{"id":121698,"date":"2025-02-04T09:46:00","date_gmt":"2025-02-04T07:46:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-zagruzchike-mikrokoda-v-cpu-amd-pozvolyayushhaya-obojti-izolyacziyu-sev-snp"},"modified":"2025-02-04T09:46:00","modified_gmt":"2025-02-04T07:46:00","slug":"uyazvimost-v-zagruzchike-mikrokoda-v-cpu-amd-pozvolyayushhaya-obojti-izolyacziyu-sev-snp","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/news\/uyazvimost-v-zagruzchike-mikrokoda-v-cpu-amd-pozvolyayushhaya-obojti-izolyacziyu-sev-snp","title":{"rendered":"O vulnerabilitate \u00een bootloader-ul microcodului \u00een CPU AMD, care permite ocolirea izol\u0103rii SEV-SNP","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Cercet\u0103torii de securitate de la Google au publicat informa\u021bii despre o vulnerabilitate (CVE-2024-56161) \u00een procesoarele AMD, care afecteaz\u0103 \u00eenc\u0103rc\u0103torul microcodului \u0219i permite ocolirea mecanismului de verificare a semn\u0103turii digitale \u00een urma actualiz\u0103rilor de microcod. \u00cenc\u0103rcarea unui microcod modificat poate compromite mecanismul AMD SEV (Virtualizare Cryptat\u0103 Securizat\u0103), utilizat \u00een sistemele de virtualizare pentru a proteja ma\u0219inile virtuale de interven\u021bii din partea hypervisorului sau a administratorului sistemului gazd\u0103. <\/p>\n

Vulnerabilitatea este cauzat\u0103 de utilizarea unei func\u021bii hash nesigure \u00een codul care efectueaz\u0103 verificarea semn\u0103turii digitale dup\u0103 \u00eenc\u0103rcarea microcodului \u00een CPU. Pentru a efectua un atac, este necesar\u0103 ob\u021binerea de drepturi de administrator \u00een sistemul local (capacitatea de a executa cod la nivelul zero al protec\u021biei (ring0), f\u0103r\u0103 a fi \u00eentr-o ma\u0219in\u0103 virtual\u0103). <\/p>\n

\u00cen timpul atacului, se poate interveni \u00een func\u021bionarea sistemelor gazd\u0103, protejate prin extensiile AMD SEV (Virtualizare Cryptat\u0103 Securizat\u0103) \u0219i SEV-SNP (Paginare Criptat\u0103 Securizat\u0103), care ofer\u0103 garan\u021bii privind integritatea memoriei. ma\u0219ini virtuale<\/a>, izol\u00e2nd registrele procesorului \u0219i asigur\u00e2nd o func\u021bionare sigur\u0103 cu tabelele de pagini imbricate \u00een memorie. Mecanismul AMD SEV a fost creat pentru a se asigura c\u0103 personalul centrelor de date \u0219i furnizorii de cloud nu pot modifica sau analiza con\u021binutul memoriei sistemelor gazd\u0103 protejate, precum \u0219i c\u0103 nu pot distorsiona calculele. <\/p>\n

Cercet\u0103torii au preg\u0103tit un prototip de exploit, care permite \u00eenc\u0103rcarea unui microcod arbitrar \u00een CPU, f\u0103r\u0103 semn\u0103tur\u0103 digital\u0103. Pentru a demonstra pericolul vulnerabilit\u0103\u021bii, a fost propus\u0103 o actualizare a microcodului care schimb\u0103 logica instruc\u021biunii RDRAND, utilizat\u0103 ca una dintre sursele de entropie \u00een generatoarele de numere pseudo-aleatoare, utilizate \u00een procesul de generare a cheilor, \u00een timpul opera\u021biunilor criptografice \u0219i pentru generarea identificatorilor aleatori. <\/p>\n

Modificarea duce la restabilirea instruc\u021biunii RDRAND, return\u00e2nd doar num\u0103rul 4, \u00een locul unei secven\u021be aleatorii. Pentru a preveni atacurile reale asupra sistemelor de calcul confiden\u021bial, microcodul modificat reseteaz\u0103 flagul CF (carry flag), adic\u0103 marcheaz\u0103 valoarea returnat\u0103 ca fiind eronat\u0103. Detalii suplimentare \u0219i instrumente pentru generarea microcodului modificat vor fi publicate pe 5 martie, pentru a oferi utilizatorilor timp s\u0103 instaleze patch-ul pe sistemele lor. Un exemplu de atac de succes a fost demonstrat pentru servere<\/a> procesatoarele AMD EPYC 7B13 (Milan) \u0219i AMD Ryzen 9 7940HS (Phoenix). <\/p>\n

\u00cen raportul companiei AMD se men\u021bioneaz\u0103 c\u0103 vulnerabilitatea se manifest\u0103 \u00een procesoarele AMD bazate pe arhitectura microprocesorului Zen de genera\u021bie 1-4. Actualizarea microcodului care remediaz\u0103 vulnerabilitatea a fost lansat\u0103 pe 13 decembrie 2024 pentru procesoarele din seriile AMD EPYC 7001, 7002 \u0219i 7003 (Naples, Rome, Milan \u0219i Milan-X), iar pe 16 decembrie pentru procesoarele din seria AMD EPYC 9004 (Genoa, Genoa-X \u0219i Bergamo\/Siena). Pentru a elimina vulnerabilitatea pe sistemele care utilizeaz\u0103 atestarea SEV-SNP, este necesar\u0103 o actualizare suplimentar\u0103 a firmware-ului AMD SEV (furnizat\u0103 \u00eempreun\u0103 cu actualiz\u0103rile BIOS de c\u0103tre produc\u0103torii de echipamente). <\/p>\n

De asemenea, s-a raportat o alt\u0103 vulnerabilitate \u00een procesoarele AMD, care permite un atac prin canale laterale pentru extragerea informa\u021biilor despre calcule \u00een sistemele gazd\u0103 protejate prin utilizarea mecanismului AMD SEV. Problema afecteaz\u0103 procesoarele AMD EPYC de genera\u021bie 1-4 \u0219i este legat\u0103 de posibilitatea extragerii de date din cache-ul procesorului, care se acumuleaz\u0103 \u00een timpul func\u021bion\u0103rii sistemelor gazd\u0103 protejate. Metoda Prime+Probe poate fi folosit\u0103 pentru a analiza con\u021binutul cache-ului, presupun\u00e2nd umplerea cache-ului cu un set de valori etalon \u0219i determinarea modific\u0103rilor prin m\u0103surarea timpului de acces la acestea \u00een timpul reumplerii. Se observ\u0103 c\u0103 metodele propuse anterior pentru protec\u021bia \u00eempotriva atacurilor de tip Spectre pot fi utilizate pentru a bloca atacul.
\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 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0438\u0437 \u043a\u043e\u043c\u043f\u0430\u043d\u0438\u0438 Google \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b\u0438 \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044e \u043e\u0431 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 (CVE-2024-56161) \u0432 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0440\u0430\u0445 AMD, \u0437\u0430\u0442\u0440\u0430\u0433\u0438\u0432\u0430\u044e\u0449\u0435\u0439 \u0437\u0430\u0433\u0440\u0443\u0437\u0447\u0438\u043a \u043c\u0438\u043a\u0440\u043e\u043a\u043e\u0434\u0430 \u0438 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0435\u0439 \u043e\u0431\u043e\u0439\u0442\u0438 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u0446\u0438\u0444\u0440\u043e\u0432\u043e\u0439 \u043f\u043e\u0434\u043f\u0438\u0441\u0438 \u043f\u0440\u0438 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0439 \u043c\u0438\u043a\u0440\u043e\u043a\u043e\u0434\u0430. \u0417\u0430\u0433\u0440\u0443\u0437\u043a\u0430 \u043c\u043e\u0434\u0438\u0444\u0438\u0446\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0433\u043e \u043c\u0438\u043a\u0440\u043e\u043a\u043e\u0434\u0430 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u0441\u043a\u043e\u043c\u043f\u0440\u043e\u043c\u0435\u0442\u0438\u0440\u043e\u0432\u0430\u0442\u044c \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c AMD SEV (Secure Encrypted Virtualization), \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u0435\u043c\u044b\u0439 \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u0445 \u0432\u0438\u0440\u0442\u0443\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u0434\u043b\u044f \u0437\u0430\u0449\u0438\u0442\u044b \u0432\u0438\u0440\u0442\u0443\u0430\u043b\u044c\u043d\u044b\u0445 \u043c\u0430\u0448\u0438\u043d 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[…]<\/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-121698","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\udd47Vulnerabilitate \u00een \u00eenc\u0103rc\u0103torul de microcod \u00een CPU AMD, care permite ocolirea izol\u0103rii SEV-SNP | ProHoster","description":"Cercet\u0103torii \u00een securitate de la Google au publicat informa\u021bii despre vulnerabilitatea (CVE-2024-56161) \u00een procesoarele AMD, care afecteaz\u0103 \u00eenc\u0103rc\u0103torul de microcod \u0219i permite ocolirea mecanismului de verificare a semn\u0103turii 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