{"id":94510,"date":"2020-09-18T01:41:56","date_gmt":"2020-09-17T23:41:56","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/realizacziya-kontrollera-domena-v-samba-okazalas-podverzhena-uyazvimosti-zerologin"},"modified":"2020-09-18T01:41:56","modified_gmt":"2020-09-17T23:41:56","slug":"realizacziya-kontrollera-domena-v-samba-okazalas-podverzhena-uyazvimosti-zerologin","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/news\/realizacziya-kontrollera-domena-v-samba-okazalas-podverzhena-uyazvimosti-zerologin","title":{"rendered":"Implement\u00e1cia riadiacej jednotky dom\u00e9ny v Samba sa uk\u00e1zala by\u0165 zranite\u013en\u00e1 vo\u010di ZeroLogin.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V\u00fdvoj\u00e1ri projektu Samba varovali<\/a><\/noindex> pou\u017e\u00edvate\u013eov, \u017ee ned\u00e1vno bola zisten\u00e1<\/a><\/noindex> zranite\u013enos\u0165 ZeroLogin (CVE-2020-1472<\/a><\/noindex>) prejavuje sa<\/a><\/noindex> aj v implement\u00e1cii riadiacej jednotky dom\u00e9ny zalo\u017eenej na Samba. Zranite\u013enos\u0165 je sp\u00f4soben\u00e1<\/a><\/noindex> vypl\u00fdva z nedostatkov v protokole MS-NRPC a kryptografickom algoritme AES-CFB8, a pri \u00faspe\u0161nej exploit\u00e1cii umo\u017e\u0148uje \u00fato\u010dn\u00edkovi z\u00edska\u0165 administr\u00e1torsk\u00fd pr\u00edstup v riadiacej jednotke dom\u00e9ny.<\/p>\n

Podstatou zranite\u013enosti je, \u017ee protokol MS-NRPC (Netlogon Remote Protocol) umo\u017e\u0148uje pri v\u00fdmene autentifika\u010dn\u00fdch \u00fadajov prejs\u0165 na pou\u017eitie RPC pripojenia bez \u0161ifrovania. Po tomto m\u00f4\u017ee \u00fato\u010dn\u00edk vyu\u017ei\u0165 medzeru v algoritme AES-CFB8 na fal\u0161ovanie \u00faspe\u0161n\u00e9ho prihl\u00e1senia. Na prihl\u00e1senie s administr\u00e1torsk\u00fdmi pr\u00e1vami je v priemere potrebn\u00fdch pribli\u017ene 256 pokusov o fal\u0161ovanie. Na vykonanie \u00fatoku nie je potrebn\u00e9 ma\u0165 platn\u00fd \u00fa\u010det na ovl\u00e1dacom dom\u00e9ne \u2013 pokusy o fal\u0161ovanie je mo\u017en\u00e9 vykon\u00e1va\u0165 s pou\u017eit\u00edm nespr\u00e1vneho hesla. \u017diados\u0165 o autentifik\u00e1ciu prostredn\u00edctvom NTLM bude presmerovan\u00e1 na ovl\u00e1dac\u00ed dom\u00e9nov\u00fd server, ktor\u00fd vr\u00e1ti odmietnutie pr\u00edstupu, ale \u00fato\u010dn\u00edk m\u00f4\u017ee tento odpove\u010f podvrhn\u00fa\u0165 a \u00fatokn\u00e1 s\u00fastava si bude myslie\u0165, \u017ee prihl\u00e1senie bolo \u00faspe\u0161n\u00e9.<\/p>\n

Vo Samba sa zranite\u013enos\u0165 prejavuje len v syst\u00e9moch, ktor\u00e9 nepou\u017e\u00edvaj\u00fa nastavenie \u201eserver schannel = yes\u201c, ktor\u00e9 je od verzie Samba 4.8 nastaven\u00e9 ako predvolen\u00e9. Konkr\u00e9tne m\u00f4\u017eu by\u0165 ohrozen\u00e9 syst\u00e9my s nastaveniami \u201eserver schannel = no\u201c a \u201eserver schannel = auto\u201c, ktor\u00e9 umo\u017e\u0148uj\u00fa v Samba pou\u017ei\u0165 tie ist\u00e9 nedostatky v algoritme AES-CFB8, ak\u00e9 s\u00fa aj vo Windows. <\/p>\n

Pri pou\u017eit\u00ed pripravenej pre Windows referen\u010dnej prototypu exploitu<\/a><\/noindex>, v Samba sa aktivuje iba volanie ServerAuthenticate3, zatia\u013e \u010do oper\u00e1cia ServerPasswordSet2 kon\u010d\u00ed chybou (exploit si vy\u017eaduje prisp\u00f4sobenie pre Samba). O funk\u010dnosti alternat\u00edvnych exploitov (1<\/a><\/noindex>, 2<\/a><\/noindex>, 3<\/a><\/noindex>, 4<\/a><\/noindex>) nie s\u00fa dostupn\u00e9 \u017eiadne inform\u00e1cie. Sna\u017ei\u0165 sa sledova\u0165 pokusy o \u00fatok na syst\u00e9my je mo\u017en\u00e9 cez anal\u00fdzu zaznamen\u00e1vania zmien s zmienkami ServerAuthenticate3 a ServerPasswordSet v logoch auditu Samba.<\/p>\n

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

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

\u0420\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0447\u0438\u043a\u0438 \u043f\u0440\u043e\u0435\u043a\u0442\u0430 Samba \u043f\u0440\u0435\u0434\u0443\u043f\u0440\u0435\u0434\u0438\u043b\u0438 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439, \u0447\u0442\u043e \u043d\u0435\u0434\u0430\u0432\u043d\u043e \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u043d\u0430\u044f \u0432 Windows \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c ZeroLogin (CVE-2020-1472) \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0438 \u0432 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u043b\u0435\u0440\u0430 \u0434\u043e\u043c\u0435\u043d\u0430 \u043d\u0430 \u0431\u0430\u0437\u0435 Samba. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432\u044b\u0437\u0432\u0430\u043d\u0430 \u043d\u0435\u0434\u043e\u0440\u0430\u0431\u043e\u0442\u043a\u0430\u043c\u0438 \u0432 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0435 MS-NRPC \u0438 \u043a\u0440\u0438\u043f\u0442\u043e\u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c\u0435 AES-CFB8, \u0438 \u043f\u0440\u0438 \u0443\u0441\u043f\u0435\u0448\u043d\u043e\u0439 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u0437\u043b\u043e\u0443\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u0438\u043a\u0443 \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u0434\u043e\u0441\u0442\u0443\u043f \u0430\u0434\u043c\u0438\u043d\u0438\u0441\u0442\u0440\u0430\u0442\u043e\u0440\u0430 \u0432 \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u043b\u0435\u0440\u0435 \u0434\u043e\u043c\u0435\u043d\u0430. \u0421\u0443\u0442\u044c \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 \u0442\u043e\u043c, \u0447\u0442\u043e \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b MS-NRPC (Netlogon Remote Protocol) \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u043f\u0440\u0438 […]<\/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-94510","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\udd47Implement\u00e1cia riadiacej jednotky dom\u00e9ny v Samba sa uk\u00e1zala by\u0165 zranite\u013en\u00e1 vo\u010di ZeroLogin | ProHoster","description":"V\u00fdvoj\u00e1ri projektu Samba varovali pou\u017e\u00edvate\u013eov, \u017ee 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