{"id":111506,"date":"2023-11-14T21:10:14","date_gmt":"2023-11-14T19:10:14","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/vossozdanie-rsa-klyuchej-cherez-analiz-ssh-soedinenij-k-sbojnym-serveram"},"modified":"2023-11-14T21:10:14","modified_gmt":"2023-11-14T19:10:14","slug":"vossozdanie-rsa-klyuchej-cherez-analiz-ssh-soedinenij-k-sbojnym-serveram","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/vossozdanie-rsa-klyuchej-cherez-analiz-ssh-soedinenij-k-sbojnym-serveram","title":{"rendered":"RSA-kulcsok \u00fajragy\u00e1rt\u00e1sa SSH-kapcsolatok elemz\u00e9s\u00e9vel meghib\u00e1sodott szerverekhez","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A kutat\u00f3csoport a Kaliforniai Egyetem San Diego-i kampusz\u00e1n bemutatta az SSH-szerverek titkos\u00edtott RSA-kulcsainak vissza\u00e1ll\u00edt\u00e1s\u00e1nak lehet\u0151s\u00e9g\u00e9t az SSH-forgalom passz\u00edv elemz\u00e9se \u00fatj\u00e1n. A t\u00e1mad\u00e1s olyan szerverek ellen hajthat\u00f3 v\u00e9gre, ahol k\u00f6r\u00fclm\u00e9nyek vagy a t\u00e1mad\u00f3 cselekedetei k\u00f6vetkezt\u00e9ben hib\u00e1k l\u00e9pnek fel a digit\u00e1lis al\u00e1\u00edr\u00e1s kisz\u00e1m\u00edt\u00e1sa sor\u00e1n SSH-kapcsolat l\u00e9tes\u00edt\u00e9sekor. A hib\u00e1k sz\u00e1rmazhatnak szoftveres probl\u00e9m\u00e1kb\u00f3l (nem megfelel\u0151 matematikai m\u0171veletek v\u00e9grehajt\u00e1sa, mem\u00f3riahiba) vagy hardveres hib\u00e1kb\u00f3l (hib\u00e1k az NVRAM \u00e9s DRAM m\u0171k\u00f6d\u00e9s\u00e9ben vagy \u00e1ramkimarad\u00e1sok sor\u00e1n). <\/p>\n

A hib\u00e1k el\u0151id\u00e9z\u00e9s\u00e9nek egyik lehet\u0151s\u00e9ge a RowHammer-t\u00edpus\u00fa t\u00e1mad\u00e1sok, amelyek lehet\u0151v\u00e9 teszik a mem\u00f3ria egyes bitjeinek tartalm\u00e1nak torz\u00edt\u00e1s\u00e1t t\u00e1volr\u00f3l vagy JavaScript-k\u00f3d b\u00f6ng\u00e9sz\u0151ben t\u00f6rt\u00e9n\u0151 feldolgoz\u00e1sa sor\u00e1n, intenz\u00edv ciklikus adatolvas\u00e1s mellett szomsz\u00e9dos mem\u00f3riasejtekb\u0151l. Egy m\u00e1sik hibaokoz\u00e1si lehet\u0151s\u00e9g a sebezhet\u0151s\u00e9gek kihaszn\u00e1l\u00e1sa, amelyek verem t\u00falcsordul\u00e1shoz \u00e9s a mem\u00f3ria kulcsainak adatinak megs\u00e9rt\u00e9s\u00e9hez vezethetnek. <\/p>\n

A publik\u00e1lt kutat\u00e1s kimutatta, hogy az SSH-ban alkalmazott RSA-alap\u00fa digit\u00e1lis al\u00e1\u00edr\u00e1sok eset\u00e9n a digit\u00e1lis al\u00e1\u00edr\u00e1s param\u00e9terei felett elm\u00e9leti t\u00e1mad\u00e1sok v\u00e9gezhet\u0151k a z\u00e1rt RSA-kulcsok Lattice m\u00f3dszerrel val\u00f3 vissza\u00e1ll\u00edt\u00e1s\u00e1ra (Hiba T\u00e1mad\u00e1s), ha szoftveres vagy hardveres hib\u00e1k l\u00e9pnek fel az al\u00e1\u00edr\u00e1s kisz\u00e1m\u00edt\u00e1sa sor\u00e1n. A m\u00f3dszer l\u00e9nyege, hogy a helyes \u00e9s a hib\u00e1s RSA-digit\u00e1lis al\u00e1\u00edr\u00e1sok \u00f6sszehasonl\u00edt\u00e1s\u00e1val meghat\u00e1rozhat\u00f3 a kulcsgener\u00e1l\u00e1s sor\u00e1n felhaszn\u00e1lt egyik pr\u00edmsz\u00e1m legnagyobb k\u00f6z\u00f6s oszt\u00f3ja. <\/p>\n

Az RSA titkos\u00edt\u00e1sa egy nagy sz\u00e1m modulos hatv\u00e1nyra emel\u00e9s\u00e9n alapul. A nyilv\u00e1nos kulcs tartalmazza a modult \u00e9s a hatv\u00e1nyt. A modul k\u00e9t v\u00e9letlenszer\u0171 pr\u00edmsz\u00e1mb\u00f3l k\u00e9pz\u0151dik, amelyek csak a z\u00e1rt kulcs tulajdonosa sz\u00e1m\u00e1ra ismertek. A t\u00e1mad\u00e1s alkalmazhat\u00f3 az RSA megval\u00f3s\u00edt\u00e1saira, amelyek a K\u00ednai marad\u00e9koszt\u00e1lyt \u00e9s a meghat\u00e1rozott padl\u00f3szab\u00e1lyoz\u00f3 s\u00e9m\u00e1kat (p\u00e9ld\u00e1ul PKCS#1 v1.5) haszn\u00e1lj\u00e1k. <\/p>\n

Egy t\u00e1mad\u00e1s v\u00e9grehajt\u00e1s\u00e1hoz elegend\u0151 a legit\u00edm SSH-szerverekhez val\u00f3 passz\u00edv kapcsolatok nyomon k\u00f6vet\u00e9se, am\u00edg fel nem fedeznek egy hib\u00e1s digit\u00e1lis al\u00e1\u00edr\u00e1st a forgalomban, amit inform\u00e1ci\u00f3forr\u00e1sk\u00e9nt lehet felhaszn\u00e1lni a z\u00e1rt RSA kulcs \u00fajraalkot\u00e1s\u00e1ra. Az \u00fajraalkotott hoszt RSA kulccsal a t\u00e1mad\u00f3 egy MITM-t\u00e1mad\u00e1s sor\u00e1n \u00e9szrev\u00e9tlen\u00fcl \u00e1tir\u00e1ny\u00edthatja a k\u00e9r\u00e9seket egy hamis hosztra, amely mag\u00e1t a kompromitt\u00e1lt SSH-szervernek \u00e1lc\u00e1zza, \u00e9s megszervezheti az azon tov\u00e1bb\u00edtott adatok lehallgat\u00e1s\u00e1t. szerver<\/a> adatok. <\/p>\n

A kik\u00e9mlelt h\u00e1l\u00f3zati adatok k\u00f6r\u00fclbel\u00fcl 5,2 milli\u00e1rd rekordj\u00e1nak tanulm\u00e1nyoz\u00e1sa sor\u00e1n a kutat\u00f3k k\u00f6r\u00fclbel\u00fcl 3,2 milli\u00e1rd ny\u00edlt hosztkulcsot \u00e9s digit\u00e1lis al\u00e1\u00edr\u00e1st azonos\u00edtottak, amelyek az SSH munkamenet egyeztet\u00e9se sor\u00e1n ker\u00fcltek felhaszn\u00e1l\u00e1sra. Ezek k\u00f6z\u00fcl 1,2 milli\u00e1rd (39,1%) RSA algoritmus seg\u00edts\u00e9g\u00e9vel k\u00e9sz\u00fclt. 593671 esetben (0,048%) az RSA-al\u00e1\u00edr\u00e1s s\u00e9r\u00fclt volt, \u00e9s nem ment \u00e1t az ellen\u0151rz\u00e9sen. 4962 hib\u00e1s al\u00e1\u00edr\u00e1s eset\u00e9n a Lattice faktoriz\u00e1l\u00f3 m\u00f3dszert siker\u00fclt alkalmazni a z\u00e1rt kulcs meghat\u00e1roz\u00e1s\u00e1ra a megismert ny\u00edlt kulcs alapj\u00e1n, ami v\u00e9g\u00fcl 189 egyedi RSA kulcsp\u00e1r \u00fajb\u00f3li el\u0151\u00e1ll\u00edt\u00e1s\u00e1hoz vezetett (sok esetben az ugyanazokat a kulcsokat \u00e9s hib\u00e1s eszk\u00f6z\u00f6ket haszn\u00e1lt\u00e1k k\u00fcl\u00f6nb\u00f6z\u0151 s\u00e9r\u00fclt al\u00e1\u00edr\u00e1sok gener\u00e1l\u00e1s\u00e1ra). A kulcsok \u00fajraalkot\u00e1s\u00e1hoz k\u00f6r\u00fclbel\u00fcl 26 \u00f3r\u00e1nyi processzorteljes\u00edtm\u00e9ny sz\u00fcks\u00e9geltetett.

\"RSA-kulcsok<\/center> <\/p>\n

A probl\u00e9ma kiz\u00e1r\u00f3lag a specifikus SSH protokollmegval\u00f3s\u00edt\u00e1sokat \u00e9rinti, amelyeket els\u0151sorban be\u00e1gyazott eszk\u00f6z\u00f6kben haszn\u00e1lnak. A probl\u00e9m\u00e1s SSH megval\u00f3s\u00edt\u00e1sok p\u00e9ld\u00e1jak\u00e9nt eml\u00edt\u00e9st nyertek a Zyxel, Cisco, Mocana \u00e9s Hillstone Networks term\u00e9kek. Az OpenSSH nem \u00e9rintett a probl\u00e9m\u00e1ban, mivel kulcsgener\u00e1l\u00e1skor az OpenSSL (vagy LibreSSL) k\u00f6nyvt\u00e1rat haszn\u00e1lja, amely a hibaanal\u00edzis alap\u00fa t\u00e1mad\u00e1sok ellen 2001 \u00f3ta v\u00e9delmet ny\u00fajt. Tov\u00e1bb\u00e1, az OpenSSH ssh-rsa digit\u00e1lis al\u00e1\u00edr\u00e1si s\u00e9ma (sha1 alap\u00fa) 2020 \u00f3ta elavultnak van nyilv\u00e1n\u00edtva, \u00e9s a 8.8-as verzi\u00f3val le van tiltva (a rsa-sha2-256 \u00e9s rsa-sha2-512 s\u00e9m\u00e1k t\u00e1mogat\u00e1sa megmarad). Potenci\u00e1lisan a t\u00e1mad\u00e1s az IPsec protokollra is alkalmazhat\u00f3 lehet, de a kutat\u00f3knak nem volt elegend\u0151 k\u00eds\u00e9rleti adata a t\u00e1mad\u00e1s gyakorlati meger\u0151s\u00edt\u00e9s\u00e9re.
\n
Forr\u00e1s: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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[…]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":111507,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-111506","post","type-post","status-publish","format-standard","has-post-thumbnail","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\udd47RSA-kulcsok \u00fajragener\u00e1l\u00e1sa a cs\u00f6kkentett szerverekhez val\u00f3 SSH-kapcsolatok elemz\u00e9s\u00e9vel | ProHoster","description":"A Kaliforniai Egyetem san dieg\u00f3i kutat\u00f3csoportja bemutatta, hogy lehets\u00e9ges az SSH-szerver z\u00e1rt hoszt RSA kulcsainak \u00fajraalkot\u00e1sa a SSH forgalom passz\u00edv 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\u0442\u0440\u0430\u0444\u0438\u043a\u0430 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