{"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\/hr\/blog\/news\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","title":{"rendered":"Dva ranjivosti u GRUB2, koja omogu\u0107uju zaobila\u017eenje za\u0161tite UEFI Secure Boot","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Otkrivene su informacije o dvije ranjivosti u GRUB2 bootloaderu koje mogu omogu\u0107iti izvr\u0161avanje koda koriste\u0107i posebno oblikovane fontove i obradu odre\u0111enih Unicode sekvenci. Ranjivosti se mogu iskoristiti za zaobila\u017eenje mehanizma verifikovane UEFI Secure Boot.        <\/p>\n<p>Otkrivene ranjivosti:  <\/p>\n<ul>\n<li class=\"l\"> CVE-2022-2601 \u2014 prelivanje bafera u funkciji grub_font_construct_glyph() prilikom obrade posebno oblikovanih fontova u pf2 formatu, \u0161to proizlazi iz pogre\u0161nog izra\u010duna parametra max_glyph_size i alokacije memorijskog prostora koji je unaprijed manji nego \u0161to je potrebno za smje\u0161taj glifa.\n<li class=\"l\"> CVE-2022-3775 \u2014 zapis izvan dodijeljene memorijske povr\u0161ine prilikom renderiranja nekih Unicode sekvenci pomo\u0107u posebno oblikovanog fonta. Problem se pojavljuje u kodu za obradu fontova i uzrokovan je nedostatkom adekvatnih provjera uskla\u0111enosti \u0161irine i visine glifa s veli\u010dinom dostupne bitmap slike. Napada\u010d mo\u017ee oblikovati unos na na\u010din da izazove zapis podataka na rubu dodijeljenog bafera. Napominje se da, unato\u010d slo\u017eenosti iskori\u0161tavanja ranjivosti, nije isklju\u010dena mogu\u0107nost da do\u0111e do izvr\u0161avanja koda.                <\/ul>\n<p> Ispravka je objavljena u obliku zakrpe. Status ispravke ranjivosti u distribucijama mo\u017ee se proceniti na ovim stranicama: Ubuntu, SUSE, RHEL, Fedora, Debian. Da bi se problemi u GRUB2 re\u0161ili, nije dovoljno samo a\u017eurirati paket, potrebno je tako\u0111e formirati nove unutra\u0161nje digitalne potpise i a\u017eurirati instalacione programe, bootloadere, pakete s kernelom, fwupd firmware i shim sloj.       <\/p>\n<p>U ve\u0107ini Linux distribucija za verifikovano podizanje sistema u re\u017eimu UEFI Secure Boot koristi se mali shim sloj, digitalno potpisan od strane Microsoft-a. Ovaj sloj verifikuje GRUB2 vlastitim sertifikatom, \u0161to omogu\u0107ava developerima distribucija da ne potpisuju svaku nadogradnju kernela i GRUB-a u Microsoft-u. Ranjivosti u GRUB2 omogu\u0107avaju izvr\u0161avanje vlastitog koda u fazi nakon uspe\u0161ne verifikacije shima, ali pre pokretanja operativnog sistema, upadaju\u0107i u lanac poverenja dok je aktivan re\u017eim Secure Boot i sti\u010du\u0107i potpunu kontrolu nad daljim procesom podizanja sustava, uklju\u010duju\u0107i pokretanje druge OS, modifikaciju komponenti operativnog sistema i zaobila\u017eenje Lockdown za\u0161tite.     <\/p>\n<p>Za blokiranje ranjivosti bez opoziva digitalne potpise, distribucije mogu koristiti mehanizam SBAT (UEFI Secure Boot Advanced Targeting), \u010dija podr\u0161ka je implementirana za GRUB2, shim i fwupd u ve\u0107ini popularnih Linux distribucija. SBAT je razvijen u saradnji s Microsoftom i podrazumeva dodavanje dodatnih metapodataka u izvr\u0161ne datoteke UEFI komponenti, koji uklju\u010duju informacije o proizvo\u0111a\u010du, proizvodu, komponenti i verziji. Ovi metapodaci su potpisani digitalnom potpisom i mogu biti odvojeno uklju\u010deni u liste dozvoljenih ili zabranjenih komponenti za UEFI Secure Boot.      <\/p>\n<p>SBAT omogu\u0107ava blokiranje kori\u0161\u0107enja digitalne potpise za pojedina\u010dne verzije komponenti bez potrebe za opozivom klju\u010deva za Secure Boot. Blokiranje ranjivosti putem SBAT-a ne zahteva kori\u0161\u0107enje liste opozvanih UEFI sertifikata (dbx), ve\u0107 se vr\u0161i na nivou zamene internog klju\u010da za formiranje potpisa i nadogradnju GRUB2, shima i drugih boot artefakata obezbe\u0111enih od strane distribucija. Pre implementacije SBAT-a, a\u017euriranje liste opozvanih sertifikata (dbx, UEFI Revocation List) bilo je obavezno za potpuno blokiranje ranjivosti, jer je napada\u010d, bez obzira na kori\u0161\u0107enje operativnog sistema, mogao da iskoristi boot medij sa starom ranjivom verzijom GRUB2, potpisanom digitalnim potpisom.<br \/>\n<br \/>Izvor: <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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dovesti do izvr\u0161enja koda prilikom kori\u0161tenja posebno oblikovanih fontova i obrade odre\u0111enih Unicode sekvenci.","canonical_url":"https:\/\/prohoster.info\/hr\/blog\/news\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"hr_HR","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 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