{"id":101245,"date":"2021-09-10T22:22:37","date_gmt":"2021-09-10T20:22:37","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick"},"modified":"2021-09-10T22:22:37","modified_gmt":"2021-09-10T20:22:37","slug":"uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick","title":{"rendered":"Zranitelnost v Ghostscript, kter\u00e1 je vyu\u017e\u00edv\u00e1na prost\u0159ednictv\u00edm ImageMagick","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V Ghostscript, sad\u011b n\u00e1stroj\u016f pro zpracov\u00e1n\u00ed, p\u0159evod a generaci dokument\u016f ve form\u00e1tech PostScript a PDF, byla zji\u0161t\u011bna kritick\u00e1 zranitelnost (CVE-2021-3781), kter\u00e1 umo\u017e\u0148uje vykon\u00e1n\u00ed libovoln\u00e9ho k\u00f3du p\u0159i zpracov\u00e1n\u00ed speci\u00e1ln\u011b upraven\u00e9ho souboru. Na probl\u00e9m p\u016fvodn\u011b upozornil Emil Lerner, kter\u00fd o zranitelnosti hovo\u0159il 25. srpna na konferenci ZeroNights X konan\u00e9 v Petrohrad\u011b (v jeho prezentaci bylo pops\u00e1no, jak Emil v r\u00e1mci program\u016f bug bounty zneu\u017eil tuto zranitelnost k z\u00edsk\u00e1n\u00ed odm\u011bn za demonstraci \u00fatok\u016f na slu\u017eby AirBNB, Dropbox a Yandex.Nemovitost). <\/p>\n

5. z\u00e1\u0159\u00ed byl zve\u0159ejn\u011bn ve\u0159ejn\u011b dostupn\u00fd funk\u010dn\u00ed exploit, kter\u00fd umo\u017e\u0148uje \u00fato\u010dit na syst\u00e9my s Ubuntu 20.04 prost\u0159ednictv\u00edm p\u0159enosu speci\u00e1ln\u011b upraven\u00e9ho dokumentu, nahran\u00e9ho pod z\u00e1minkou obr\u00e1zku, ke skriptu PHP b\u011b\u017e\u00edc\u00edmu na serveru, kter\u00fd vyu\u017e\u00edv\u00e1 bal\u00ed\u010dek php-imagemagick. Podle p\u0159edb\u011b\u017en\u00fdch informac\u00ed byl podobn\u00fd exploit v ob\u011bhu ji\u017e od b\u0159ezna. Byla hl\u00e1\u0161ena mo\u017enost \u00fatoku na syst\u00e9my s GhostScript 9.50, ale uk\u00e1zalo se, \u017ee zranitelnost se projevuje i ve v\u0161ech n\u00e1sleduj\u00edc\u00edch verz\u00edch GhostScript, v\u010detn\u011b vyv\u00edjen\u00e9 verze 9.55 z Gitu. <\/p>\n

Oprava byla navr\u017eena 8. z\u00e1\u0159\u00ed a po recenzov\u00e1n\u00ed byla p\u0159ijata do repozit\u00e1\u0159e GhostScript 9. z\u00e1\u0159\u00ed. V mnoha distribuc\u00edch probl\u00e9m z\u016fst\u00e1v\u00e1 dodnes neopraven\u00fd (stav zve\u0159ejn\u011bn\u00ed aktualizac\u00ed lze zkontrolovat na str\u00e1nk\u00e1ch Debianu, Ubuntu, Fedora, SUSE, RHEL, Arch Linux, FreeBSD, NetBSD). Uvoln\u011bn\u00ed GhostScript s odstran\u011bn\u00edm zranitelnosti se pl\u00e1nuje p\u0159ed koncem m\u011bs\u00edce. <\/p>\n

Probl\u00e9m je zp\u016fsoben mo\u017enost\u00ed obej\u00edt izola\u010dn\u00ed re\u017eim «-dSAFER» kv\u016fli nedostate\u010dn\u00e9 kontrole parametr\u016f Postscript za\u0159\u00edzen\u00ed «%pipe%», co\u017e umo\u017enilo prov\u00e1d\u011bn\u00ed libovoln\u00fdch shellov\u00fdch p\u0159\u00edkaz\u016f. Nap\u0159\u00edklad pro spu\u0161t\u011bn\u00ed utility id v dokumentu sta\u010d\u00ed zadat \u0159et\u011bzec «(%pipe%\/tmp\/&id)(w)file» nebo «(%pipe%\/tmp\/;id)(r)file». <\/p>\n

P\u0159ipom\u00edn\u00e1me, \u017ee zranitelnosti v Ghostscript p\u0159edstavuj\u00ed zv\u00fd\u0161en\u00e9 nebezpe\u010d\u00ed, nebo\u0165 tento bal\u00ed\u010dek je vyu\u017e\u00edv\u00e1n v mnoha popul\u00e1rn\u00edch aplikac\u00edch pro zpracov\u00e1n\u00ed form\u00e1t\u016f PostScript a PDF. Nap\u0159\u00edklad se Ghostscript anga\u017euje v procesu vytv\u00e1\u0159en\u00ed n\u00e1hled\u016f na plo\u0161e, p\u0159i pozad\u00ed indexace dat a p\u0159i p\u0159evodu obr\u00e1zk\u016f. Pro \u00fasp\u011b\u0161n\u00fd \u00fatok je v mnoha p\u0159\u00edpadech dosta\u010duj\u00edc\u00ed jednodu\u0161e na\u010d\u00edst soubor s exploitem nebo zobrazit adres\u00e1\u0159 s n\u00edm v spr\u00e1vci soubor\u016f, kter\u00fd podporuje zobrazen\u00ed n\u00e1hled\u016f dokument\u016f, nap\u0159\u00edklad v Nautilus. <\/p>\n

Zranitelnosti v Ghostscript lze tak\u00e9 vyu\u017e\u00edt prost\u0159ednictv\u00edm zpracovatel\u016f obr\u00e1zk\u016f zalo\u017een\u00fdch na bal\u00edc\u00edch ImageMagick a GraphicsMagick, p\u0159en\u00e1\u0161en\u00edm JPEG nebo PNG souboru, ve kter\u00e9m m\u00edsto obr\u00e1zku je k\u00f3d PostScript (takov\u00fd soubor bude zpracov\u00e1n v Ghostscript, proto\u017ee MIME typ je rozpozn\u00e1v\u00e1n podle obsahu, nikoli se spol\u00e9haj\u00edc na p\u0159\u00edponu).
\n
Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 Ghostscript, \u043d\u0430\u0431\u043e\u0440\u0435 \u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u0434\u043b\u044f \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438, \u043f\u0440\u0435\u043e\u0431\u0440\u0430\u0437\u043e\u0432\u0430\u043d\u0438\u044f \u0438 \u0433\u0435\u043d\u0435\u0440\u0430\u0446\u0438\u0438 \u0434\u043e\u043a\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0430\u0445 PostScript \u0438 PDF, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u043a\u0440\u0438\u0442\u0438\u0447\u0435\u0441\u043a\u0430\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-3781), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0439 \u043a\u043e\u0434 \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\u043e\u0433\u043e \u0444\u0430\u0439\u043b\u0430. \u0418\u0437\u043d\u0430\u0447\u0430\u043b\u044c\u043d\u043e \u043d\u0430 \u043d\u0430\u043b\u0438\u0447\u0438\u0435 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u043e\u0431\u0440\u0430\u0442\u0438\u043b \u0432\u043d\u0438\u043c\u0430\u043d\u0438\u0435 \u042d\u043c\u0438\u043b\u044c \u041b\u0435\u0440\u043d\u0435\u0440, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u0440\u0430\u0441\u0441\u043a\u0430\u0437\u0430\u043b \u043e\u0431 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 25 \u0430\u0432\u0433\u0443\u0441\u0442\u0430 \u043d\u0430 \u043f\u0440\u043e\u0448\u0435\u0434\u0448\u0435\u0439 \u0432 \u0421\u0430\u043d\u043a\u0442-\u041f\u0435\u0442\u0435\u0440\u0431\u0443\u0440\u0433\u0435 \u043a\u043e\u043d\u0444\u0435\u0440\u0435\u043d\u0446\u0438\u0438 ZeroNights X (\u0432 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PostScript a PDF, byla odhalena kritick\u00e1 zranitelnost (CVE-2021-3781), kter\u00e1 umo\u017e\u0148uje prov\u00e9st libovoln\u00fd k\u00f3d.","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-ghostscript-ekspluatiruemaya-cherez-imagemagick","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"cs_CZ","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\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 Ghostscript, \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0438\u0440\u0443\u0435\u043c\u0430\u044f \u0447\u0435\u0440\u0435\u0437 ImageMagick | 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