{"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\/sk\/blog\/news\/uyazvimost-v-zagruzchike-mikrokoda-v-cpu-amd-pozvolyayushhaya-obojti-izolyacziyu-sev-snp","title":{"rendered":"Zranite\u013enos\u0165 v bootloaderi mikrok\u00f3du v CPU AMD, umo\u017e\u0148uj\u00faca ob\u00eds\u0165 izol\u00e1ciu SEV-SNP","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Bezpe\u010dnostn\u00ed v\u00fdzkumn\u00edci z firmy Google zve\u0159ejnili informace o zranitelnosti (CVE-2024-56161) v procesorech AMD, kter\u00e1 se t\u00fdk\u00e1 zav\u00e1d\u011bc\u00edho programu mikrok\u00f3du a umo\u017e\u0148uje obej\u00edt mechanismus kontroly digit\u00e1ln\u00edho podpisu p\u0159i aktualizac\u00edch mikrok\u00f3du. Na\u010dten\u00ed modifikovan\u00e9ho mikrok\u00f3du umo\u017e\u0148uje ohrozit mechanismus AMD SEV (Secure Encrypted Virtualization), kter\u00fd se pou\u017e\u00edv\u00e1 ve virtualiza\u010dn\u00edch syst\u00e9mech k ochran\u011b virtu\u00e1ln\u00edch stroj\u016f p\u0159ed z\u00e1sahem hypervisoru nebo administr\u00e1tora hostitelsk\u00e9ho syst\u00e9mu. <\/p>\n

Zranitelnost je zp\u016fsobena pou\u017eit\u00edm nebezpe\u010dn\u00e9 hashovac\u00ed funkce v k\u00f3du, kter\u00fd prov\u00e1d\u00ed kontrolu digit\u00e1ln\u00edho podpisu po na\u010dten\u00ed mikrok\u00f3du do CPU. K proveden\u00ed \u00fatoku je nutn\u00e9 m\u00edt admin pr\u00e1va v m\u00edstn\u00edm syst\u00e9mu (mo\u017enost spustit k\u00f3d na \u00farovni nult\u00e9ho ochrann\u00e9ho okruhu (ring0), p\u0159i\u010dem\u017e se nenach\u00e1z\u00edte ve virtu\u00e1ln\u00edm stroji). <\/p>\n

B\u011bhem \u00fatoku je mo\u017en\u00e9 zas\u00e1hnout do fungov\u00e1n\u00ed hostovan\u00fdch syst\u00e9m\u016f, kter\u00e9 jsou chr\u00e1n\u011bny pomoc\u00ed roz\u0161\u00ed\u0159en\u00ed AMD SEV (Secure Encrypted Virtualization) a SEV-SNP (Secure Nested Paging), je\u017e poskytuj\u00ed z\u00e1ruky integrity pam\u011bti. virtu\u00e1ln\u00edch stroj\u016f<\/a>, izoluj\u00edc\u00ed procesorov\u00e9 registry a zaji\u0161\u0165uj\u00edc\u00ed bezpe\u010dnou pr\u00e1ci s vlo\u017een\u00fdmi tabulkami str\u00e1nek pam\u011bti. Mechanismus AMD SEV byl navr\u017een tak, aby person\u00e1l datov\u00fdch center a cloudov\u00fdch poskytovatel\u016f nemohl zm\u011bnit nebo analyzovat obsah pam\u011bti chr\u00e1n\u011bn\u00fdch hostovan\u00fdch syst\u00e9m\u016f, ani zkreslit v\u00fdpo\u010dty. <\/p>\n

V\u00fdzkumn\u00edci p\u0159ipravili prototyp exploit, kter\u00fd umo\u017e\u0148uje na\u010d\u00edst libovoln\u00fd mikrok\u00f3d do CPU, kter\u00fd nen\u00ed podepsan\u00fd digit\u00e1ln\u00edm podpisem. K demonstraci nebezpe\u010dnosti zranitelnosti bylo navr\u017eeno aktualizace mikrok\u00f3du, kter\u00e1 m\u011bn\u00ed logiku fungov\u00e1n\u00ed instrukce RDRAND, pou\u017e\u00edvan\u00e9 jako jeden ze zdroj\u016f entropie v gener\u00e1torech pseudon\u00e1hodn\u00fdch \u010d\u00edsel, je\u017e se pou\u017e\u00edvaj\u00ed p\u0159i formov\u00e1n\u00ed kl\u00ed\u010d\u016f, p\u0159i prov\u00e1d\u011bn\u00ed kryptografick\u00fdch operac\u00ed a pro generov\u00e1n\u00ed n\u00e1hodn\u00fdch identifik\u00e1tor\u016f. <\/p>\n

Zmena vedie k vr\u00e1teniu in\u0161trukcie RDRAND len \u010d\u00edsla 4, namiesto n\u00e1hodnej sekvencie. Na zabr\u00e1nenie re\u00e1lnym \u00fatokom na syst\u00e9my d\u00f4vern\u00e9ho v\u00fdpo\u010dtu upraven\u00fd mikrok\u00f3d nulovuje vlajku CF (carry flag), teda ozna\u010duje vydan\u00fa hodnotu za neplatn\u00fa. \u010eal\u0161ie detaily a n\u00e1stroje na generovanie upraven\u00e9ho mikrok\u00f3du pl\u00e1nuj\u00fa zverejni\u0165 5. marca, aby dali pou\u017e\u00edvate\u013eom \u010das nain\u0161talova\u0165 t\u00fato opravu na svojich syst\u00e9moch. \u00daspe\u0161n\u00fd pr\u00edklad \u00fatoku bol demon\u0161trovan\u00fd pre serverov<\/a> procesory AMD EPYC 7B13 (Milan) a AMD Ryzen 9 7940HS (Phoenix). <\/p>\n

V spr\u00e1ve spolo\u010dnosti AMD sa uv\u00e1dza, \u017ee zranite\u013enos\u0165 sa prejavuje v procesoroch AMD na b\u00e1ze 1-4 gener\u00e1ci\u00ed mikroarchitekt\u00fary Zen. Aktualiz\u00e1cia mikrok\u00f3du na odstr\u00e1nenie zranite\u013enosti bola vydan\u00e1 13. decembra 2024 pre procesory s\u00e9ri\u00ed AMD EPYC 7001, 7002 a 7003 (Naples, Rome, Milan a Milan-X), a 16. decembra pre procesory s\u00e9rie AMD EPYC 9004 (Genoa, Genoa-X a Bergamo\/Siena). Na odstr\u00e1nenie zranite\u013enosti v syst\u00e9moch, ktor\u00e9 pou\u017e\u00edvaj\u00fa attest\u00e1ciu SEV-SNP, je navy\u0161e potrebn\u00e1 aktualiz\u00e1cia firmv\u00e9ru AMD SEV (dod\u00e1va sa spolu s aktualiz\u00e1ciami BIOS od v\u00fdrobcov zariaden\u00ed). <\/p>\n

\u010ealej sa uv\u00e1dza o \u010fal\u0161ej zranite\u013enosti v procesoroch AMD, ktor\u00e1 umo\u017e\u0148uje vykon\u00e1vanie \u00fatoku cez ved\u013eaj\u0161ie kan\u00e1ly na extrakciu inform\u00e1ci\u00ed o v\u00fdpo\u010dtoch v hostite\u013esk\u00fdch syst\u00e9moch, chr\u00e1nen\u00fdch pomocou mechanizmu AMD SEV. Probl\u00e9m sa t\u00fdka 1-4 gener\u00e1cie procesorov AMD EPYC a s\u00favis\u00ed s mo\u017enos\u0165ou extrakcie z procesorovej cache \u00fadajov, ktor\u00e9 sa us\u00e1dzaj\u00fa po\u010das pr\u00e1ce chr\u00e1nen\u00fdch hostite\u013esk\u00fdch syst\u00e9mov. Na anal\u00fdzu obsahu cache sa m\u00f4\u017ee pou\u017ei\u0165 met\u00f3da Prime+Probe, ktor\u00e1 spo\u010d\u00edva vo vyplnen\u00ed cache referen\u010dn\u00fdm s\u00faborom hodn\u00f4t a ur\u010den\u00ed zmien cez meranie \u010dasu pr\u00edstupu k nim pri op\u00e4tovnom vyplnen\u00ed. Uv\u00e1dza sa, \u017ee na blokovanie \u00fatoku s\u00fa vhodn\u00e9 met\u00f3dy, ktor\u00e9 boli predt\u00fdm navrhnut\u00e9 na ochranu proti \u00fatokom triedy Spectre.
\n
Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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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\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\udd47Zranite\u013enos\u0165 v bootloaderi mikrok\u00f3du v CPU AMD, umo\u017e\u0148uj\u00faca ob\u00eds\u0165 izol\u00e1ciu SEV-SNP | ProHoster","description":"Bezpe\u010dnostn\u00ed v\u00fdskumn\u00edci zo spolo\u010dnosti Google zverejnili inform\u00e1cie o zranite\u013enosti (CVE-2024-56161) v procesoroch AMD, ktor\u00e1 sa t\u00fdka bootloaderu mikrok\u00f3du a umo\u017e\u0148uje ob\u00eds\u0165 mechanizmus overovania 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