{"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\/es\/blog\/news\/uyazvimost-v-speczifichnom-dlya-cpu-amd-kode-kvm-pozvolyayushhaya-vypolnit-kod-vne-gostevoj-sistemy","title":{"rendered":"Vulnerabilidad en el c\u00f3digo KVM espec\u00edfico de CPU AMD que permite ejecutar c\u00f3digo fuera del sistema hu\u00e9sped","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Investigadores del equipo de Google Project Zero han identificado una vulnerabilidad (CVE-2021-29657) en el hipervisor KVM incluido en el n\u00facleo de Linux, que permite eludir la separaci\u00f3n de un sistema invitado y ejecutar c\u00f3digo en el entorno del host. El problema est\u00e1 presente en el c\u00f3digo utilizado en sistemas con procesadores AMD (m\u00f3dulo kvm-amd.ko) y no se manifiesta en procesadores Intel. <\/p>\n

Los investigadores han preparado un prototipo de trabajo de un exploit que permite iniciar un shell root en el entorno del host desde un entorno de invitado en un sistema con un procesador AMD Epyc 7351P y el n\u00facleo Linux 5.10. Se se\u00f1ala que es la primera vulnerabilidad de tipo \u00abguest-to-host\u00bb en el hipervisor mismo. KVM<\/a>, no relacionada con errores en componentes que se ejecutan en el espacio de usuario, como QEMU. La correcci\u00f3n se acept\u00f3 en el n\u00facleo a finales de marzo. El problema se manifiesta desde el n\u00facleo de Linux 5.10-rc1 hasta v5.12-rc6, es decir, abarca solo los n\u00facleos 5.10 y 5.11 (la mayor\u00eda de las ramas estables de los distribuciones no se ven afectadas por el problema). <\/p>\n

El problema est\u00e1 presente en el mecanismo nested_svm_vmrun, implementado usando la extensi\u00f3n AMD SVM (Secure Virtual Machine) que permite realizar ejecuciones anidadas de sistemas invitados. Para una correcta implementaci\u00f3n de esta funcionalidad, el hipervisor debe interceptar todas las instrucciones SVM ejecutadas en los sistemas invitados, emular su comportamiento y sincronizar el estado con el hardware, lo cual es una tarea bastante compleja. Tras analizar la implementaci\u00f3n ofrecida en KVM, los investigadores encontraron un error l\u00f3gico que permite influir en el contenido de los registros MSR (Model-Specific Register) del host desde el sistema invitado, lo que se puede usar para ejecutar c\u00f3digo a nivel del host. <\/p>\n

En particular, la ejecuci\u00f3n de la operaci\u00f3n VMRUN desde el sistema invitado de segundo nivel (L2, ejecutado desde otro sistema invitado) lleva a una segunda llamada a nested_svm_vmrun y a la corrupci\u00f3n de la estructura svm->nested.hsave, que se superpone con los datos de vmcb del sistema invitado L2. Como resultado, surge una situaci\u00f3n donde, a nivel del sistema invitado L2, se puede liberar memoria en la estructura svm->nested.msrpm, donde se almacena el bit MSR, a pesar de que sigue en uso, y obtener acceso al MSR del entorno del host.
\n
Fuente: 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\udd47Vulnerabilidad en el c\u00f3digo KVM espec\u00edfico de la CPU AMD, que permite ejecutar c\u00f3digo fuera del sistema hu\u00e9sped | ProHoster","description":"Investigadores del equipo Google Project Zero han identificado una vulnerabilidad (CVE-2021-29657) en el hipervisor KVM incluido en el n\u00facleo de Linux, que permite eludir la aislamiento del sistema hu\u00e9sped y ejecutar su propio c\u00f3digo en el lado del host.","canonical_url":"https:\/\/prohoster.info\/es\/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":"es_ES","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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