{"id":106630,"date":"2023-02-03T12:48:25","date_gmt":"2023-02-03T10:48:25","guid":{"rendered":"https:\/\/prohoster.info\/?p=106630"},"modified":"2023-02-03T21:50:37","modified_gmt":"2023-02-03T19:50:37","slug":"vypusk-openssh-9-2-s-ustraneniem-uyazvimosti-proyavlyayushhejsya-na-etape-do-autentifikaczii","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/vypusk-openssh-9-2-s-ustraneniem-uyazvimosti-proyavlyayushhejsya-na-etape-do-autentifikaczii","title":{"rendered":"Vyd\u00e1n\u00ed OpenSSH 9.2 s odstran\u011bn\u00edm zranitelnosti projevuj\u00edc\u00ed se p\u0159ed autentizac\u00ed","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Bylo zve\u0159ejn\u011bno vyd\u00e1n\u00ed OpenSSH 9.2, otev\u0159en\u00e9 implementace klienta a serveru pro pr\u00e1ci s protokoly SSH 2.0 a SFTP. V nov\u00e9 verzi byla odstran\u011bna zranitelnost, kter\u00e1 vede k dvoj\u00edmu uvoln\u011bn\u00ed pam\u011bti v f\u00e1zi p\u0159ed autentizac\u00ed. Zranitelnosti je vystaven pouze vyd\u00e1n\u00ed OpenSSH 9.1, v d\u0159\u00edv\u011bj\u0161\u00edch verz\u00edch se probl\u00e9m neprojevuje.       <\/p>\n<p>K vytvo\u0159en\u00ed podm\u00ednek pro zneu\u017eitelnost sta\u010d\u00ed zm\u011bnit banner SSH klienta na &#171;SSH-2.0-FuTTYSH_9.1p1&#187;, abychom aktivovali p\u0159\u00edznaky &#171;SSH_BUG_CURVE25519PAD&#187; a &#171;SSH_OLD_DHGEX&#187;, kter\u00e9 jsou z\u00e1visl\u00e9 na verzi SSH klienta. Po aktivaci t\u011bchto p\u0159\u00edznak\u016f je pam\u011b\u0165 pro buffer &#171;options.kex_algorithms&#187; uvoln\u011bna dvakr\u00e1t &#8212; p\u0159i vykon\u00e1n\u00ed funkce do_ssh2_kex(), kter\u00e1 vol\u00e1 compat_kex_proposal(), a p\u0159i vykon\u00e1n\u00ed funkce do_authentication2(), kter\u00e1 vol\u00e1 postupn\u011b input_userauth_request(), mm_getpwnamallow(), copy_set_server_options(), assemble_algorithms() a kex_assemble_names().    <\/p>\n<p>Vytvo\u0159en\u00ed funk\u010dn\u00edho exploit pro zneu\u017eitelnost se pova\u017euje za nepravd\u011bpodobn\u00e9, proto\u017ee proces zneu\u017eit\u00ed je p\u0159\u00edli\u0161 slo\u017eit\u00fd &#8212; modern\u00ed knihovny pro spr\u00e1vu pam\u011bti poskytuj\u00ed ochranu proti dvoj\u00edmu uvoln\u011bn\u00ed pam\u011bti a proces pre-auth, kter\u00fd obsahuje chybu, je prov\u00e1d\u011bn s omezen\u00fdmi opr\u00e1vn\u011bn\u00edmi v izolovan\u00e9m sandboxov\u00e9m prost\u0159ed\u00ed.    <\/p>\n<p>Krom\u011b uveden\u00e9 zranitelnosti byly v nov\u00e9m vyd\u00e1n\u00ed tak\u00e9 odstran\u011bny dal\u0161\u00ed dv\u011b bezpe\u010dnostn\u00ed probl\u00e9my:  <\/p>\n<ul>\n<li class=\"l\"> Chyba p\u0159i zpracov\u00e1n\u00ed nastaven\u00ed &#171;PermitRemoteOpen&#187;, kter\u00e1 vede k ignorov\u00e1n\u00ed prvn\u00edho argumentu, pokud se li\u0161\u00ed od hodnot &#171;any&#187; a &#171;none&#187;. Probl\u00e9m se objevuje ve verz\u00edch nov\u011bj\u0161\u00edch ne\u017e OpenSSH 8.7 a zp\u016fsobuje, \u017ee je p\u0159esko\u010dena kontrola p\u0159i specifikaci pouze jednoho opr\u00e1vn\u011bn\u00ed.\n<li class=\"l\"> \u00dato\u010dn\u00edk, kter\u00fd ovl\u00e1d\u00e1 DNS server pou\u017e\u00edvan\u00fd pro ur\u010dov\u00e1n\u00ed jmen, m\u016f\u017ee dos\u00e1hnout substituce speci\u00e1ln\u00edch znak\u016f (nap\u0159\u00edklad &#171;*&#187;) do soubor\u016f known_hosts, pokud jsou v konfiguraci aktivov\u00e1ny volby CanonicalizeHostname a CanonicalizePermittedCNAMEs a syst\u00e9mov\u00fd resolver nekontroluje spr\u00e1vnost odpov\u011bd\u00ed od DNS serveru. Prov\u00e1d\u011bn\u00ed \u00fatoku je pova\u017eov\u00e1no za nepravd\u011bpodobn\u00e9, proto\u017ee vracen\u00e9 n\u00e1zvy mus\u00ed spl\u0148ovat podm\u00ednky stanoven\u00e9 p\u0159es CanonicalizePermittedCNAMEs.    <\/ul>\n<p>Dal\u0161\u00ed zm\u011bny:  <\/p>\n<ul>\n<li class=\"l\"> Do ssh_config pro ssh byla p\u0159id\u00e1na volba EnableEscapeCommandline, kter\u00e1 \u0159\u00edd\u00ed zahrnut\u00ed zpracov\u00e1n\u00ed escape sekvence &#171;~C&#187; na klientsk\u00e9 stran\u011b, co\u017e poskytuje p\u0159\u00edkazov\u00fd \u0159\u00e1dek. Ve v\u00fdchoz\u00edm nastaven\u00ed je zpracov\u00e1n\u00ed &#171;~C&#187; nyn\u00ed vypnuto, aby se pou\u017eila p\u0159\u00edsn\u011bj\u0161\u00ed sandboxov\u00e1 izolace, co\u017e m\u016f\u017ee potenci\u00e1ln\u011b zp\u016fsobit poruchy syst\u00e9m\u016f, kde se &#171;~C&#187; pou\u017e\u00edv\u00e1 k p\u0159esm\u011brov\u00e1n\u00ed port\u016f b\u011bhem provozu.\n<li class=\"l\"> Do souboru sshd_config byla p\u0159id\u00e1na direktiva ChannelTimeout pro nastaven\u00ed \u010dasov\u00e9ho limitu neaktivity kan\u00e1lu (kan\u00e1ly, ve kter\u00fdch v uveden\u00e9m \u010dasov\u00e9m r\u00e1mci nebyl zaznamen\u00e1n \u017e\u00e1dn\u00fd provoz, budou automaticky uzav\u0159eny). Pro relaci, X11, agenta a p\u0159esm\u011brov\u00e1n\u00ed provozu mohou b\u00fdt nastaveny r\u016fzn\u00e9 \u010dasov\u00e9 limity.\n<li class=\"l\"> Do souboru sshd_config byla p\u0159id\u00e1na direktiva UnusedConnectionTimeout, kter\u00e1 umo\u017e\u0148uje nastavit \u010dasov\u00fd limit pro ukon\u010den\u00ed klientsk\u00fdch p\u0159ipojen\u00ed, kter\u00e1 jsou ur\u010ditou dobu bez aktivn\u00edch kan\u00e1l\u016f.\n<li class=\"l\"> Do sshd byla p\u0159id\u00e1na volba &#171;-V&#187; pro zobrazen\u00ed verze, podobn\u011b jako m\u00e1 tato volba v klientu ssh.\n<li class=\"l\"> Do v\u00fdstupu &#171;ssh -G&#187; byla p\u0159id\u00e1na \u0159\u00e1dka &#171;Host&#187;, kter\u00e1 odr\u00e1\u017e\u00ed hodnotu argumentu s n\u00e1zvem hostitele.\n<li class=\"l\"> Do protokol\u016f scp a sftp byla p\u0159id\u00e1na mo\u017enost &#171;-X&#187; pro spr\u00e1vu takov\u00fdch parametr\u016f protokolu SFTP, jako je velikost vyrovn\u00e1vac\u00ed pam\u011bti pro kop\u00edrov\u00e1n\u00ed a po\u010det \u010dekaj\u00edc\u00edch po\u017eadavk\u016f na dokon\u010den\u00ed.\n<li class=\"l\"> V ssh-keyscan je povoleno skenov\u00e1n\u00ed cel\u00fdch CIDR rozsah\u016f adres, nap\u0159\u00edklad &#171;ssh-keyscan 192.168.0.0\/24&#187;.      <\/ul>\n<p>Zdroj: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=58598\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d \u0440\u0435\u043b\u0438\u0437 OpenSSH 9.2, \u043e\u0442\u043a\u0440\u044b\u0442\u043e\u0439 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u043a\u043b\u0438\u0435\u043d\u0442\u0430 \u0438 \u0441\u0435\u0440\u0432\u0435\u0440\u0430 \u0434\u043b\u044f \u0440\u0430\u0431\u043e\u0442\u044b \u043f\u043e \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430\u043c SSH 2.0 \u0438 SFTP. \u0412 \u043d\u043e\u0432\u043e\u0439 \u0432\u0435\u0440\u0441\u0438\u0438 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043f\u0440\u0438\u0432\u043e\u0434\u044f\u0449\u0430\u044f \u043a \u0434\u0432\u043e\u0439\u043d\u043e\u043c\u0443 \u043e\u0441\u0432\u043e\u0431\u043e\u0436\u0434\u0435\u043d\u0438\u044e \u043e\u0431\u043b\u0430\u0441\u0442\u0438 \u043f\u0430\u043c\u044f\u0442\u0438 \u043d\u0430 \u0441\u0442\u0430\u0434\u0438\u0438 \u0434\u043e \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\u0438 \u043f\u043e\u0434\u0432\u0435\u0440\u0436\u0435\u043d \u0442\u043e\u043b\u044c\u043a\u043e \u0432\u044b\u043f\u0443\u0441\u043a OpenSSH 9.1, \u0432 \u0431\u043e\u043b\u0435\u0435 \u0440\u0430\u043d\u043d\u0438\u0445 \u0432\u0435\u0440\u0441\u0438\u044f\u0445 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043d\u0435 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f. \u0414\u043b\u044f \u0441\u043e\u0437\u0434\u0430\u043d\u0438\u044f \u0443\u0441\u043b\u043e\u0432\u0438\u0439 \u043f\u0440\u043e\u044f\u0432\u043b\u0435\u043d\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0434\u043e\u0441\u0442\u0430\u0442\u043e\u0447\u043d\u043e \u0438\u0437\u043c\u0435\u043d\u0438\u0442\u044c \u0431\u0430\u043d\u043d\u0435\u0440 SSH-\u043a\u043b\u0438\u0435\u043d\u0442\u0430 [&hellip;]<\/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-106630","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 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\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\u0412\u044b\u043f\u0443\u0441\u043a OpenSSH 9.2 \u0441 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0435\u043c \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438, \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u044e\u0449\u0435\u0439\u0441\u044f \u043d\u0430 \u044d\u0442\u0430\u043f\u0435 \u0434\u043e \u0430\u0443\u0442\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u0438 | ProHoster","og:description":"\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d \u0440\u0435\u043b\u0438\u0437 OpenSSH 9.2, \u043e\u0442\u043a\u0440\u044b\u0442\u043e\u0439 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u043a\u043b\u0438\u0435\u043d\u0442\u0430 \u0438 \u0441\u0435\u0440\u0432\u0435\u0440\u0430 \u0434\u043b\u044f \u0440\u0430\u0431\u043e\u0442\u044b \u043f\u043e \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430\u043c SSH 2.0 \u0438 SFTP.","og:url":"https:\/\/prohoster.info\/cs\/blog\/news\/vypusk-openssh-9-2-s-ustraneniem-uyazvimosti-proyavlyayushhejsya-na-etape-do-autentifikaczii","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2023-02-03T10:48:25+00:00","article:modified_time":"2023-02-03T19:50:37+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":[],"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/106630","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/comments?post=106630"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/106630\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=106630"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=106630"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=106630"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}