{"id":154530,"date":"2026-01-20T23:11:56","date_gmt":"2026-01-20T21:11:56","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-telnetd-pozvolyayushhaya-podklyuchitsya-s-pravami-root-bez-autentifikaczii"},"modified":"2026-01-20T23:11:56","modified_gmt":"2026-01-20T21:11:56","slug":"uyazvimost-v-telnetd-pozvolyayushhaya-podklyuchitsya-s-pravami-root-bez-autentifikaczii","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pl\/blog\/news\/uyazvimost-v-telnetd-pozvolyayushhaya-podklyuchitsya-s-pravami-root-bez-autentifikaczii","title":{"rendered":"Vulnerabilno\u015b\u0107 w telnetd, umo\u017cliwiaj\u0105ca po\u0142\u0105czenie z uprawnieniami roota bez autoryzacji","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

W serwerze telnetd z pakietu GNU InetUtils wykryto luk\u0119, kt\u00f3ra pozwala na po\u0142\u0105czenie jako dowolny u\u017cytkownik, w tym u\u017cytkownik root, bez weryfikacji has\u0142a. Numer CVE nie zosta\u0142 jeszcze przypisany. Luka ta pojawi\u0142a si\u0119 od wersji InetUtils 1.9.3 (2015 rok) i pozostaje nieusuni\u0119ta w aktualnym wydaniu 2.7.0. Poprawka jest dost\u0119pna w formie \u0142atek (1, 2). <\/p>\n

Problem wynika z tego, \u017ce do sprawdzenia has\u0142a proces telnetd wywo\u0142uje narz\u0119dzie \"usr\/bin\/login\", przekazuj\u0105c jako argument nazw\u0119 u\u017cytkownika podan\u0105 przez klienta podczas \u0142\u0105czenia si\u0119 z serwera<\/a>. Narz\u0119dzie \"login\" obs\u0142uguje opcj\u0119 \"-f\", kt\u00f3ra pozwala na zalogowanie si\u0119 bez przeprowadzania autoryzacji (zak\u0142ada si\u0119, \u017ce ta opcja jest u\u017cywana, gdy u\u017cytkownik ju\u017c przeszed\u0142 weryfikacj\u0119). W ten spos\u00f3b, je\u015bli uda si\u0119 wstawi\u0107 opcj\u0119 \"-f\" w nazwie u\u017cytkownika, mo\u017cna po\u0142\u0105czy\u0107 si\u0119 bez sprawdzania has\u0142a. <\/p>\n

Przy normalnym po\u0142\u0105czeniu u\u017cycie nazwy u\u017cytkownika w postaci \"-f root\" nie jest mo\u017cliwe, ale w telnet istnieje tryb automatycznego po\u0142\u0105czenia aktywowany opcj\u0105 \"-a\". W tym trybie nazwa u\u017cytkownika nie jest pobierana z wiersza polece\u0144, ale jest przekazywana przez zmienn\u0105 \u015brodowiskow\u0105 USER. Przy wywo\u0142aniu narz\u0119dzia login warto\u015b\u0107 tej zmiennej \u015brodowiskowej by\u0142a wstawiana bez dodatkowej weryfikacji i bez eskapowania znak\u00f3w specjalnych. W ten spos\u00f3b, aby po\u0142\u0105czy\u0107 si\u0119 jako u\u017cytkownik root, wystarczy ustawi\u0107 w zmiennej \u015brodowiskowej USER warto\u015b\u0107 \"-f root\" i po\u0142\u0105czy\u0107 si\u0119 z serwerem telnet, podaj\u0105c opcj\u0119 \"-a\": $ USER='-f root' telnet -a nazwa_serwera <\/p>\n

Zmienione w celu wprowadzenia luki do kodu telnetd w marcu 2015 roku by\u0142o zwi\u0105zane z rozwi\u0105zaniem problemu, kt\u00f3ry uniemo\u017cliwia\u0142 ustalenie nazwy u\u017cytkownika w trybie autologin bez uwierzytelnienia w Kerberos. W ramach rozwi\u0105zania dodano wsparcie dla przekazywania nazwy u\u017cytkownika w trybie autologin przez zmienn\u0105 \u015brodowiskow\u0105, ale zapomniano doda\u0107 weryfikacj\u0119 poprawno\u015bci nazwy u\u017cytkownika z tej zmiennej.
\n
\u0179r\u00f3d\u0142o: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u0441\u0435\u0440\u0432\u0435\u0440\u0435 telnetd \u0438\u0437 \u043d\u0430\u0431\u043e\u0440\u0430 GNU InetUtils \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043f\u043e\u0434\u043a\u043b\u044e\u0447\u0438\u0442\u044c\u0441\u044f \u043f\u043e\u0434 \u043b\u044e\u0431\u044b\u043c \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u043c, \u0432\u043a\u043b\u044e\u0447\u0430\u044f \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f root, \u0431\u0435\u0437 \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u043f\u0430\u0440\u043e\u043b\u044f. CVE-\u0438\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440 \u043f\u043e\u043a\u0430 \u043d\u0435 \u043f\u0440\u0438\u0441\u0432\u043e\u0435\u043d. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u043d\u0430\u0447\u0438\u043d\u0430\u044f \u0441 \u0432\u0435\u0440\u0441\u0438\u0438 InetUtils 1.9.3 (2015 \u0433\u043e\u0434) \u0438 \u043e\u0441\u0442\u0430\u0451\u0442\u0441\u044f \u043d\u0435\u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u043d\u043e\u0439 \u0432 \u0430\u043a\u0442\u0443\u0430\u043b\u044c\u043d\u043e\u043c \u0432\u044b\u043f\u0443\u0441\u043a\u0435 2.7.0. \u0418\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u0435 \u0434\u043e\u0441\u0442\u0443\u043f\u043d\u043e \u0432 \u0444\u043e\u0440\u043c\u0435 \u043f\u0430\u0442\u0447\u0435\u0439 (1, 2). \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0432\u044b\u0437\u0432\u0430\u043d\u0430 \u0442\u0435\u043c, \u0447\u0442\u043e \u0434\u043b\u044f \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u043f\u0430\u0440\u043e\u043b\u044f \u043f\u0440\u043e\u0446\u0435\u0441\u0441 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-154530","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\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\udd47Luka w telnetd, kt\u00f3ra pozwala na po\u0142\u0105czenie z prawami root bez uwierzytelnienia | ProHoster","description":"W serwerze telnetd z pakietu GNU InetUtils wykryto luk\u0119, kt\u00f3ra pozwala na po\u0142\u0105czenie jako dowolny u\u017cytkownik, w 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