{"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\/pl\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","title":{"rendered":"Luka w specyficznym dla CPU kodzie AMD KVM, kt\u00f3ra pozwala na wykonanie kodu poza systemem go\u015bcia","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Badacze z zespo\u0142u Google Project Zero zidentyfikowali luk\u0119 (CVE-2021-29657) w hipernadzorze KVM dostarczanym w j\u0105drze Linux, kt\u00f3ra umo\u017cliwia obej\u015bcie izolacji systemu go\u015bcia i wykonanie w\u0142asnego kodu w \u015brodowisku hosta. Problem wyst\u0119puje w kodzie u\u017cywanym w systemach z procesorami AMD (modu\u0142 kvm-amd.ko) i nie wyst\u0119puje na procesorach Intel. <\/p>\n

Badacze opracowali roboczy prototyp exploita, kt\u00f3ry umo\u017cliwia uruchomienie pow\u0142oki root w \u015brodowisku hosta z poziomu \u015brodowiska go\u015bcinnego na systemie z procesorem AMD Epyc 7351P i j\u0105drem Linux 5.10. Zauwa\u017cono, \u017ce jest to pierwsza luka klasy \u201eguest-to-host\u201d w samym hipernadzorze. KVM<\/a>, niezwi\u0105zana z b\u0142\u0119dami w komponentach dzia\u0142aj\u0105cych w przestrzeni u\u017cytkownika, takich jak QEMU. Poprawka zosta\u0142a wprowadzona do j\u0105dra pod koniec marca. Problem wyst\u0119puje od j\u0105dra Linux 5.10-rc1 do v5.12-rc6, co oznacza, \u017ce dotyczy tylko j\u0105der 5.10 oraz 5.11 (wi\u0119kszo\u015b\u0107 stabilnych ga\u0142\u0119zi dystrybucji nie dotkn\u0119\u0142a tego problemu). <\/p>\n

Problem wyst\u0119puje w mechanizmie nested_svm_vmrun, zrealizowanym przy u\u017cyciu rozszerzenia AMD SVM (Secure Virtual Machine), kt\u00f3ry umo\u017cliwia zagnie\u017cd\u017cone uruchamianie system\u00f3w go\u015bci. Aby prawid\u0142owo wdro\u017cy\u0107 t\u0119 funkcjonalno\u015b\u0107, hipernadzorca musi przechwytywa\u0107 wszystkie instrukcje SVM wykonywane w systemach go\u015bci, emulowa\u0107 ich zachowanie i synchronizowa\u0107 stan z sprz\u0119tem, co jest do\u015b\u0107 z\u0142o\u017conym zadaniem. Analizuj\u0105c realizacj\u0119 w KVM, badacze znale\u017ali b\u0142\u0105d logiczny, kt\u00f3ry pozwala na wp\u0142ywanie na zawarto\u015b\u0107 rejestr\u00f3w MSR (Model-Specific Register) hosta z systemu go\u015bcia, co mo\u017ce by\u0107 wykorzystane do uruchamiania kodu na poziomie hosta. <\/p>\n

W szczeg\u00f3lno\u015bci, wykonanie operacji VMRUN z go\u015bcinnego systemu drugiego poziomu (L2, uruchomionego z innego systemu go\u015bcinnego) prowadzi do drugiego wywo\u0142ania nested_svm_vmrun i uszkodzenia struktury svm->nested.hsave, do kt\u00f3rej nak\u0142adane s\u0105 dane z vmcb go\u015bcinnego systemu L2. W rezultacie powstaje sytuacja, w kt\u00f3rej na poziomie go\u015bcinnego systemu L2 mo\u017cna zwolni\u0107 pami\u0119\u0107 w strukturze svm->nested.msrpm, w kt\u00f3rej przechowywany jest bit MSR, mimo \u017ce nadal jest u\u017cywany, i uzyska\u0107 dost\u0119p do MSR \u015brodowiska hosta.
\n
\u0179r\u00f3d\u0142o: 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\udd47Luka w kodzie KVM specyficznym dla procesor\u00f3w AMD, umo\u017cliwiaj\u0105ca wykonanie kodu poza systemem go\u015bcia | ProHoster","description":"Badacze z zespo\u0142u Google Project Zero odkryli luk\u0119 (CVE-2021-29657) w dostarczanym z j\u0105drem Linux hypervisora KVM, kt\u00f3ra pozwala na obej\u015bcie izolacji systemu go\u015bcia i wykonanie w\u0142asnego kodu 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