{"id":117137,"date":"2024-07-09T15:43:01","date_gmt":"2024-07-09T13:43:01","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-paketah-s-openssh-iz-sostava-rhel-9-dopuskayushhaya-udalyonnoe-vypolnenie-koda"},"modified":"2024-07-09T15:43:01","modified_gmt":"2024-07-09T13:43:01","slug":"uyazvimost-v-paketah-s-openssh-iz-sostava-rhel-9-dopuskayushhaya-udalyonnoe-vypolnenie-koda","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-paketah-s-openssh-iz-sostava-rhel-9-dopuskayushhaya-udalyonnoe-vypolnenie-koda","title":{"rendered":"Zranitelnost v bal\u00ed\u010dc\u00edch OpenSSH obsa\u017een\u00fdch v RHEL 9, umo\u017e\u0148uj\u00edc\u00ed vzd\u00e1len\u00e9 spu\u0161t\u011bn\u00ed k\u00f3du.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V procesu zkoum\u00e1n\u00ed ned\u00e1vno nalezen\u00e9 kritick\u00e9 zranitelnosti v OpenSSH byla objevena dal\u0161\u00ed podobn\u00e1 zranitelnost (CVE-2024-6409), kter\u00e1 umo\u017e\u0148uje vzd\u00e1len\u00e9 vykon\u00e1n\u00ed k\u00f3du bez ov\u011b\u0159en\u00ed. Nov\u00e1 zranitelnost nen\u00ed tak nebezpe\u010dn\u00e1 jako ta p\u0159edchoz\u00ed, proto\u017ee se projevuje po sn\u00ed\u017een\u00ed privilegi\u00ed v spu\u0161t\u011bn\u00e9m podprocesu SSH serveru. Zranitelnost se nach\u00e1z\u00ed v bal\u00ed\u010dc\u00edch openssh z distribuce Red Hat Enterprise Linux 9, zalo\u017een\u00fdch na publikovan\u00e9 verzi OpenSSH 8.7 z roku 2021. Probl\u00e9m se tak\u00e9 t\u00fdk\u00e1 bal\u00ed\u010dk\u016f pro Fedora Linux 36 a 37, kter\u00e9 jsou zalo\u017eeny na verz\u00edch OpenSSH 8.7 a 8.8. <\/p>\n

Z podstaty je zranitelnost podobn\u00e1 p\u0159edchoz\u00edmu probl\u00e9mu a je tak\u00e9 zp\u016fsobena stavem z\u00e1vodu v obslu\u017en\u00e9 rutin\u011b p\u0159eru\u0161en\u00ed SIGALRM, kter\u00fd vznik\u00e1 z prov\u00e1d\u011bn\u00ed funkc\u00ed, kter\u00e9 nejsou navr\u017eeny pro vyvol\u00e1n\u00ed v asynchronn\u00edm re\u017eimu z obslu\u017en\u00fdch rutin sign\u00e1l\u016f. Obslu\u017en\u00e1 rutina se aktivuje p\u0159i vypr\u0161en\u00ed \u010dasov\u00e9ho limitu ur\u010den\u00e9ho pomoc\u00ed parametru LoginGraceTime a p\u0159eru\u0161uje aktu\u00e1ln\u00ed vykon\u00e1v\u00e1n\u00ed k\u00f3du. Pou\u017eit\u00ed v obslu\u017en\u00e9 rutin\u011b p\u0159eru\u0161en\u00ed nenavr\u017een\u00fdch pro asynchronn\u00ed vykon\u00e1v\u00e1n\u00ed funkc\u00ed, v nich\u017e se pou\u017e\u00edv\u00e1 dynamick\u00e1 alokace pam\u011bti, jako je syslog(), m\u016f\u017ee v\u00e9st k po\u0161kozen\u00ed vnit\u0159n\u00edch struktur malloc p\u0159i vyvol\u00e1n\u00ed SIGALRM b\u011bhem vykon\u00e1v\u00e1n\u00ed ur\u010dit\u00e9ho k\u00f3du. <\/p>\n

Nov\u00e1 zranitelnost se li\u0161\u00ed t\u00edm, \u017ee stav z\u00e1vodu nast\u00e1v\u00e1 z d\u016fvodu vyvol\u00e1n\u00ed funkce cleanup_exit() v obslu\u017en\u00e9 rutin\u011b sign\u00e1lu grace_alarm_handler(). V hlavn\u00edm k\u00f3du OpenSSH m\u016f\u017ee b\u00fdt tato funkce pou\u017eita v asynchronn\u011b vykon\u00e1van\u00e9m k\u00f3du, ale v bal\u00ed\u010dc\u00edch pro RHEL 9 a Fedora byl pou\u017eit dodate\u010dn\u00fd patch, kter\u00fd do cleanup_exit() p\u0159id\u00e1v\u00e1 vol\u00e1n\u00ed funkce pro generov\u00e1n\u00ed ud\u00e1lost\u00ed auditu, navr\u017een\u00e9 k pou\u017eit\u00ed v obslu\u017en\u00fdch rutin\u00e1ch sign\u00e1l\u016f. <\/p>\n

Tento patch byl pou\u017eit v RHEL 9 a odvozen\u00fdch distribuc\u00edch v bal\u00ed\u010dc\u00edch zalo\u017een\u00fdch na OpenSSH 8.7p1. Ve sou\u010dasn\u00fdch verz\u00edch Fedory se probl\u00e9m neprojevuje, proto\u017ee od Fedory 38 p\u0159e\u0161el syst\u00e9m na nov\u011bj\u0161\u00ed verzi OpenSSH bez zm\u011bny cleanup_exit(). Na rozd\u00edl od p\u0159edchoz\u00ed zranitelnosti neexistuje pro blokaci nov\u00e9ho probl\u00e9mu obran\u00fd zp\u016fsob, kter\u00fd by vych\u00e1zel z pou\u017eit\u00ed volby «-e» v sshd, co\u017e zakazuje v\u00fdstup logu p\u0159es syslog. P\u0159esto v\u0161ak pro blokaci zranitelnosti v sshd_config lze nastavit parametr «LoginGraceTime=0».
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Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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\u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430 Red Hat Enterprise Linux 9, […]<\/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-117137","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\udd47Zranitelnost v bal\u00edc\u00edch OpenSSH v r\u00e1mci RHEL 9, kter\u00e1 umo\u017e\u0148uje vzd\u00e1len\u00e9 spu\u0161t\u011bn\u00ed k\u00f3du | ProHoster","description":"B\u011bhem zkoum\u00e1n\u00ed kritick\u00e9 zranitelnosti v OpenSSH odhalen\u00e9 minul\u00fd t\u00fdden byla objevena dal\u0161\u00ed podobn\u00e1 zranitelnost (CVE-2024-6409), kter\u00e1 umo\u017e\u0148uje dosa\u017een\u00ed vzd\u00e1len\u00e9ho spu\u0161t\u011bn\u00ed k\u00f3du bez ov\u011b\u0159en\u00ed.","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-paketah-s-openssh-iz-sostava-rhel-9-dopuskayushhaya-udalyonnoe-vypolnenie-koda","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"cs_CZ","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 \u043f\u0430\u043a\u0435\u0442\u0430\u0445 \u0441 OpenSSH \u0438\u0437 \u0441\u043e\u0441\u0442\u0430\u0432\u0430 RHEL 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