Information has been published about 21 vulnerabilities in the GRUB2 bootloader, most of which lead to buffer overflows and can be used to bypass the UEFI Secure Boot verification mechanism. The issues have only been mitigated through patches for now. The status of vulnerability mitigation in distributions can be assessed on these pages: Debian, Ubuntu, SUSE, RHEL, Fedora. Simply updating the package is not enough to address the issues in GRUB2; new internal digital signatures must also be generated, and installers, boot loaders, kernel packages, fwupd firmware, and shim layers must be updated. <\/p>\n
Uppt\u00e4ckta s\u00e5rbarheter: <\/p>\n
I de flesta Linux-distributioner anv\u00e4nds ett litet lager shim, som \u00e4r certifierat med en digital signatur av Microsoft, f\u00f6r verifierad uppstart i UEFI Secure Boot-l\u00e4ge. Detta lager verifierar GRUB2 med sin egen certifikat, vilket g\u00f6r att distributionsutvecklare inte beh\u00f6ver certifiera varje k\u00e4rn- och GRUB-uppdatering hos Microsoft. S\u00e5rbarheter i GRUB2 kan utnyttjas f\u00f6r att k\u00f6ra kod efter att shim verifierats framg\u00e5ngsrikt, men innan operativsystemet startas, genom att bryta kedjan av f\u00f6rtroende under aktivt Secure Boot-l\u00e4ge och ta full kontroll \u00f6ver den fortsatta startprocessen, exempelvis f\u00f6r att starta ett annat operativsystem, modifiera operativsystemskomponenter och kringg\u00e5 Lockdown-skyddet. <\/p>\n
F\u00f6r att blockera s\u00e5rbarheten utan att \u00e5terkalla den digitala signaturen kan distributioner anv\u00e4nda mekanismen SBAT (UEFI Secure Boot Advanced Targeting), vars st\u00f6d har implementerats f\u00f6r GRUB2, shim och fwupd i de flesta popul\u00e4ra Linux-distributioner. SBAT har utvecklats i samarbete med Microsoft och inneb\u00e4r att ytterligare metadata som inkluderar information om tillverkare, produkt, komponent och version l\u00e4ggs till i exekverbara filer f\u00f6r UEFI. Dessa metadata signeras digitalt och kan separat ing\u00e5 i listor \u00f6ver till\u00e5tna eller f\u00f6rbjudna komponenter f\u00f6r UEFI Secure Boot. <\/p>\n
SBAT g\u00f6r det m\u00f6jligt att blockera anv\u00e4ndningen av digitala signaturer f\u00f6r specifika versionsnummer av komponenter utan att beh\u00f6va \u00e5terkalla nycklar f\u00f6r Secure Boot. Blockering av s\u00e5rbarheter via SBAT kr\u00e4ver inte anv\u00e4ndning av en lista \u00f6ver \u00e5terkallade UEFI-certifikat (dbx), utan sker p\u00e5 niv\u00e5 av att ers\u00e4tta den interna nyckeln f\u00f6r att skapa signaturer och uppdatera GRUB2, shim och andra bootartefakter som levereras med distributioner. Innan SBAT inf\u00f6rdes var det obligatoriskt att uppdatera listan \u00f6ver \u00e5terkallade certifikat (dbx, UEFI Revocation List) f\u00f6r att helt blockera s\u00e5rbarheten, eftersom angriparen, oavsett vilken operativsystem som anv\u00e4nds, kunde utnyttja en startbar enhet med en gammal s\u00e5rbar version av GRUB2 som var certifierad med en digital signatur. \u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u044b \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u044f \u043e 21 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 \u0437\u0430\u0433\u0440\u0443\u0437\u0447\u0438\u043a\u0435 GRUB2, \u0431\u043e\u043b\u044c\u0448\u0438\u043d\u0441\u0442\u0432\u043e \u0438\u0437 \u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u043f\u0440\u0438\u0432\u043e\u0434\u044f\u0442 \u043a \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u0431\u0443\u0444\u0435\u0440\u0430 \u0438 \u043c\u043e\u0433\u0443\u0442 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c\u0441\u044f \u0434\u043b\u044f \u043e\u0431\u0445\u043e\u0434\u0430 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u0430 \u0432\u0435\u0440\u0438\u0444\u0438\u0446\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0439 \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0438 UEFI Secure Boot. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u043f\u043e\u043a\u0430 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u044b \u0442\u043e\u043b\u044c\u043a\u043e \u0432 \u0432\u0438\u0434\u0435 \u043f\u0430\u0442\u0447\u0430. \u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0435\u0439 \u0432 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 \u043c\u043e\u0436\u043d\u043e \u043e\u0446\u0435\u043d\u0438\u0442\u044c \u043d\u0430 \u0434\u0430\u043d\u043d\u044b\u0445 \u0441\u0442\u0440\u0430\u043d\u0438\u0446\u0430\u0445: Debian, Ubuntu, SUSE, RHEL, Fedora. \u0414\u043b\u044f \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0431\u043b\u0435\u043c \u0432 GRUB2 \u043d\u0435\u0434\u043e\u0441\u0442\u0430\u0442\u043e\u0447\u043d\u043e \u043f\u0440\u043e\u0441\u0442\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-122049","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\udd4721 s\u00e5rbarheter identifierade i GRUB2-bootloadern | 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K\u00e4lla: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"