V Netfilter, jadre Linux, ktor\u00e9 sa pou\u017e\u00edva na filtrovanie a modifik\u00e1ciu sie\u0165ov\u00fdch paketov, bola zisten\u00e1 zranite\u013enos\u0165 (CVE-2021-22555), ktor\u00e1 umo\u017e\u0148uje lok\u00e1lnemu pou\u017e\u00edvate\u013eovi z\u00edska\u0165 privil\u00e9gi\u00e1 root v syst\u00e9me, dokonca aj v izolovanom konte. Na testovanie bol pripraven\u00fd pracovn\u00fd prototyp exploit-u, ktor\u00fd obch\u00e1dza zabezpe\u010dovacie mechanizmy KASLR, SMAP a SMEP. V\u00fdskumn\u00edk, ktor\u00fd zistil zranite\u013enos\u0165, dostal od Google odmenu vo v\u00fd\u0161ke 20 tis\u00edc dol\u00e1rov za objavenie met\u00f3dy obch\u00e1dzania izol\u00e1cie kontajnerov Kubernetes v klastre kCTF. <\/p>\n
Probl\u00e9m sa prejavuje od jadra 2.6.19, vydan\u00e9ho pred 15 rokmi, a je sp\u00f4soben\u00fd chybou v spracovate\u013eoch IPT_SO_SET_REPLACE a IP6T_SO_SET_REPLACE, ktor\u00e1 vedie k prete\u010deniu vyrovn\u00e1vacej pam\u00e4te pri odosielan\u00ed \u0161peci\u00e1lne naform\u00e1tovan\u00fdch parametrov cez volanie setsockopt v re\u017eime compat. Za norm\u00e1lnych okolnost\u00ed m\u00f4\u017ee vola\u0165 compat_setsockopt() iba pou\u017e\u00edvate\u013e root, ale potrebn\u00e9 opr\u00e1vnenia na uskuto\u010dnenie \u00fatoku m\u00f4\u017eu z\u00edska\u0165 aj neopr\u00e1vnen\u00ed pou\u017e\u00edvatelia v syst\u00e9moch so zapnutou podporou menov\u00fdch priestorov ident\u00edt pou\u017e\u00edvate\u013eov (user namespaces). <\/p>\n
Pou\u017e\u00edvate\u013e m\u00f4\u017ee vytvori\u0165 kontajner s oddelen\u00fdm pou\u017e\u00edvate\u013eom root a z neho vyu\u017e\u00edva\u0165 zranite\u013enos\u0165. Napr\u00edklad, \u201euser namespaces\u201c s\u00fa predvolene zapnut\u00e9 v Ubuntu a Fedora, ale nie s\u00fa aktivovan\u00e9 v Debian a RHEL. Oprava zranite\u013enosti bola prijat\u00e1 do jadra Linux 13. apr\u00edla. Aktualiz\u00e1cie bal\u00edkov u\u017e boli pripraven\u00e9 projektmi Debian, Arch Linux a Fedora. V Ubuntu, RHEL a SUSE s\u00fa aktualiz\u00e1cie v procese pr\u00edpravy. <\/p>\n
Probl\u00e9m vznik\u00e1 vo funkcii xt_compat_target_from_user() kv\u00f4li nespr\u00e1vnemu v\u00fdpo\u010dtu ve\u013ekosti pam\u00e4te pri ukladan\u00ed \u0161trukt\u00far jadra po konverzii z 32- na 64-bitov\u00e9 zobrazenie. Chyba umo\u017e\u0148uje zap\u00edsa\u0165 \u0161tyri nulov\u00e9 bajty na ak\u00fako\u013evek poz\u00edciu mimo vyhraden\u00e9ho buffera, obmedzen\u00fa posunom 0x4C. T\u00e1to mo\u017enos\u0165 bola dostato\u010dn\u00e1 na vytvorenie exploit-u, ktor\u00fd umo\u017e\u0148uje z\u00edska\u0165 pr\u00e1va root \u2014 prostredn\u00edctvom vy\u010distenia ukazovate\u013ea m_list->next v \u0161trukt\u00fare msg_msg sa vytvorili podmienky na pr\u00edstup k \u00fadajom po uvo\u013enen\u00ed pam\u00e4te (use-after-free), \u010do sa n\u00e1sledne vyu\u017eilo na z\u00edskanie inform\u00e1ci\u00ed o adres\u00e1ch a na zmenu in\u00fdch \u0161trukt\u00far manipul\u00e1ciou so syst\u00e9mov\u00fdm volan\u00edm msgsnd(). \u0412 Netfilter, \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u044f\u0434\u0440\u0430 Linux, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c\u043e\u0439 \u0434\u043b\u044f \u0444\u0438\u043b\u044c\u0442\u0440\u0430\u0446\u0438\u0438 \u0438 \u043c\u043e\u0434\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u0438 \u0441\u0435\u0442\u0435\u0432\u044b\u0445 \u043f\u0430\u043a\u0435\u0442\u043e\u0432, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-22555), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0438 root \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435, \u0432 \u0442\u043e\u043c \u0447\u0438\u0441\u043b\u0435 \u043d\u0430\u0445\u043e\u0434\u044f\u0441\u044c \u0432 \u0438\u0437\u043e\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c \u043a\u043e\u043d\u0442\u0435\u0439\u043d\u0435\u0440\u0435. \u0414\u043b\u044f \u0442\u0435\u0441\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u043f\u043e\u0434\u0433\u043e\u0442\u043e\u0432\u043b\u0435\u043d \u0440\u0430\u0431\u043e\u0447\u0438\u0439 \u043f\u0440\u043e\u0442\u043e\u0442\u0438\u043f \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430, \u043e\u0431\u0445\u043e\u0434\u044f\u0449\u0438\u0439 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u044b \u0437\u0430\u0449\u0438\u0442\u044b KASLR, SMAP \u0438 SMEP. \u0418\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c, \u0432\u044b\u044f\u0432\u0438\u0432\u0448\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043f\u043e\u043b\u0443\u0447\u0438\u043b \u043e\u0442 Google \u0432\u043e\u0437\u043d\u0430\u0433\u0440\u0430\u0436\u0434\u0435\u043d\u0438\u0435, \u0440\u0430\u0437\u043c\u0435\u0440\u043e\u043c 20 \u0442\u044b\u0441\u044f\u0447 \u0434\u043e\u043b\u043b\u0430\u0440\u043e\u0432, \u0437\u0430 […]<\/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-100767","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\udd47Zranite\u013enos\u0165 v subsyst\u00e9me jadra Linux Netfilter | ProHoster","description":"V Netfilter, subsyst\u00e9me jadra Linux pou\u017e\u00edvanom na filtrovanie a modifik\u00e1ciu sie\u0165ov\u00fdch paketov, bola zisten\u00e1 zranite\u013enos\u0165 (CVE-2021-22555), ktor\u00e1 umo\u017e\u0148uje miestnemu u\u017e\u00edvate\u013eovi z\u00edska\u0165 privilegium roota v syst\u00e9me, 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Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"