9 sur un syst\u00e8me avec un processeur AMD Epyc 7351P et un noyau Linux 5.10. Il est not\u00e9 qu'il s'agit de la premi\u00e8re vuln\u00e9rabilit\u00e9 de la classe \u00ab guest-to-host \u00bb dans l'hyperviseur lui-m\u00eame. KVM<\/a>, non li\u00e9e \u00e0 des erreurs dans des composants ex\u00e9cut\u00e9s dans l'espace utilisateur, tels que QEMU. Le correctif a \u00e9t\u00e9 int\u00e9gr\u00e9 au noyau fin mars. Le probl\u00e8me appara\u00eet \u00e0 partir du noyau Linux 5.10-rc1 et se termine avec v5.12-rc6, c'est-\u00e0-dire qu'il concerne uniquement les noyaux 5.10 et 5.11 (la plupart des branches stables des distributions ne sont pas touch\u00e9es par le probl\u00e8me). <\/p>\n

Le probl\u00e8me est pr\u00e9sent dans le m\u00e9canisme nested_svm_vmrun, mis en \u0153uvre en utilisant l'extension AMD SVM (Secure Virtual Machine) et permettant d'organiser le lancement imbriqu\u00e9 de syst\u00e8mes invit\u00e9s. Pour une mise en \u0153uvre correcte de cette fonctionnalit\u00e9, l'hyperviseur doit intercepter toutes les instructions SVM ex\u00e9cut\u00e9es dans les syst\u00e8mes invit\u00e9s, \u00e9muler leur comportement et synchroniser l'\u00e9tat avec le mat\u00e9riel, ce qui repr\u00e9sente une t\u00e2che assez complexe. En analysant la mise en \u0153uvre propos\u00e9e dans KVM, les chercheurs ont trouv\u00e9 une erreur logique permettant d'influer sur le contenu des registres MSR (Model-Specific Register) de l'h\u00f4te depuis le syst\u00e8me invit\u00e9, ce qui peut \u00eatre utilis\u00e9 pour ex\u00e9cuter du code au niveau de l'h\u00f4te. <\/p>\n

En particulier, l'ex\u00e9cution de l'op\u00e9ration VMRUN depuis un syst\u00e8me invit\u00e9 de niveau deux (L2, lanc\u00e9 depuis un autre syst\u00e8me invit\u00e9) entra\u00eene un second appel \u00e0 nested_svm_vmrun et endommage la structure svm->nested.hsave, sur laquelle sont superpos\u00e9es les donn\u00e9es de vmcb du syst\u00e8me invit\u00e9 L2. Cela cr\u00e9e une situation o\u00f9, au niveau du syst\u00e8me invit\u00e9 L2, il est possible de lib\u00e9rer de la m\u00e9moire dans la structure svm->nested.msrpm, o\u00f9 est stock\u00e9 le bit MSR, m\u00eame s'il continue d'\u00eatre utilis\u00e9, et d'acc\u00e9der au MSR de l'environnement h\u00f4te.
\n
Source : opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0418\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0438 \u0438\u0437 \u043a\u043e\u043c\u0430\u043d\u0434\u044b Google Project Zero \u0432\u044b\u044f\u0432\u0438\u043b\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-29657) \u0432 \u043f\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u043e\u043c \u0432 \u0441\u043e\u0441\u0442\u0430\u0432\u0435 \u044f\u0434\u0440\u0430 Linux \u0433\u0438\u043f\u0435\u0440\u0432\u0438\u0437\u043e\u0440\u0435 KVM, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0443\u044e \u043e\u0431\u043e\u0439\u0442\u0438 \u0438\u0437\u043e\u043b\u044f\u0446\u0438\u044e \u0433\u043e\u0441\u0442\u0435\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b \u0438 \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u0441\u0432\u043e\u0439 \u043a\u043e\u0434 \u043d\u0430 \u0441\u0442\u043e\u0440\u043e\u043d\u0435 \u0445\u043e\u0441\u0442-\u043e\u043a\u0440\u0443\u0436\u0435\u043d\u0438\u044f. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u0438\u0441\u0443\u0442\u0441\u0442\u0432\u0443\u0435\u0442 \u0432 \u043a\u043e\u0434\u0435, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c\u043e\u043c \u043d\u0430 \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u0445 \u0441 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0440\u0430\u043c\u0438 AMD (\u043c\u043e\u0434\u0443\u043b\u044c kvm-amd.ko) \u0438 \u043d\u0435 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0434\u043b\u044f \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0440\u043e\u0432 Intel. \u0418\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044f\u043c\u0438 \u043f\u043e\u0434\u0433\u043e\u0442\u043e\u0432\u043b\u0435\u043d \u0440\u0430\u0431\u043e\u0447\u0438\u0439 \u043f\u0440\u043e\u0442\u043e\u0442\u0438\u043f \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0439 \u0438\u0437 \u0433\u043e\u0441\u0442\u0435\u0432\u043e\u0433\u043e […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-100636","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Vuln\u00e9rabilit\u00e9 dans le code KVM sp\u00e9cifique aux processeurs AMD, permettant d'ex\u00e9cuter du code en dehors du syst\u00e8me invit\u00e9 | ProHoster","description":"Des chercheurs de l'\u00e9quipe Google Project Zero ont identifi\u00e9 une vuln\u00e9rabilit\u00e9 (CVE-2021-29657) dans l'hyperviseur KVM int\u00e9gr\u00e9 au noyau Linux, permettant de 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