{"id":116883,"date":"2024-07-01T18:05:44","date_gmt":"2024-07-01T16:05:44","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-openssh-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root-na-serverah-s-glibc"},"modified":"2024-07-01T18:05:44","modified_gmt":"2024-07-01T16:05:44","slug":"uyazvimost-v-openssh-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root-na-serverah-s-glibc","status":"publish","type":"post","link":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-openssh-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root-na-serverah-s-glibc","title":{"rendered":"Sebezhet\u0151s\u00e9g az OpenSSH-ban, amely lehet\u0151v\u00e9 teszi a t\u00e1voli k\u00f3dv\u00e9grehajt\u00e1st root jogosults\u00e1gokkal a Glibc-val rendelkez\u0151 szervereken","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A Qualys felfedezett egy kritikus sebezhet\u0151s\u00e9get (CVE-2024-6387) az OpenSSH-ban, amely lehet\u0151v\u00e9 teszi a t\u00e1voli k\u00f3dv\u00e9grehajt\u00e1st root jogosults\u00e1gokkal, hiteles\u00edt\u00e9s megker\u00fcl\u00e9s\u00e9vel. A 'regreSSHion' k\u00f3dn\u00e9vvel illetett sebezhet\u0151s\u00e9g az OpenSSH 8.5-\u00f6s verzi\u00f3j\u00e1t\u00f3l kezd\u0151d\u0151en, alap\u00e9rtelmezett konfigur\u00e1ci\u00f3ban jelentkezik Glibc standard k\u00f6nyvt\u00e1rral rendelkez\u0151 rendszereken. <\/p>\n

A t\u00e1mad\u00e1s lehet\u0151s\u00e9g\u00e9t egy 32 bites Glibc-szel rendelkez\u0151 rendszeren, ASLR (c\u00edmter\u00fclet v\u00e9letlen\u00edt\u00e9s) v\u00e9delemmel demonstr\u00e1lt\u00e1k. A laborat\u00f3riumi k\u00f6r\u00fclm\u00e9nyek k\u00f6z\u00f6tt a t\u00e1mad\u00e1s sikeres megval\u00f3s\u00edt\u00e1s\u00e1hoz 6-8 \u00f3r\u00e1s folyamatos kapcsol\u00f3d\u00e1s volt sz\u00fcks\u00e9ges a sshd konfigur\u00e1ci\u00f3 maxim\u00e1lis intenzit\u00e1s\u00e1val. szerverrel<\/a> A t\u00e1mad\u00e1s lefolytat\u00e1sa egyszer\u0171bb, \u00e9s kevesebb id\u0151t ig\u00e9nyel az ASLR n\u00e9lk\u00fcli rendszereken, vagy olyan disztrib\u00faci\u00f3kban, amelyek m\u00f3dos\u00edtott OpenSSH-t haszn\u00e1lnak, ahol le van tiltva az ASLR \u00fajra v\u00e9letlen\u00edt\u00e9se minden egyes kapcsolatra. A sebezhet\u0151s\u00e9g mindenhol t\u00f6rt\u00e9n\u0151 orvosl\u00e1s\u00e1ig nem ker\u00fcl nyilv\u00e1noss\u00e1gra a munkacsoport protot\u00edpusa, de el\u00e9rhet\u0151 egy el\u00e9g r\u00e9szletes le\u00edr\u00e1s a sebezhet\u0151s\u00e9gr\u0151l, amely lehet\u0151v\u00e9 teszi harmadik f\u00e9l exploitjainak megjelen\u00e9s\u00e9t.<\/p>\n

Nem z\u00e1rhat\u00f3 ki a t\u00e1mad\u00e1s lehet\u0151s\u00e9ge 64 bites rendszereken sem, de az ilyen rendszerekhez m\u0171k\u00f6d\u0151 exploittal jelenleg nem rendelkez\u00fcnk. Felt\u00e9telezhet\u0151, hogy a t\u00e1mad\u00e1s v\u00e9grehajt\u00e1sa 64 bites rendszereken sokkal t\u00f6bb id\u0151t vesz ig\u00e9nybe, de nem haladhatja meg az egy hetet. Az OpenSSH az OpenBSD-ben nem \u00e9rintett, ugyanis ezen a rendszeren 2001 \u00f3ta alkalmaznak egy v\u00e9delmi mechanizmust, amely blokkolja az ilyen t\u00edpus\u00fa t\u00e1mad\u00e1sokat. M\u00e1s, a Glibc-t\u00f3l elt\u00e9r\u0151 standard k\u00f6nyvt\u00e1rakat haszn\u00e1l\u00f3 rendszereken elm\u00e9letileg lehets\u00e9ges a m\u00f3dszer alkalmaz\u00e1s\u00e1nak adapt\u00e1l\u00e1sa a t\u00e1mad\u00e1s v\u00e9grehajt\u00e1s\u00e1hoz (ezzel a k\u00e9rd\u00e9ssel a Qualys eddig nem foglalkozott). <\/p>\n

A sebezhet\u0151s\u00e9get a ma megjelent OpenSSH 9.8 (jav\u00edt\u00e1s) kiad\u00e1sban orvosolt\u00e1k. A csomagfriss\u00edt\u00e9sek nyomon k\u00f6vet\u00e9s\u00e9t a disztrib\u00faci\u00f3k oldalain lehet elv\u00e9gezni: Debian, Ubuntu, RHEL, SUSE\/openSUSE, Fedora, ROSA, Gentoo, ALT Linux, Arch \u00e9s FreeBSD. A sebezhet\u0151s\u00e9g blokkol\u00e1s\u00e1nak megker\u00fcl\u00e9s\u00e9re az sshd_config-ban a param\u00e9tert \"LoginGraceTime=0\" lehet be\u00e1ll\u00edtani, azonban a v\u00e1rakoz\u00e1si id\u0151 kikapcsol\u00e1sa megk\u00f6nny\u00edti a szolg\u00e1ltat\u00e1smegtagad\u00e1s kezdem\u00e9nyez\u00e9s\u00e9t, ha t\u00fal sok kapcsolatot pr\u00f3b\u00e1lnak l\u00e9trehozni, amelyek meghaladj\u00e1k a MaxStartups param\u00e9ter \u00e1ltal megadott hat\u00e1rokat.
\nA t\u00e1mad\u00e1si k\u00eds\u00e9rletek egyik jele a napl\u00f3ban megjelen\u0151 nagy sz\u00e1m\u00fa \"Timeout before authentication\" bejegyz\u00e9s.<\/p>\n

A s\u00e9r\u00fcl\u00e9kenys\u00e9g egy regressz\u00edv v\u00e1ltoz\u00e1s k\u00f6vetkezm\u00e9nyek\u00e9nt alakult ki, amely az OpenSSH 8.5 verzi\u00f3 r\u00e9sz\u00e9t k\u00e9pezte, \u00e9s versenyhelyzetet okoz a sshd jelz\u00e9skezel\u0151 k\u00f3dj\u00e1ban. A regresszi\u00f3 a r\u00e9gi CVE-2006-5051 s\u00e9r\u00fcl\u00e9kenys\u00e9g elleni v\u00e9delmet megsz\u00fcntette, amely a 4.4-es verzi\u00f3 el\u0151tt (2006) jelentkezett, \u00e9s elm\u00e9leti jelleg\u0171 volt.
\nAz OpenSSH 8.5 fejleszt\u00e9se sor\u00e1n t\u00e9vesen elt\u00e1vol\u00edtott\u00e1k a sigdie() f\u00fcggv\u00e9nyb\u0151l a \"#ifdef DO_LOG_SAFE_IN_SIGHAND\" blokkot, amely k\u00f6zvetlen\u00fcl a SIGALRM kezel\u0151b\u0151l h\u00edv\u00f3dik meg.<\/p>\n

A SIGALRM kezel\u0151je az sshd-ben aszinkron m\u00f3don h\u00edv\u00f3dik meg, ha a kliens nem hajtotta v\u00e9gre az azonos\u00edt\u00e1st a csatlakoz\u00e1si id\u0151keret alatt (LoginGraceTime, alap\u00e9rtelmez\u00e9s szerint 120 m\u00e1sodperc). A t\u00e1mad\u00e1s arra \u00e9p\u00edt, hogy a jelz\u0151k kezel\u0151je aszinkron jelkezel\u00e9s mellett nem biztons\u00e1gos f\u00fcggv\u00e9nyeket h\u00edv, mint p\u00e9ld\u00e1ul a syslog(). A syslog() f\u00fcggv\u00e9ny a Glibc-ban nem alkalmas aszinkron jelkezel\u0151 f\u00fcggv\u00e9nyekben val\u00f3 haszn\u00e1latra, mivel malloc() \u00e9s free() f\u00fcggv\u00e9nyeket h\u00edv. A SIGALRM jelz\u00e9s aktiv\u00e1l\u00e1sa, amely megszak\u00edtja egy adott k\u00f3d m\u0171k\u00f6d\u00e9s\u00e9t az sshd-ben, \u00e1llapotmegs\u00e9rt\u00e9shez vezethet, \u00e9s a kihaszn\u00e1l\u00e1s c\u00e9lja a megfelel\u0151 k\u00f3d megszak\u00edt\u00e1s\u00e1nak felt\u00e9teleinek megteremt\u00e9se a sz\u00fcks\u00e9ges v\u00e9grehajt\u00e1si id\u0151pontban. A s\u00e9r\u00fcl\u00e9kenys\u00e9g nem \u00e9rinti az OpenBSD-t, mivel ott a syslog() helyett a SIGALRM jelz\u00e9skezel\u0151b\u0151l a syslog_r() f\u00fcggv\u00e9ny h\u00edv\u00f3dik meg, amelyet kifejezetten aszinkron v\u00e9grehajt\u00e1sra terveztek.
\n
Forr\u00e1s: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Qualys \u0432\u044b\u044f\u0432\u0438\u043b\u0430 \u043a\u0440\u0438\u0442\u0438\u0447\u0435\u0441\u043a\u0443\u044e \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2024-6387) \u0432 OpenSSH, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0443\u044e \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e\u0433\u043e \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u043a\u043e\u0434\u0430 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root \u0431\u0435\u0437 \u043f\u0440\u043e\u0445\u043e\u0436\u0434\u0435\u043d\u0438\u044f \u0430\u0443\u0442\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u0438. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043a\u043e\u0442\u043e\u0440\u0430\u044f \u043f\u043e\u043b\u0443\u0447\u0438\u043b\u0430 \u043a\u043e\u0434\u043e\u0432\u043e\u0435 \u0438\u043c\u044f regreSSHion, \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0432 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u0438 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e \u043d\u0430\u0447\u0438\u043d\u0430\u044f \u0441 \u0432\u0435\u0440\u0441\u0438\u0438 OpenSSH 8.5 \u043d\u0430 \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u0445 \u0441\u043e \u0441\u0442\u0430\u043d\u0434\u0430\u0440\u0442\u043d\u043e\u0439 \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u043e\u0439 Glibc. \u0412\u043e\u0437\u043c\u043e\u0436\u043d\u043e\u0441\u0442\u044c \u0441\u043e\u0432\u0435\u0440\u0448\u0435\u043d\u0438\u044f \u0430\u0442\u0430\u043a\u0438 \u043f\u0440\u043e\u0434\u0435\u043c\u043e\u043d\u0441\u0442\u0440\u0438\u0440\u043e\u0432\u0430\u043d\u0430 \u043d\u0430 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u0441 Glibc \u0441 \u0432\u043a\u043b\u044e\u0447\u0451\u043d\u043d\u043e\u0439 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 ASLR (\u0440\u0430\u043d\u0434\u043e\u043c\u0438\u0437\u0430\u0446\u0438\u044f […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-116883","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\udd47S\u00e9r\u00fcl\u00e9kenys\u00e9g az OpenSSH-ban, amely lehet\u0151v\u00e9 teszi a Glibc-vel rendelkez\u0151 szervereken a t\u00e1voli k\u00f3d root jogokkal t\u00f6rt\u00e9n\u0151 v\u00e9grehajt\u00e1s\u00e1t | ProHoster","description":"A Qualys v\u00e1llalat kritikus s\u00e9r\u00fcl\u00e9kenys\u00e9get (CVE-2024-6387) fedezett fel az OpenSSH-ban, amely lehet\u0151v\u00e9 teszi a t\u00e1voli k\u00f3dv\u00e9grehajt\u00e1st root jogokkal an\u00e9lk\u00fcl, hogy autentik\u00e1ci\u00f3n kellene \u00e1tesni.","canonical_url":"https:\/\/prohoster.info\/hu\/blog\/news\/uyazvimost-v-openssh-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root-na-serverah-s-glibc","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 OpenSSH, 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