{"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\/hu\/blog\/news\/uyazvimost-v-telnetd-pozvolyayushhaya-podklyuchitsya-s-pravami-root-bez-autentifikaczii","title":{"rendered":"Biztons\u00e1gi r\u00e9s a telnetd-ben, amely lehet\u0151v\u00e9 teszi a root jogosults\u00e1g n\u00e9lk\u00fcli kapcsol\u00f3d\u00e1st","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A GNU InetUtils telnetd server vulnerability has been identified that allows connection as any user, including the root user, without password verification. No CVE identifier has been assigned yet. The vulnerability exists starting from InetUtils version 1.9.3 (2015) and remains unpatched in the current release 2.7.0. A fix is available in the form of patches (1, 2). <\/p>\n

A probl\u00e9ma abb\u00f3l ad\u00f3dik, hogy a jelsz\u00f3 ellen\u0151rz\u00e9s\u00e9hez a telnetd folyamat a \"\\\/usr\\\/bin\\\/login\" seg\u00e9drutin sz\u00f3t h\u00edvja meg, \u00e1tadva a felhaszn\u00e1l\u00f3n\u00e9v argumentumot, amelyet a kliens a csatlakoz\u00e1skor megadott. szerverhez<\/a>A \"login\" seg\u00e9drutin t\u00e1mogatja a \"-f\" opci\u00f3t, amely lehet\u0151v\u00e9 teszi a bejelentkez\u00e9st hiteles\u00edt\u00e9s v\u00e9grehajt\u00e1sa n\u00e9lk\u00fcl (az opci\u00f3 azt felt\u00e9telezi, hogy a felhaszn\u00e1l\u00f3 m\u00e1r \u00e1tesett az ellen\u0151rz\u00e9sen). Ebb\u0151l k\u00f6vetkez\u0151en, ha siker\u00fcl a \"-f\" opci\u00f3t a felhaszn\u00e1l\u00f3n\u00e9vbe helyettes\u00edteni, akkor a jelsz\u00f3 ellen\u0151rz\u00e9se n\u00e9lk\u00fcl is csatlakozni lehet. <\/p>\n

Norm\u00e1l csatlakoz\u00e1s eset\u00e9n nem lehet olyan felhaszn\u00e1l\u00f3nevet haszn\u00e1lni, mint a \"-f root\", de a telnet rendelkezik automatikus csatlakoz\u00e1si m\u00f3ddal, amelyet az \"-a\" opci\u00f3 aktiv\u00e1l. Ebben a m\u00f3dban a felhaszn\u00e1l\u00f3n\u00e9v nem a parancssorb\u00f3l, hanem a USER k\u00f6rnyezeti v\u00e1ltoz\u00f3n kereszt\u00fcl ker\u00fcl \u00e1tad\u00e1sra. A login seg\u00e9drutin megh\u00edv\u00e1sakor ennek a k\u00f6rnyezeti v\u00e1ltoz\u00f3nak az \u00e9rt\u00e9ke ellen\u0151rz\u00e9s n\u00e9lk\u00fcl \u00e9s speci\u00e1lis karakterek escapedel\u00e9se n\u00e9lk\u00fcl helyettes\u00edt\u00e9sre ker\u00fcl. \u00cdgy a root felhaszn\u00e1l\u00f3k\u00e9nt val\u00f3 csatlakoz\u00e1shoz elegend\u0151 be\u00e1ll\u00edtani a USER k\u00f6rnyezeti v\u00e1ltoz\u00f3 \u00e9rt\u00e9k\u00e9t \"-f root\"-ra, \u00e9s csatlakozni a telnet-szerverhez az \"-a\" opci\u00f3 megad\u00e1s\u00e1val: $ USER='-f root' telnet -a szerver_neve <\/p>\n

The change that led to the vulnerability was added to the telnetd code in March 2015 and was related to solving a problem that prevented determining the username in autologin mode without authentication in Kerberos. To resolve this, support was added for passing the username for autologin mode through an environment variable, but the check for the validity of the username from the environment variable was forgotten.
\n
Forr\u00e1s: 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, 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