{"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\/sv\/blog\/news\/uyazvimost-v-telnetd-pozvolyayushhaya-podklyuchitsya-s-pravami-root-bez-autentifikaczii","title":{"rendered":"En s\u00e5rbarhet i telnetd som m\u00f6jligg\u00f6r anslutning med root-r\u00e4ttigheter utan autentisering.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

En telnetd-server fr\u00e5n GNU InetUtils har en s\u00e5rbarhet identifierats som g\u00f6r det m\u00f6jligt att ansluta som vilken anv\u00e4ndare som helst, inklusive root-anv\u00e4ndaren, utan l\u00f6senordsverifiering. En CVE-identifierare har \u00e4nnu inte tilldelats. S\u00e5rbarheten f\u00f6religger fr\u00e5n och med version InetUtils 1.9.3 (2015) och kvarst\u00e5r ofixad i den aktuella versionen 2.7.0. En patch finns tillg\u00e4nglig (1, 2). <\/p>\n

Problemet orsakas av att f\u00f6r att verifiera l\u00f6senordet anropar processen telnetd verktyget \u00ab\/usr\/bin\/login\u00bb, med anv\u00e4ndarnamnet som argument, som anges av klienten vid anslutning. servern<\/a>Verktyget \u00ablogin\u00bb har alternativet \u00ab-f\u00bb, vilket m\u00f6jligg\u00f6r inloggning utan autentisering (det antas att detta alternativ anv\u00e4nds om anv\u00e4ndaren redan har verifierats). S\u00e5ledes, om man lyckas infoga alternativet \u00ab-f\u00bb i anv\u00e4ndarnamnet, kan man ansluta utan att kontrollera l\u00f6senordet. <\/p>\n

Vid vanlig anslutning g\u00e5r det inte att anv\u00e4nda anv\u00e4ndarnamnet \u00ab-f root\u00bb, men i telnet finns det ett automatiskt anslutningsl\u00e4ge som aktiveras med alternativet \u00ab-a\u00bb. I detta l\u00e4ge h\u00e4mtas anv\u00e4ndarnamnet inte fr\u00e5n kommandoraden utan skickas via milj\u00f6variabeln USER. Vid anrop av verktyget login infogades v\u00e4rdet av denna milj\u00f6variabel utan ytterligare kontroll och utan att specialtecken skulle undvikas. D\u00e4rf\u00f6r \u00e4r det tillr\u00e4ckligt f\u00f6r att ansluta som anv\u00e4ndaren root att s\u00e4tta v\u00e4rdet \u00ab-f root\u00bb i milj\u00f6variabeln USER och ansluta till telnet-servern genom att ange alternativet \u00ab-a\u00bb: $ USER='-f root' telnet -a server_namn <\/p>\n

\u00c4ndringen som ledde till s\u00e5rbarheten lades till i telnetd-koden i mars 2015 och var kopplad till att l\u00f6sa ett problem som f\u00f6rhindrade identifiering av anv\u00e4ndarnamn i autologin-l\u00e4get utan autentisering i Kerberos. Som l\u00f6sning lades st\u00f6d f\u00f6r att \u00f6verf\u00f6ra anv\u00e4ndarnamn f\u00f6r autologin-l\u00e4get via en milj\u00f6variabel till, men man gl\u00f6mde att l\u00e4gga till valideringen av anv\u00e4ndarnamnet fr\u00e5n milj\u00f6variabeln.
\n
K\u00e4lla: 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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