{"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\/hu\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","title":{"rendered":"Sebez\u00e9s az AMD CPU-hoz specifikus KVM k\u00f3dban, amely lehet\u0151v\u00e9 teszi a k\u00f3d v\u00e9grehajt\u00e1s\u00e1t a vend\u00e9grendszeren k\u00edv\u00fcl","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A Google Project Zero csapat\u00e1nak kutat\u00f3i egy sebez\u0151s\u00e9get (CVE-2021-29657) fedeztek fel a Linux kernelben tal\u00e1lhat\u00f3 KVM hypervisorban, amely lehet\u0151v\u00e9 teszi a vend\u00e9grendszer izol\u00e1ci\u00f3j\u00e1nak megker\u00fcl\u00e9s\u00e9t \u00e9s saj\u00e1t k\u00f3d v\u00e9grehajt\u00e1s\u00e1t a host k\u00f6rnyezet oldal\u00e1n. A probl\u00e9ma az AMD processzorokkal (kvm-amd.ko modul) haszn\u00e1lt k\u00f3d r\u00e9sz\u00e9ben tal\u00e1lhat\u00f3, \u00e9s nem jelentkezik Intel processzorok eset\u00e9n. <\/p>\n

A kutat\u00f3k elk\u00e9sz\u00edtettek egy m\u0171k\u00f6d\u0151 protot\u00edpust egy exploit sz\u00e1m\u00e1ra, amely lehet\u0151v\u00e9 teszi a root shell ind\u00edt\u00e1s\u00e1t a gazda k\u00f6rnyezetben egy AMD Epyc 7351P processzorral rendelkez\u0151 rendszeren, Linux 5.10 kernel alatt, a vend\u00e9g k\u00f6rnyezetb\u0151l. Megjegyezt\u00e9k, hogy ez az els\u0151 'guest-to-host' t\u00edpus\u00fa r\u00e9s a hipervizorban. KVM<\/a>, amely nem kapcsol\u00f3dik felhaszn\u00e1l\u00f3i t\u00e9rben v\u00e9grehajtott komponensek, p\u00e9ld\u00e1ul QEMU hib\u00e1ihoz. A jav\u00edt\u00e1st m\u00e1rcius v\u00e9g\u00e9n fogadt\u00e1k el a kernelbe. A probl\u00e9ma a Linux 5.10-rc1 kernelt\u0151l kezdve eg\u00e9szen a v5.12-rc6-ig jelentkezik, teh\u00e1t csak a 5.10 \u00e9s 5.11 kernelt \u00e9rinti (a probl\u00e9ma a legt\u00f6bb stabil disztrib\u00faci\u00f3t nem \u00e9rintette). <\/p>\n

A probl\u00e9ma a nested_svm_vmrun mechanizmusban tal\u00e1lhat\u00f3, amely az AMD SVM (Secure Virtual Machine) kiterjeszt\u00e9st haszn\u00e1lja a vend\u00e9grendszerek be\u00e1gyazott futtat\u00e1s\u00e1nak lehet\u0151v\u00e9 t\u00e9tel\u00e9re. A hypervisornak, ahhoz, hogy ezt a funkci\u00f3t helyesen val\u00f3s\u00edthassa meg, le kell \u00e1ll\u00edtania az \u00f6sszes SVM utas\u00edt\u00e1st, amelyet a vend\u00e9grendszerekben hajtanak v\u00e9gre, emul\u00e1lnia kell a viselked\u00e9s\u00fcket \u00e9s szinkroniz\u00e1lnia kell az \u00e1llapotot a hardverrel, ami meglehet\u0151sen bonyolult feladat. A kutat\u00f3k elemezve a KVM megval\u00f3s\u00edt\u00e1st logikai hib\u00e1t tal\u00e1ltak, amely lehet\u0151v\u00e9 teszi a host MSR regiszter\u00e9nek (Model-Specific Register) tartalm\u00e1nak befoly\u00e1sol\u00e1s\u00e1t a vend\u00e9grendszerb\u0151l, amit fel lehet haszn\u00e1lni a host szint\u0171 k\u00f3d v\u00e9grehajt\u00e1s\u00e1ra. <\/p>\n

K\u00fcl\u00f6n\u00f6sen a VMRUN m\u0171velet v\u00e9grehajt\u00e1sa egy m\u00e1sodik szint\u0171 vend\u00e9g rendszerb\u0151l (L2, amely egy m\u00e1sik vend\u00e9g rendszerb\u0151l fut) a nested_svm_vmrun m\u00e1sodik h\u00edv\u00e1s\u00e1hoz \u00e9s az svm->nested.hsave strukt\u00fara s\u00e9r\u00fcl\u00e9s\u00e9hez vezet, amelyre az L2 vend\u00e9g rendszer vmcb-j\u00e9b\u0151l sz\u00e1rmaz\u00f3 adatok ker\u00fclnek. Ennek eredm\u00e9nyek\u00e9ppen a L2 vend\u00e9g rendszer szintj\u00e9n lehet\u0151v\u00e9 v\u00e1lik a mem\u00f3ria felszabad\u00edt\u00e1sa az svm->nested.msrpm strukt\u00far\u00e1ban, ahol az MSR bit tal\u00e1lhat\u00f3, noha az tov\u00e1bbra is haszn\u00e1latban van, \u00edgy hozz\u00e1f\u00e9r\u00e9st nyer\u00fcnk a gazda k\u00f6rnyezet MSR-hez.
\n
Forr\u00e1s: 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\udd47A KVM AMD CPU-specifikus k\u00f3dj\u00e1ban l\u00e9v\u0151 biztons\u00e1gi r\u00e9s, amely lehet\u0151v\u00e9 teszi a k\u00f3d v\u00e9grehajt\u00e1s\u00e1t a vend\u00e9g rendszeren k\u00edv\u00fcl | ProHoster","description":"A Google Project Zero csapat\u00e1nak kutat\u00f3i felfedezt\u00e9k a KVM hypervisorban tal\u00e1lhat\u00f3 (CVE-2021-29657) egy biztons\u00e1gi hi\u00e1nyoss\u00e1got, amely lehet\u0151v\u00e9 teszi a vend\u00e9g rendszer elszigetel\u00e9s\u00e9nek megker\u00fcl\u00e9s\u00e9t \u00e9s k\u00f3d v\u00e9grehajt\u00e1s\u00e1t az oldalon.","canonical_url":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"hu_HU","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 \u0441\u043f\u0435\u0446\u0438\u0444\u0438\u0447\u043d\u043e\u043c \u0434\u043b\u044f CPU AMD \u043a\u043e\u0434\u0435 KVM, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043a\u043e\u0434 \u0432\u043d\u0435 \u0433\u043e\u0441\u0442\u0435\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b | ProHoster","og:description":"\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 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