{"id":55921,"date":"2020-02-01T00:00:00","date_gmt":"2020-01-31T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os"},"modified":"2020-02-18T14:04:05","modified_gmt":"2020-02-18T11:04:05","slug":"root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/news\/root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os","title":{"rendered":"Root zranite\u013enos\u0165 v sudo, ktor\u00e1 ovplyv\u0148uje Linux Mint a Elementary OS.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V utilit\u011b sudo<\/a><\/noindex>, pou\u017e\u00edvan\u00e9 na organizov\u00e1n\u00ed vykon\u00e1v\u00e1n\u00ed p\u0159\u00edkaz\u016f jm\u00e9nem jin\u00fdch u\u017eivatel\u016f, bola zisten\u00e1<\/a><\/noindex> zranite\u013enos\u0165 (CVE-2019-18634<\/a><\/noindex>), \u010do umo\u017e\u0148uje zv\u00fd\u0161i\u0165 svoje privil\u00e9gia v syst\u00e9me na pou\u017e\u00edvate\u013ea root. Probl\u00e9m sa prejavuje od verzie sudo 1.7.1 iba pri pou\u017eit\u00ed vo s\u00fabore \/etc\/sudoers vo\u013eby \u201epwfeedback\u201c, ktor\u00e1 je predvolene vypnut\u00e1, ale aktivovan\u00e1 v niektor\u00fdch distrib\u00faci\u00e1ch, ako s\u00fa Linux Mint a Elementary OS. Probl\u00e9m bol vyrie\u0161en\u00fd vo verzii sudo 1.8.31<\/a><\/noindex>, uverejnenej pred nieko\u013ek\u00fdmi hodinami. V distrib\u00faci\u00e1ch zranite\u013enos\u0165 zatia\u013e zost\u00e1va neopravena.<\/p>\n

Vo\u013eba \u201epwfeedback\u201c zap\u00edna zobrazenie znaku \u201e*\u201c po ka\u017edom zadanom znaku pri zad\u00e1van\u00ed hesla. Z d\u00f4vodu chyby<\/a><\/noindex> v implement\u00e1cii funkcie getln(), definovanej v s\u00fabore tgetpass.c, prenesen\u00fd cez \u0161tandardn\u00fd vstup (stdin) pr\u00edli\u0161 dlh\u00fd re\u0165azec s heslom za ur\u010dit\u00fdch podmienok nemus\u00ed vojs\u0165 do pridelen\u00e9ho bufra a prep\u00ed\u0161e in\u00e9 d\u00e1ta na z\u00e1sobn\u00edku. Preplnenie sa vyskytuje pri vykon\u00e1van\u00ed k\u00f3du sudo s pr\u00e1vami root.<\/p>\n

Podstata probl\u00e9mu spo\u010d\u00edva v tom, \u017ee pri pou\u017eit\u00ed \u0161peci\u00e1lneho znaku ^U (vymazanie riadku) a pri zlyhan\u00ed z\u00e1pisu sa k\u00f3d zodpovedn\u00fd za vymazanie zobrazen\u00fdch znakov \u201e*\u201c resetuje \u00fadaje o dostupnej ve\u013ekosti vyrovn\u00e1vacej pam\u00e4te, ale nevracia na p\u00f4vodn\u00fa hodnotu ukazovate\u013e na aktu\u00e1lnu poz\u00edciu vo vyrovn\u00e1vacej pam\u00e4ti. \u010eal\u0161\u00edm faktorom, ktor\u00fd podporuje zneu\u017eitie, je nedostatok automatick\u00e9ho vypnutia re\u017eimu \u201epwfeedback\u201c pri pr\u00edchode \u00fadajov nie z termin\u00e1lu, ale cez vstupn\u00fd pr\u00fad (tento nedostatok umo\u017e\u0148uje vytvori\u0165 podmienky pre vznik chyby z\u00e1pisu, napr\u00edklad na syst\u00e9moch s jednosmern\u00fdm) neozna\u010den\u00fdmi kan\u00e1lmi<\/a><\/noindex> chyba sa vyskytuje pri pokuse o z\u00e1pis za koniec kan\u00e1la na \u010d\u00edtanie).<\/p>\n

Ke\u010f\u017ee \u00fato\u010dn\u00edk m\u00f4\u017ee \u00faplne kontrolova\u0165 prep\u00edsanie \u00fadajov v z\u00e1sobn\u00edku, nie je \u0165a\u017ek\u00e9 vytvori\u0165 exploit, ktor\u00fd umo\u017en\u00ed zv\u00fd\u0161i\u0165 svoje privil\u00e9gia na pou\u017e\u00edvate\u013ea root. Probl\u00e9m m\u00f4\u017ee by\u0165 zneu\u017eit\u00fd ak\u00fdmko\u013evek pou\u017e\u00edvate\u013eom, bez oh\u013eadu na pr\u00e1va na pou\u017e\u00edvanie sudo a pr\u00edtomnos\u0165 \u0161pecifick\u00fdch nastaven\u00ed pre pou\u017e\u00edvate\u013ea v sudoers. Na zablokovanie probl\u00e9mu by sa malo zabezpe\u010di\u0165, \u017ee v \/etc\/sudoers nie je nastavenie \u201epwfeedback\u201c a v pr\u00edpade potreby ho vypn\u00fa\u0165 (\u201eDefaults !pwfeedback\u201c). Pre overenie pr\u00edtomnosti probl\u00e9mu m\u00f4\u017eete vykona\u0165 k\u00f3d:<\/p>\n

$ perl -e 'print((\u201eA\u201c x 100 . \u201e\u201c) x 50)' | sudo -S id
\n Heslo: Segmenta\u010dn\u00e1 chyba<\/p>\n

<\/a><\/noindex><\/p>\n

Zdroj: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u0443\u0442\u0438\u043b\u0438\u0442\u0435 sudo, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c\u043e\u0439 \u0434\u043b\u044f \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u043a\u043e\u043c\u0430\u043d\u0434 \u043e\u0442 \u0438\u043c\u0435\u043d\u0438 \u0434\u0440\u0443\u0433\u0438\u0445 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2019-18634), \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 \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u0434\u043e \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f root. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u043d\u0430\u0447\u0438\u043d\u0430\u044f \u0441 \u0432\u044b\u043f\u0443\u0441\u043a\u0430 sudo 1.7.1 \u0442\u043e\u043b\u044c\u043a\u043e \u043f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 \u0432 \u0444\u0430\u0439\u043b\u0435 \/etc\/sudoers \u043e\u043f\u0446\u0438\u0438 «pwfeedback», \u043a\u043e\u0442\u043e\u0440\u0430\u044f \u043e\u0442\u043a\u043b\u044e\u0447\u0435\u043d\u0430 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e, \u043d\u043e \u0430\u043a\u0442\u0438\u0432\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u0432 \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445, \u0442\u0430\u043a\u0438\u0445 \u043a\u0430\u043a Linux Mint \u0438 Elementary OS. […]<\/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-55921","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\udd47Root zranite\u013enos\u0165 v sudo, ktor\u00e1 ovplyv\u0148uje Linux Mint a Elementary OS | ProHoster","description":"V utilite sudo, ktor\u00e1 sa pou\u017e\u00edva na organizovanie vykon\u00e1vania pr\u00edkazov v mene in\u00fdch pou\u017e\u00edvate\u013eov,","canonical_url":"https:\/\/prohoster.info\/sk\/blog\/news\/root-uyazvimost-v-sudo-zatragivayushhaya-linux-mint-i-elementary-os","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"sk_SK","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\udd47Root-\u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 sudo, \u0437\u0430\u0442\u0440\u0430\u0433\u0438\u0432\u0430\u044e\u0449\u0430\u044f Linux Mint \u0438 Elementary OS | ProHoster","og:description":"\u0412 \u0443\u0442\u0438\u043b\u0438\u0442\u0435 sudo, 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