{"id":149133,"date":"2025-11-21T17:11:55","date_gmt":"2025-11-21T15:11:55","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/6-uyazvimostej-v-zagruzchike-grub2-pozvolyayushhih-obojti-uefi-secure-boot"},"modified":"2025-11-21T17:11:55","modified_gmt":"2025-11-21T15:11:55","slug":"6-uyazvimostej-v-zagruzchike-grub2-pozvolyayushhih-obojti-uefi-secure-boot","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/6-uyazvimostej-v-zagruzchike-grub2-pozvolyayushhih-obojti-uefi-secure-boot","title":{"rendered":"6 s\u00e5rbarheder i GRUB2-bootloaderen, der muligg\u00f8r omg\u00e5else af UEFI Secure Boot","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Der er offentliggjort et s\u00e6t patches, der adresserer 6 s\u00e5rbarheder i GRUB2 bootloaderen, hvoraf de fleste kan f\u00f8re til use-after-free problemer. Potentielt opdagede problemer kan udnyttes til at omg\u00e5 UEFI Secure Boot's verificeringsmekanisme. Status for s\u00e5rbarhedslukning i distributionerne kan vurderes p\u00e5 f\u00f8lgende sider: Debian, Ubuntu, SUSE, RHEL, Arch og Fedora. For at l\u00f8se problemerne i GRUB2 er det ikke nok blot at opdatere pakken; det er ogs\u00e5 n\u00f8dvendigt at oprette nye interne digitale signaturer og opdatere installat\u00f8rer, bootloadere, kernepakker, fwupd-firmware og shim-laget.         <\/p>\n<p>Identificerede s\u00e5rbarheder:  <\/p>\n<ul>\n<li class=\"l\"> CVE-2025-61661 \u2014 buffer overflow in the function grub_usb_get_string(), which can be exploited when processing strings in UTF-8 and UTF-16 encoding transmitted during USB device connection. The issue arises because the buffer is allocated based on the string size indicated in the first message from the USB device, while the size during encoding conversion is calculated based on subsequent read operations from the USB device. Consequently, an attacker can use a modified USB device that initially returns a reduced size value.\n<li class=\"l\"> CVE-2025-61663, CVE-2025-61664, CVE-2025-54770, CVE-2025-61662 \u2014 lack of cleanup of the command handlers 'normal', 'normal_exit', 'net_set_vlan', and 'gettext' when unloading the 'normal', 'net', and 'gettext' modules, creating conditions for accessing memory after it has been freed (use-after-free) if the noted commands are executed after unloading the respective modules. Similar vulnerabilities have also been found for the commands 'functional_test' and 'all_functional_test', but they have not been assigned CVE identifiers as these commands are part of the testing library and should not be included in production builds.\n<li class=\"l\"> CVE-2025-54771 \u2014 error in reference counting for 'fs' structures in the function grub_file_close(), leading to accessing memory after it has been freed (use-after-free).        <\/ul>\n<p>I de fleste Linux-distributioner bruges et lille lag shim, som er digitalt signeret af Microsoft, til verifikation af opstart i UEFI Secure Boot-tilstand. Dette lag verificerer GRUB2 med sin egen certifikat, hvilket giver distribut\u00f8rerne mulighed for ikke at skulle godkende hver opdatering af kerne og GRUB hos Microsoft. S\u00e5rbarheder i GRUB2 g\u00f8r det muligt at udf\u00f8re sin egen kode efter en vellykket verifikation af shim, men f\u00f8r operativsystemet er indl\u00e6st, ved at tr\u00e6nge ind i tillidsk\u00e6den under aktiv Secure Boot-tilstand og f\u00e5 fuld kontrol over den videre opstartsproces, for eksempel til at indl\u00e6se et andet OS, modificere komponenter i operativsystemet og omg\u00e5 Lockdown-beskyttelsen.     <\/p>\n<p>For at blokere s\u00e5rbarheden uden at tilbagekalde den digitale signatur kan distributionerne anvende mekanismen SBAT (UEFI Secure Boot Advanced Targeting), som underst\u00f8ttes af GRUB2, shim og fwupd i de fleste popul\u00e6re Linux-distributioner. SBAT er udviklet i samarbejde med Microsoft og indeb\u00e6rer tilf\u00f8jelse af metadata til UEFI-komponenternes eksekverbare filer, som inkluderer oplysninger om producent, produkt, komponent og version. De n\u00e6vnte metadata signeres digitalt og kan separat inkluderes i lister over tilladte eller forbudte komponenter til UEFI Secure Boot.      <\/p>\n<p>SBAT g\u00f8r det muligt at blokere brugen af den digitale signatur for specifikke versionsnumre af komponenter uden at skulle tilbagekalde n\u00f8glerne til Secure Boot. Blokering af s\u00e5rbarheder gennem SBAT kr\u00e6ver ikke brugen af en liste over tilbagekaldte UEFI-certifikater (dbx), men udf\u00f8res p\u00e5 niveauet for udskiftning af den interne n\u00f8gle til dannelse af signaturer og opdatering af GRUB2, shim og andre boot-artifakter, der leveres af distributionerne. Inden SBAT blev indf\u00f8rt, var opdatering af listen over tilbagekaldte certifikater (dbx, UEFI Revocation List) en obligatorisk betingelse for fuld blokering af s\u00e5rbarheden, da en angriber, uanset hvilken operativsystem der blev brugt, kunne bruge en bootbare enhed med en gammel, s\u00e5rbar version af GRUB2, signeret med et digitalt certifikat, til at kompromittere UEFI Secure Boot.<br \/>\n<br \/>Kilde: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=64298\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d \u043d\u0430\u0431\u043e\u0440 \u043f\u0430\u0442\u0447\u0435\u0439 \u0441 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0435\u043c 6 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0435\u0439 \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\u0438\u0442 \u043a \u043e\u0431\u0440\u0430\u0449\u0435\u043d\u0438\u044e \u043a \u043f\u0430\u043c\u044f\u0442\u0438 \u043f\u043e\u0441\u043b\u0435 \u0435\u0451 \u043e\u0441\u0432\u043e\u0431\u043e\u0436\u0434\u0435\u043d\u0438\u044f (use-after-free). \u041f\u043e\u0442\u0435\u043d\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u043d\u044b\u0435 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \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. \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, Arch \u0438 Fedora. \u0414\u043b\u044f \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0431\u043b\u0435\u043c [&hellip;]<\/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-149133","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d \u043d\u0430\u0431\u043e\u0440 \u043f\u0430\u0442\u0447\u0435\u0439 \u0441 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0435\u043c 6 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0435\u0439 \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 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