{"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\/cs\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","title":{"rendered":"Zranitelnost v k\u00f3du specifick\u00e9m pro CPU AMD v KVM, kter\u00e1 umo\u017e\u0148uje vykon\u00e1n\u00ed k\u00f3du mimo hostitelsk\u00fd syst\u00e9m","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V\u00fdzkumn\u00edci z t\u00fdmu Google Project Zero odhalili zranitelnost (CVE-2021-29657) v dod\u00e1van\u00e9m hypervizoru KVM v j\u00e1d\u0159e Linux, kter\u00e1 umo\u017e\u0148uje obej\u00edt izolaci hostitelsk\u00e9ho syst\u00e9mu a spustit sv\u016fj k\u00f3d na stran\u011b hostitelsk\u00e9ho prost\u0159ed\u00ed. Probl\u00e9m se vyskytuje v k\u00f3du pou\u017e\u00edvan\u00e9m na syst\u00e9mech s procesory AMD (modul kvm-amd.ko) a neprojevuje se na procesorech Intel. <\/p>\n

V\u00fdzkumn\u00edci vytvo\u0159ili funk\u010dn\u00ed prototyp exploitu, kter\u00fd umo\u017e\u0148uje z prost\u0159ed\u00ed hosta spustit root shell v hostitelsk\u00e9m prost\u0159ed\u00ed na syst\u00e9mu s procesorem AMD Epyc 7351P a j\u00e1drem Linux 5.10. Je zaznamen\u00e1no, \u017ee se jedn\u00e1 o prvn\u00ed zranitelnost t\u0159\u00eddy \u201eguest-to-host\u201c v samotn\u00e9m hypervizoru. KVM<\/a>, nesouvisej\u00edc\u00ed s chybami v komponent\u00e1ch b\u011b\u017e\u00edc\u00edch v u\u017eivatelsk\u00e9m prostoru, jako je QEMU. Oprava byla p\u0159ijata do j\u00e1dra na konci b\u0159ezna. Probl\u00e9m se projevuje od j\u00e1dra Linux 5.10-rc1 do v5.12-rc6, tedy pokr\u00fdv\u00e1 pouze j\u00e1dra 5.10 a 5.11 (v\u011bt\u0161ina stabiln\u00edch v\u011btv\u00ed distribuc\u00ed se tohoto probl\u00e9mu nedotkla). <\/p>\n

Probl\u00e9m se vyskytuje v mechanismu nested_svm_vmrun, implementovan\u00e9m pomoc\u00ed roz\u0161\u00ed\u0159en\u00ed AMD SVM (Secure Virtual Machine), kter\u00e9 umo\u017e\u0148uje uspo\u0159\u00e1dat vno\u0159en\u00fd spu\u0161t\u011bn\u00ed hostitelsk\u00fdch syst\u00e9m\u016f. Pro spr\u00e1vnou implementaci t\u00e9to funkcionality mus\u00ed hypervizor zachyt\u00e1vat v\u0161echny instrukce SVM vykon\u00e1van\u00e9 v hostitelsk\u00fdch syst\u00e9mech, emulovat jejich chov\u00e1n\u00ed a synchronizovat stav s hardwarem, co\u017e je pom\u011brn\u011b slo\u017eit\u00fd \u00fakol. Po anal\u00fdze implementace v KVM v\u00fdzkumn\u00edci na\u0161li logickou chybu, kter\u00e1 umo\u017e\u0148uje ovlivnit obsah registr\u016f MSR (Model-Specific Register) hostitele z hostitelsk\u00e9ho syst\u00e9mu, co\u017e lze vyu\u017e\u00edt k spu\u0161t\u011bn\u00ed k\u00f3du na \u00farovni hostitele. <\/p>\n

Konkr\u00e9tn\u011b proveden\u00ed operace VMRUN z hostitelsk\u00e9ho syst\u00e9mu druh\u00e9 \u00farovn\u011b (L2, spu\u0161t\u011bn\u00e9ho z jin\u00e9ho hostitelsk\u00e9ho syst\u00e9mu) vede k druh\u00e9mu vol\u00e1n\u00ed nested_svm_vmrun a po\u0161kozen\u00ed struktury svm->nested.hsave, na kterou se na\u0159izuj\u00ed data z vmcb hostitelsk\u00e9ho syst\u00e9mu L2. V d\u016fsledku toho vznik\u00e1 situace, kdy na \u00farovni hostitelsk\u00e9ho syst\u00e9mu L2 lze uvolnit pam\u011b\u0165 ve struktu\u0159e svm->nested.msrpm, ve kter\u00e9 je ulo\u017een bit MSR, p\u0159esto\u017ee se nad\u00e1le pou\u017e\u00edv\u00e1, a z\u00edskat p\u0159\u00edstup k MSR hostitelsk\u00e9ho prost\u0159ed\u00ed.
\n
Zdroj: 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\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\udd47Zranitelnost ve specifick\u00e9m k\u00f3du KVM pro CPU AMD, kter\u00e1 umo\u017e\u0148uje vykon\u00e1vat k\u00f3d mimo hostitelsk\u00fd syst\u00e9m | ProHoster","description":"V\u00fdzkumn\u00edci z t\u00fdmu Google Project Zero odhalili zranitelnost (CVE-2021-29657) v hypervizoru KVM dod\u00e1van\u00e9m v j\u00e1dru Linuxu, kter\u00e1 umo\u017e\u0148uje obej\u00edt 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