{"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\/ro\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","title":{"rendered":"O vulnerabilitate \u00een codul specific CPU AMD KVM, care permite executarea de cod \u00een afara sistemului oaspete.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Cercet\u0103torii din echipa Google Project Zero au identificat o vulnerabilitate (CVE-2021-29657) \u00een hipervizorul KVM furnizat cu nucleul Linux, care permite ocolirea izol\u0103rii sistemului gazd\u0103 \u0219i executarea codului propriu \u00een mediul de g\u0103zduire. Problema este prezent\u0103 \u00een codul utilizat pe sistemele cu procesoare AMD (modulul kvm-amd.ko) \u0219i nu se manifest\u0103 pentru procesoarele Intel. <\/p>\n

Cercet\u0103torii au preg\u0103tit un prototip func\u021bional de exploit care permite, dintr-un mediu de gazd\u0103, lansarea unui shell root \u00een mediul gazd\u0103 pe un sistem cu procesor AMD Epyc 7351P \u0219i kernel Linux 5.10. Se observ\u0103 c\u0103 aceasta este prima vulnerabilitate de tip «guest-to-host» \u00een hipervizorul \u00een sine. KVM<\/a>, care nu este legat\u0103 de erori \u00een componentele rulante \u00een spa\u021biul utilizatorului, precum QEMU. Corectarea a fost acceptat\u0103 \u00een nucleu la sf\u00e2r\u0219itul lunii martie. Problema apare \u00eencep\u00e2nd cu nucleul Linux 5.10-rc1 \u0219i se \u00eencheie cu v5.12-rc6, adic\u0103 acoper\u0103 doar nucleele 5.10 \u0219i 5.11 (majoritatea ramurilor stabile ale distribu\u021biilor nu sunt afectate de aceast\u0103 problem\u0103). <\/p>\n

Problema este prezent\u0103 \u00een mecanismul nested_svm_vmrun, implementat folosind extensia AMD SVM (Secure Virtual Machine) \u0219i care permite organizarea lans\u0103rii \u00een cuib a sistemelor gazd\u0103. Pentru a realiza corect aceast\u0103 func\u021bionalitate, hipervizorul trebuie s\u0103 intercepteze toate instruc\u021biunile SVM executate \u00een sistemele gazd\u0103, s\u0103 le emuleze comportamentul \u0219i s\u0103 sincronizeze starea cu hardware-ul, ceea ce este o sarcin\u0103 destul de complex\u0103. Analiz\u00e2nd implementarea propus\u0103 \u00een KVM, cercet\u0103torii au descoperit o eroare logic\u0103 care permite influen\u021barea con\u021binutului registrilor MSR (Model-Specific Register) ai gazdei din sistemul gazd\u0103, ceea ce poate fi folosit pentru a lansa cod la nivel de gazd\u0103. <\/p>\n

\u00cen special, executarea opera\u021biei VMRUN dintr-un sistem de gazd\u0103 de nivel secundar (L2, pornit dintr-un alt sistem de gazd\u0103) duce la un al doilea apel nested_svm_vmrun \u0219i la deteriorarea structurii svm->nested.hsave, pe care se suprapun date din vmcb-ul sistemului de gazd\u0103 L2. Ca urmare, apare o situa\u021bie \u00een care, la nivelul sistemului de gazd\u0103 L2, se poate elibera memoria din structura svm->nested.msrpm, \u00een care este stocat bitul MSR, chiar dac\u0103 acesta continu\u0103 s\u0103 fie utilizat, \u0219i se poate accesa MSR-ul mediului gazd\u0103.
\n
Sursa: opennet.ro<\/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\udd47 Vulnerabilitate \u00een codul KVM specific CPU-urilor AMD, care permite executarea de cod \u00een afara sistemului gazd\u0103 | ProHoster","description":"Cercet\u0103torii din echipa Google Project Zero au identificat o vulnerabilitate (CVE-2021-29657) \u00een hipervizorul KVM livrat \u00eempreun\u0103 cu kernelul Linux, care permite ocolirea izol\u0103rii sistemului gazd\u0103 \u0219i executarea de cod pe partea acestuia.","canonical_url":"https:\/\/prohoster.info\/ro\/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":"ro_RO","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 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