{"id":105601,"date":"2022-11-16T21:37:02","date_gmt":"2022-11-16T19:37:02","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot"},"modified":"2022-11-16T21:37:02","modified_gmt":"2022-11-16T19:37:02","slug":"dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","status":"publish","type":"post","link":"https:\/\/prohoster.info\/nl\/blog\/news\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","title":{"rendered":"Twee kwetsbaarheden in GRUB2 waarmee UEFI Secure Boot-beveiliging kan worden omzeild","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Details have been revealed about two vulnerabilities in the GRUB2 bootloader that could lead to code execution when using specially crafted fonts and processing certain Unicode sequences. The vulnerabilities can be exploited to bypass the UEFI Secure Boot verified boot mechanism.        <\/p>\n<p>Ge\u00efdentificeerde kwetsbaarheden:  <\/p>\n<ul>\n<li class=\"l\"> CVE-2022-2601 \u2014 buffer overflow in the function grub_font_construct_glyph() when processing specially formatted fonts in pf2 format, occurring due to incorrect calculation of the max_glyph_size parameter and allocation of a memory area that is intentionally smaller than needed to accommodate the glyphs.\n<li class=\"l\"> CVE-2022-3775 \u2014 out-of-bounds write of allocated memory when rendering certain Unicode sequences with a specially formatted font. The issue exists in the font processing code and is caused by a lack of proper checks to match the glyph's width and height to the size of the available bitmap. An attacker can craft input in such a way that it causes the tail of data to be written beyond the allocated buffer. It is noted that, despite the complexity of exploiting the vulnerability, achieving code execution cannot be ruled out.                <\/ul>\n<p> A fix has been published in the form of a patch. The status of vulnerability remediation in various distributions can be assessed on the following pages: Ubuntu, SUSE, RHEL, Fedora, Debian. Simply updating the package is not sufficient to address the issues in GRUB2; it will also be necessary to generate new internal digital signatures and update the installers, bootloaders, kernel packages, fwupd firmware, and the shim layer.       <\/p>\n<p>In most Linux distributions, a small shim layer, certified by a digital signature from Microsoft, is used for verified boot in UEFI Secure Boot mode. This layer verifies GRUB2 with its own certificate, allowing distribution developers not to certify every kernel and GRUB update with Microsoft. Vulnerabilities in GRUB2 allow achieving code execution at the point after successful verification of the shim but before the operating system is loaded, inserting into the trust chain during active Secure Boot mode and gaining full control over the further boot process, including booting another OS, modifying operating system components, and bypassing Lockdown protection.     <\/p>\n<p>Om de kwetsbaarheid te blokkeren zonder de digitale handtekening in te trekken, kunnen distributies het SBAT-mechanisme (UEFI Secure Boot Advanced Targeting) gebruiken, dat wordt ondersteund voor GRUB2, shim en fwupd in de meeste populaire Linux-distributies. SBAT is in samenwerking met Microsoft ontwikkeld en houdt in dat aanvullende metadata, die informatie bevat over de fabrikant, het product, de component en de versie, worden toegevoegd aan de uitvoerbare bestanden van UEFI-componenten. Deze metadata worden digitaal ondertekend en kunnen afzonderlijk worden opgenomen in lijsten van goedgekeurde of geblokkeerde componenten voor UEFI Secure Boot.      <\/p>\n<p>SBAT maakt het mogelijk om het gebruik van digitale handtekeningen voor specifieke versienummers van componenten te blokkeren zonder sleutelintrekking voor Secure Boot. Het blokkeren van kwetsbaarheden via SBAT vereist geen gebruik van de lijst met ingetrokken UEFI-certificaten (dbx), maar vindt plaats op het niveau van het vervangen van de interne sleutel voor het genereren van handtekeningen en het updaten van GRUB2, shim en andere opstartartefacten geleverd door de distributies. Voor de implementatie van SBAT was het bijwerken van de lijst met ingetrokken certificaten (dbx, UEFI Revocation List) een verplicht voorwaarde voor volledige blokkering van de kwetsbaarheid, omdat een aanvaller, ongeacht het gebruikte besturingssysteem, een opstartmedium met een oude kwetsbare versie van GRUB2, ondertekend met digitale handtekening, kon gebruiken om UEFI Secure Boot te compromitteren.<br \/>\n<br \/>Bron: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=58130\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0420\u0430\u0441\u043a\u0440\u044b\u0442\u044b \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u044f \u043e \u0434\u0432\u0443\u0445 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044f\u0445 \u0432 \u0437\u0430\u0433\u0440\u0443\u0437\u0447\u0438\u043a\u0435 GRUB2, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u043c\u043e\u0433\u0443\u0442 \u043f\u0440\u0438\u0432\u0435\u0441\u0442\u0438 \u043a \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u043a\u043e\u0434\u0430 \u043f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0445 \u0448\u0440\u0438\u0444\u0442\u043e\u0432 \u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0451\u043d\u043d\u044b\u0445 Unicode-\u043f\u043e\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c\u043d\u043e\u0441\u0442\u0435\u0439. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\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. \u0412\u044b\u044f\u0432\u043b\u0435\u043d\u043d\u044b\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438: CVE-2022-2601 &#8212; \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0431\u0443\u0444\u0435\u0440\u0430 \u0432 \u0444\u0443\u043d\u043a\u0446\u0438\u0438 grub_font_construct_glyph() \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0445 \u0448\u0440\u0438\u0444\u0442\u043e\u0432 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0435 pf2, \u0432\u043e\u0437\u043d\u0438\u043a\u0430\u044e\u0449\u0435\u0435 \u0438\u0437-\u0437\u0430 \u043d\u0435\u0432\u0435\u0440\u043d\u043e\u0433\u043e \u0440\u0430\u0441\u0447\u0451\u0442\u0430 [&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-105601","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.4 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u0420\u0430\u0441\u043a\u0440\u044b\u0442\u044b \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u044f \u043e \u0434\u0432\u0443\u0445 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044f\u0445 \u0432 \u0437\u0430\u0433\u0440\u0443\u0437\u0447\u0438\u043a\u0435 GRUB2, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u043c\u043e\u0433\u0443\u0442 \u043f\u0440\u0438\u0432\u0435\u0441\u0442\u0438 \u043a \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u043a\u043e\u0434\u0430 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code-uitvoering bij het gebruik van speciaal opgemaakte lettertypen en het verwerken van bepaalde Unicode-sequenties.","canonical_url":"https:\/\/prohoster.info\/nl\/blog\/news\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"nl_NL","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\u0414\u0432\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 GRUB2, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0435 \u043e\u0431\u043e\u0439\u0442\u0438 \u0437\u0430\u0449\u0438\u0442\u0443 UEFI Secure 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