{"id":87197,"date":"2020-07-05T07:42:02","date_gmt":"2020-07-05T05:42:02","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-ssh-klientah-openssh-i-putty"},"modified":"2020-07-05T07:42:02","modified_gmt":"2020-07-05T05:42:02","slug":"uyazvimost-v-ssh-klientah-openssh-i-putty","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-ssh-klientah-openssh-i-putty","title":{"rendered":"Sebezhet\u0151s\u00e9g az OpenSSH \u00e9s PuTTY SSH kliensekn\u00e9l","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

OpenSSH \u00e9s PuTTY SSH-kliensekben identified<\/a><\/noindex> vulnerability<\/a><\/noindex> (CVE-2020-14002<\/a><\/noindex> PuTTY-ban \u00e9s CVE-2020-14145<\/a><\/noindex> OpenSSH-ban), ami az adatveszt\u00e9shez vezet a kapcsolat meger\u0151s\u00edt\u00e9si algoritmus\u00e1ban. A sebezhet\u0151s\u00e9g lehet\u0151v\u00e9 teszi a t\u00e1mad\u00f3 sz\u00e1m\u00e1ra, aki k\u00e9pes lehallgatni a kliens forgalm\u00e1t (p\u00e9ld\u00e1ul, amikor a felhaszn\u00e1l\u00f3 egy \u00e1ltala vez\u00e9relt vezet\u00e9k n\u00e9lk\u00fcli hozz\u00e1f\u00e9r\u00e9si ponthoz csatlakozik), hogy meghat\u00e1rozza a kliens kezdeti csatlakoz\u00e1si k\u00eds\u00e9rlet\u00e9t a hoszthoz, amikor a kliens m\u00e9g nem t\u00e1rolta a hoszt kulcs\u00e1t. <\/p>\n

Tudva, hogy a kliens el\u0151sz\u00f6r pr\u00f3b\u00e1l csatlakozni \u00e9s m\u00e9g nincs a kulcsa, a t\u00e1mad\u00f3 \u00e1tir\u00e1ny\u00edthatja a kapcsolatot (MITM) \u00e9s a kliensnek a saj\u00e1t hoszt kulcs\u00e1t adhatja, amelyet az SSH-kliens a c\u00e9lhoszt kulcs\u00e1nak tekint, ha nem ellen\u0151rzi a kulcs ujjlenyomat\u00e1t. \u00cdgy a t\u00e1mad\u00f3 MITM-t hozhat l\u00e9tre an\u00e9lk\u00fcl, hogy gyan\u00fat keltett volna a felhaszn\u00e1l\u00f3ban, \u00e9s figyelmen k\u00edv\u00fcl hagyhatja azokat a munkameneteket, ahol a kliens m\u00e1r t\u00e1rolt hoszt kulcsokkal rendelkezik, mivel a kulcsok hamis\u00edt\u00e1sa figyelmeztet\u00e9st okozna a hoszt kulcs\u00e1nak megv\u00e1ltoz\u00e1s\u00e1r\u00f3l. A t\u00e1mad\u00e1s a felhaszn\u00e1l\u00f3k felel\u0151tlens\u00e9g\u00e9n alapul, akik nem v\u00e9geznek manu\u00e1lis ellen\u0151rz\u00e9st a hoszt kulcs\u00e1nak ujjlenyomata eset\u00e9n csatlakoz\u00e1skor. Azok, akik ellen\u0151rzik a kulcsok ujjlenyomatait, v\u00e9dve vannak az ilyen t\u00edpus\u00fa t\u00e1mad\u00e1sok ellen.<\/p>\n

A csatlakoz\u00e1s els\u0151 k\u00eds\u00e9rlet\u00e9nek meghat\u00e1roz\u00e1s\u00e1hoz haszn\u00e1lt jel az al\u00e1\u00edr\u00e1s algoritmusok t\u00e1mogat\u00e1s\u00e1nak sorrendj\u00e9nek megv\u00e1ltoz\u00e1sa. Ha a kliens el\u0151sz\u00f6r csatlakozik, alap\u00e9rtelmezett algoritmusokat k\u00fcld, m\u00edg ha a hoszt kulcs m\u00e1r szerepel a gyors\u00edt\u00f3t\u00e1rban, a kapcsol\u00f3d\u00f3 algoritmust els\u0151 helyre \u00e1ll\u00edtj\u00e1k (az algoritmusokat a preferenciat\u00edpusok szerint rendezik). <\/p>\n

A probl\u00e9ma az OpenSSH 5.7 \u00e9s 8.3 k\u00f6z\u00f6tti kiad\u00e1saiban, valamint a PuTTY 0.68 \u00e9s 0.73 k\u00f6z\u00f6tti verzi\u00f3kban jelentkezik. A probl\u00e9ma eliminates<\/a><\/noindex> a kiad\u00e1sban PuTTY 0.74<\/a><\/noindex> a hoszt kulcs algoritmusok list\u00e1j\u00e1nak dinamikus fel\u00e9p\u00edt\u00e9se helyett egy \u00e1lland\u00f3 sorrendben val\u00f3 felsorol\u00e1s letilt\u00e1s\u00e1ra szolg\u00e1l\u00f3 opci\u00f3 hozz\u00e1ad\u00e1s\u00e1val.<\/p>\n

Az OpenSSH projekt nem tervezi megv\u00e1ltoztatni az SSH-kliens viselked\u00e9s\u00e9t, mivel ha az algoritmus megad\u00e1sa n\u00e9lk\u00fcl adjuk meg a kulcsot az els\u0151 helyen, akkor megpr\u00f3b\u00e1lunk egy nem megfelel\u0151en cache-elt kulcs algoritmus\u00e1nak alkalmaz\u00e1s\u00e1t, \u00e9s figyelmeztet\u00e9s jelenik meg az ismeretlen kulcsr\u00f3l. Vagyis a d\u00f6nt\u00e9s ott \u00e1ll \u2014 vagy inform\u00e1ci\u00f3sziv\u00e1rg\u00e1s (OpenSSH \u00e9s PuTTY), vagy kulcsv\u00e1lt\u00e1sr\u00f3l sz\u00f3l\u00f3 figyelmeztet\u00e9sek megjelen\u00edt\u00e9se (Dropbear SSH) abban az esetben, ha a mentett kulcs nem felel meg az alap\u00e9rtelmezett lista els\u0151 algoritmus\u00e1nak.<\/p>\n

Az OpenSSH biztons\u00e1ga \u00e9rdek\u00e9ben javasolt alternat\u00edv m\u00f3dszereket haszn\u00e1lni a gazda kulcs\u00e1nak ellen\u0151rz\u00e9s\u00e9re az SSHFP DNSSEC feljegyz\u00e9sekkel \u00e9s gazda tan\u00fas\u00edtv\u00e1nyokkal (PKI). A gazda kulcs algoritmusok adapt\u00edv kiv\u00e1laszt\u00e1s\u00e1t a HostKeyAlgorithms opci\u00f3val is le lehet tiltani, \u00e9s az UpdateHostKeys opci\u00f3val a kliens tov\u00e1bbi gazda kulcsokat kaphat az azonos\u00edt\u00e1s ut\u00e1n.<\/p>\n

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

Forr\u00e1s: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 SSH-\u043a\u043b\u0438\u0435\u043d\u0442\u0430\u0445 OpenSSH \u0438 PuTTY \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2020-14002 \u0432 PuTTY \u0438 CVE-2020-14145 \u0432 OpenSSH), \u043f\u0440\u0438\u0432\u043e\u0434\u044f\u0449\u0430\u044f \u043a \u0443\u0442\u0435\u0447\u043a\u0435 \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u0439 \u0432 \u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c\u0435 \u0441\u043e\u0433\u043b\u0430\u0441\u043e\u0432\u0430\u043d\u0438\u044f \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u044f. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u0430\u0442\u0430\u043a\u0443\u044e\u0449\u0435\u043c\u0443, \u0441\u043f\u043e\u0441\u043e\u0431\u043d\u043e\u043c\u0443 \u043f\u0435\u0440\u0435\u0445\u0432\u0430\u0442\u0438\u0442\u044c \u0442\u0440\u0430\u0444\u0438\u043a \u043a\u043b\u0438\u0435\u043d\u0442\u0430 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\u043f\u0440\u043e\u043a\u044d\u0448\u0438\u0440\u043e\u0432\u0430\u043d \u043a\u043b\u044e\u0447 \u0445\u043e\u0441\u0442\u0430. \u0417\u043d\u0430\u044f, \u0447\u0442\u043e […]<\/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-87197","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\udd47Sebezhet\u0151s\u00e9g az OpenSSH \u00e9s PuTTY SSH-kliens\u00e9ben | ProHoster","description":"OpenSSH \u00e9s PuTTY SSH-kliensekben","canonical_url":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-ssh-klientah-openssh-i-putty","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"hu_HU","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 SSH-\u043a\u043b\u0438\u0435\u043d\u0442\u0430\u0445 OpenSSH \u0438 PuTTY | ProHoster","og:description":"\u0412 SSH-\u043a\u043b\u0438\u0435\u043d\u0442\u0430\u0445 OpenSSH \u0438 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