{"id":107498,"date":"2023-03-24T12:48:20","date_gmt":"2023-03-24T10:48:20","guid":{"rendered":"https:\/\/prohoster.info\/?p=107498"},"modified":"2023-03-24T20:21:30","modified_gmt":"2023-03-24T18:21:30","slug":"uyazvimost-v-overlayfs-pozvolyayushhaya-povysit-svoi-privilegii","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-overlayfs-pozvolyayushhaya-povysit-svoi-privilegii","title":{"rendered":"Zranitelnost v OverlayFS, kter\u00e1 umo\u017e\u0148uje zv\u00fd\u0161it sv\u00e1 opr\u00e1vn\u011bn\u00ed","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>V j\u00e1d\u0159e Linuxu v implementaci souborov\u00e9ho syst\u00e9mu OverlayFS byla zji\u0161t\u011bna zranitelnost (CVE-2023-0386), kterou lze vyu\u017e\u00edt k z\u00edsk\u00e1n\u00ed root p\u0159\u00edstupu na syst\u00e9mech, kde je nainstalov\u00e1na podsyst\u00e9m FUSE a je povoleno montov\u00e1n\u00ed odd\u00edl\u016f OverlayFS neprivilegovan\u00fdm u\u017eivatel\u016fm (od j\u00e1dra Linux 5.11 s povolen\u00edm neprivilegovan\u00fdch u\u017eivatelsk\u00fdch jmen). Probl\u00e9m byl vy\u0159e\u0161en ve v\u011btvi j\u00e1dra 6.2. Publikaci aktualizac\u00ed bal\u00edk\u016f v distribuc\u00edch lze sledovat na str\u00e1nk\u00e1ch: Debian, Ubuntu, Gentoo, RHEL, SUSE, Fedora, Arch.           <\/p>\n<p>\u00datok prob\u00edh\u00e1 kop\u00edrov\u00e1n\u00edm soubor\u016f s p\u0159\u00edznaky setgid\/setuid z odd\u00edlu p\u0159ipojen\u00e9ho v re\u017eimu nosuid do vrstvy OverlayFS, kter\u00e1 m\u00e1 vrstvu spojenou s odd\u00edlem, jen\u017e povoluje prov\u00e1d\u011bn\u00ed soubor\u016f s p\u0159\u00edstupov\u00fdmi pr\u00e1vy suid. Zranitelnost je podobn\u00e1 probl\u00e9mu CVE-2021-3847 odhalen\u00e9mu v roce 2021, ale m\u00e1 ni\u017e\u0161\u00ed po\u017eadavky na exploitaci \u2014 ve star\u00e9m probl\u00e9mu bylo nutn\u00e9 manipulovat s xattrs, co\u017e je omezeno p\u0159i pou\u017e\u00edv\u00e1n\u00ed prostor\u016f u\u017eivatelsk\u00fdch identifik\u00e1tor\u016f (user namespace), zat\u00edmco v nov\u00e9m probl\u00e9mu se pou\u017e\u00edvaj\u00ed bity setgid\/setuid, kter\u00e9 ve user namespace nejsou zpracov\u00e1v\u00e1ny.    <\/p>\n<p>Algoritmus prov\u00e1d\u011bn\u00ed \u00fatoku:  <\/p>\n<ul>\n<li class=\"l\"> Pomoc\u00ed subsyst\u00e9mu FUSE se p\u0159ipojuje souborov\u00fd syst\u00e9m, kter\u00fd obsahuje spustiteln\u00fd soubor pat\u0159\u00edc\u00ed u\u017eivateli root s p\u0159\u00edznaky setuid\/setgid, p\u0159\u00edstupn\u00fd v\u0161em u\u017eivatel\u016fm pro z\u00e1pis. P\u0159i p\u0159ipojov\u00e1n\u00ed FUSE nastavuje re\u017eim \u201enosuid\u201c.\n<li class=\"l\"> Zru\u0161\u00ed se (unshare) prostory jmen u\u017eivatel\u016f a bod\u016f montov\u00e1n\u00ed (user\/mount namespace).\n<li class=\"l\"> P\u0159ipojuje se OverlayFS se specifikac\u00ed d\u0159\u00edve vytvo\u0159en\u00e9ho syst\u00e9mov\u00e9ho souboru v r\u00e1mci FUSE jako doln\u00ed vrstvy a horn\u00ed vrstvy zalo\u017een\u00e9 na adres\u00e1\u0159i umo\u017e\u0148uj\u00edc\u00edm z\u00e1pis. Horn\u00ed vrstva mus\u00ed b\u00fdt um\u00edst\u011bna v syst\u00e9mu soubor\u016f, p\u0159i p\u0159ipojov\u00e1n\u00ed kter\u00e9ho se nepou\u017e\u00edv\u00e1 p\u0159\u00edznak \u201enosuid\u201c.\n<li class=\"l\"> Pro soubor suid v odd\u00edle FUSE se pomoc\u00ed utility touch zm\u011bn\u00ed \u010das modifikace, co\u017e vede k jeho zkop\u00edrov\u00e1n\u00ed do horn\u00ed vrstvy OverlayFS.\n<li class=\"l\"> P\u0159i kop\u00edrov\u00e1n\u00ed j\u00e1dro nep\u0159 removes flagy setgid\/setuid, co\u017e zp\u016fsobuje, \u017ee soubor se objev\u00ed v odd\u00edlu, kter\u00fd umo\u017e\u0148uje zpracov\u00e1n\u00ed setgid\/setuid.\n<li class=\"l\"> Pro z\u00edsk\u00e1n\u00ed pr\u00e1v root sta\u010d\u00ed spustit soubor s flagy setgid\/setuid z adres\u00e1\u0159e p\u0159ipojen\u00e9ho k horn\u00ed vrstv\u011b OverlayFS.  <\/ul>\n<p>D\u00e1le lze poznamenat, \u017ee v\u00fdzkumn\u00edci z t\u00fdmu Google Project Zero zve\u0159ejnili informace o t\u0159ech zranitelnostech, kter\u00e9 byly opraveny v hlavn\u00ed v\u011btvi j\u00e1dra Linux 5.15, ale nebyly p\u0159eneseny do bal\u00ed\u010dk\u016f s j\u00e1drem z RHEL 8.x\/9.x a CentOS Stream 9.  <\/p>\n<ul>\n<li class=\"l\"> CVE-2023-1252 \u2014 p\u0159\u00edstup k ji\u017e uvoln\u011bn\u00e9 oblasti pam\u011bti ve struktu\u0159e ovl_aio_req p\u0159i sou\u010dasn\u00e9m prov\u00e1d\u011bn\u00ed v\u00edce operac\u00ed v OverlayFS nasazen\u00e9m na syst\u00e9mu soubor\u016f Ext4. Potenci\u00e1ln\u011b zranitelnost umo\u017e\u0148uje zv\u00fd\u0161en\u00ed opr\u00e1vn\u011bn\u00ed v syst\u00e9mu.\n<li class=\"l\"> CVE-2023-0590 \u2014 p\u0159\u00edstup k ji\u017e uvoln\u011bn\u00e9 oblasti pam\u011bti ve funkci qdisc_graft(). P\u0159edpokl\u00e1d\u00e1 se, \u017ee exploitace je omezena na p\u00e1d programu.\n<li class=\"l\"> CVE-2023-1249 \u2014 p\u0159\u00edstup k ji\u017e uvoln\u011bn\u00e9 oblasti pam\u011bti v k\u00f3du z\u00e1pisu coredump, co\u017e je d\u016fsledkem vynechan\u00e9ho vol\u00e1n\u00ed mmap_lock ve funkci file_files_note. P\u0159edpokl\u00e1d\u00e1 se, \u017ee exploitace je omezena na p\u00e1d programu.    <\/ul>\n<p>Zdroj: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=58857\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0412 \u044f\u0434\u0440\u0435 Linux \u0432 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u0444\u0430\u0439\u043b\u043e\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b OverlayFS \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2023-0386), \u043a\u043e\u0442\u043e\u0440\u0443\u044e \u043c\u043e\u0436\u043d\u043e \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c \u0434\u043b\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f root-\u0434\u043e\u0441\u0442\u0443\u043f\u0430 \u043d\u0430 \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u0445, \u0432 \u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u0443\u0441\u0442\u0430\u043d\u043e\u0432\u043b\u0435\u043d\u0430 \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u0430 FUS\u0415 \u0438 \u0440\u0430\u0437\u0440\u0435\u0448\u0435\u043d\u043e \u043c\u043e\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0430\u0437\u0434\u0435\u043b\u043e\u0432 OverlayFS \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u043c \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u043c (\u043d\u0430\u0447\u0438\u043d\u0430\u044f \u0441 \u044f\u0434\u0440\u0430 Linux 5.11 \u0441 \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u0435\u043c \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u0445 user namespace). \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0432 \u0432\u0435\u0442\u043a\u0435 \u044f\u0434\u0440\u0430 6.2. \u041f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u044e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0439 \u043f\u0430\u043a\u0435\u0442\u043e\u0432 \u0432 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 \u043c\u043e\u0436\u043d\u043e \u043f\u0440\u043e\u0441\u043b\u0435\u0434\u0438\u0442\u044c \u043d\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-107498","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=\"\u0412 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\u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 OverlayFS, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043f\u043e\u0432\u044b\u0441\u0438\u0442\u044c \u0441\u0432\u043e\u0438 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0438 | ProHoster","og:description":"\u0412 \u044f\u0434\u0440\u0435 Linux \u0432 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u0444\u0430\u0439\u043b\u043e\u0432\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b OverlayFS \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2023-0386), \u043a\u043e\u0442\u043e\u0440\u0443\u044e \u043c\u043e\u0436\u043d\u043e \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c \u0434\u043b\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f root-\u0434\u043e\u0441\u0442\u0443\u043f\u0430 \u043d\u0430 \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u0445, \u0432 \u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u0443\u0441\u0442\u0430\u043d\u043e\u0432\u043b\u0435\u043d\u0430 \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u0430 FUS\u0415 \u0438 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