{"id":112310,"date":"2023-12-19T03:10:31","date_gmt":"2023-12-19T01:10:31","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/reliz-openssh-9-6-c-ustraneniem-uyazvimostej"},"modified":"2023-12-19T03:10:31","modified_gmt":"2023-12-19T01:10:31","slug":"reliz-openssh-9-6-c-ustraneniem-uyazvimostej","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/reliz-openssh-9-6-c-ustraneniem-uyazvimostej","title":{"rendered":"Vyd\u00e1n\u00ed OpenSSH 9.6 s odstran\u011bn\u00edm zranitelnost\u00ed","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Bylo vyd\u00e1no OpenSSH 9.6, otev\u0159en\u00e9 implementace klienta a serveru pro pr\u00e1ci s protokoly SSH 2.0 a SFTP. V nov\u00e9 verzi bylo odstran\u011bno t\u0159i bezpe\u010dnostn\u00ed nedostatky:     <\/p>\n<ul>\n<li class=\"l\"> Zranitelnost v protokolu SSH (CVE-2023-48795, \u00fatok \u201eTerrapin\u201c), kter\u00e1 umo\u017e\u0148uje b\u011bhem MITM \u00fatoku p\u0159epnout spojen\u00ed na m\u00e9n\u011b zabezpe\u010den\u00e9 algoritmy autentizace a vypnout ochranu proti \u00fatok\u016fm prost\u0159ednictv\u00edm extern\u00edch kan\u00e1l\u016f, kter\u00e9 reprodukuj\u00ed vstup pomoc\u00ed anal\u00fdzy zpo\u017ed\u011bn\u00ed mezi stisknut\u00edm kl\u00e1ves na kl\u00e1vesnici. Metoda \u00fatoku je podrobn\u011b pops\u00e1na v samostatn\u00e9 zpr\u00e1v\u011b.\n<li class=\"l\"> Zranitelnost v utilit\u011b ssh, kter\u00e1 umo\u017e\u0148uje prov\u00e1d\u011bt substituci libovoln\u00fdch shellov\u00fdch p\u0159\u00edkaz\u016f prost\u0159ednictv\u00edm manipulace s hodnotami p\u0159ihla\u0161ovac\u00edho jm\u00e9na a hostitele obsahuj\u00edc\u00edmi speci\u00e1ln\u00ed znaky. Zranitelnost m\u016f\u017ee b\u00fdt zneu\u017eita, pokud \u00fato\u010dn\u00edk ovl\u00e1d\u00e1 hodnoty p\u0159ihla\u0161ovac\u00edho jm\u00e9na a jm\u00e9na hostitele p\u0159ed\u00e1van\u00e9 v ssh, direktivy ProxyCommand a LocalCommand nebo bloky \u201ematch exec\u201c, ve kter\u00fdch jsou uvedeny znaky substituce, jako %u a %h. Nap\u0159\u00edklad nespr\u00e1vn\u00e9 p\u0159ihla\u0161ovac\u00ed jm\u00e9no a hostitel mohou b\u00fdt pou\u017eity v syst\u00e9mech vyu\u017e\u00edvaj\u00edc\u00edch submoduly v Git, proto\u017ee Git nezakazuje pou\u017eit\u00ed speci\u00e1ln\u00edch znak\u016f v n\u00e1zvu hostitele a u\u017eivatelsk\u00e9m jm\u00e9nu. Podobn\u00e1 zranitelnost se tak\u00e9 projevuje v libssh.\n<li class=\"l\"> Chyba v ssh-agentu, kv\u016fli kter\u00e9 se p\u0159i p\u0159id\u00e1v\u00e1n\u00ed soukrom\u00fdch kl\u00ed\u010d\u016f PKCS#11 uplat\u0148ovala omezen\u00ed pouze na prvn\u00ed kl\u00ed\u010d, kter\u00fd token PKCS#11 vr\u00e1til. Probl\u00e9m se net\u00fdk\u00e1 b\u011b\u017en\u00fdch soukrom\u00fdch kl\u00ed\u010d\u016f, token\u016f FIDO a kl\u00ed\u010d\u016f, kter\u00e9 jsou zad\u00e1ny bez omezen\u00ed.  <\/ul>\n<p>Dal\u0161\u00ed zm\u011bny:   <\/p>\n<ul>\n<li class=\"l\"> V ssh byla p\u0159id\u00e1na substituce \u201e%j\u201c, kter\u00e1 je rozvinuta na n\u00e1zev hostitele uveden\u00fd prost\u0159ednictv\u00edm direktivy ProxyJump.\n<li class=\"l\"> Do ssh byla p\u0159id\u00e1na podpora nastaven\u00ed ChannelTimeout na stran\u011b klienta, kter\u00e1 m\u016f\u017ee b\u00fdt pou\u017eita k ukon\u010den\u00ed neaktivn\u00edch kan\u00e1l\u016f.\n<li class=\"l\"> Do ssh, sshd, ssh-add a ssh-keygen byla p\u0159id\u00e1na podpora pro \u010dten\u00ed soukrom\u00fdch kl\u00ed\u010d\u016f ED25519 ve form\u00e1tu PEM PKCS8 (d\u0159\u00edve byl podporov\u00e1n pouze form\u00e1t OpenSSH).\n<li class=\"l\"> V ssh a sshd byla p\u0159id\u00e1na roz\u0161\u00ed\u0159en\u00ed protokolu pro op\u011btovn\u00e9 vyjedn\u00e1n\u00ed algoritm\u016f digit\u00e1ln\u00edho podpisu pro autentizaci pomoc\u00ed ve\u0159ejn\u00fdch kl\u00ed\u010d\u016f, kter\u00e9 se prov\u00e1d\u00ed v etap\u011b po obdr\u017een\u00ed \u00fadaj\u016f o u\u017eivatelsk\u00e9m jm\u00e9nu. Nap\u0159\u00edklad pomoc\u00ed roz\u0161\u00ed\u0159en\u00ed lze selektivn\u011b pou\u017e\u00edvat jin\u00e9 algoritmy v\u00e1zan\u00e9 na u\u017eivatele prost\u0159ednictv\u00edm uveden\u00ed PubkeyAcceptedAlgorithms v bloku \u201eMatch user\u201c.\n<li class=\"l\"> V ssh-add a ssh-agent bylo p\u0159id\u00e1no roz\u0161\u00ed\u0159en\u00ed protokolu pro nastaven\u00ed certifik\u00e1t\u016f p\u0159i na\u010d\u00edt\u00e1n\u00ed kl\u00ed\u010d\u016f PKCS#11, co\u017e umo\u017e\u0148uje pou\u017e\u00edvat certifik\u00e1ty spojen\u00e9 s priv\u00e1tn\u00edmi kl\u00ed\u010di PKCS#11 ve v\u0161ech utilit\u00e1ch OpenSSH, kter\u00e9 podporuj\u00ed ssh-agent, a ne pouze v ssh.\n<li class=\"l\"> Bylo vylep\u0161eno rozpozn\u00e1v\u00e1n\u00ed nepodporovan\u00fdch nebo nestabiln\u00edch p\u0159ep\u00edna\u010d\u016f p\u0159eklada\u010de, jako je \u201e-fzero-call-used-regs\u201c v clang.\n<li class=\"l\"> Pro omezen\u00ed privilegi\u00ed procesu sshd v verz\u00edch OpenSolaris, kter\u00e9 podporuj\u00ed rozhran\u00ed getpflags(), byl pou\u017eit re\u017eim PRIV_XPOLICY m\u00edsto PRIV_LIMIT.      <\/ul>\n<p>Zdroj: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=60305\">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 9.6, \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\u044b \u0442\u0440\u0438 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b \u0441 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u044c\u044e: \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0432 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0435 SSH (CVE-2023-48795, \u0430\u0442\u0430\u043a\u0430 &#171;Terrapin&#187;), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0432 \u0445\u043e\u0434\u0435 MITM-\u0430\u0442\u0430\u043a\u0438 \u043e\u0442\u043a\u0430\u0442\u0438\u0442\u044c \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435 \u043d\u0430 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u043c\u0435\u043d\u0435\u0435 \u0437\u0430\u0449\u0438\u0449\u0451\u043d\u043d\u044b\u0445 \u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c\u043e\u0432 \u0430\u0443\u0442\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u0438 \u0438 \u043e\u0442\u043a\u043b\u044e\u0447\u0438\u0442\u044c \u0437\u0430\u0449\u0438\u0442\u0443 \u043e\u0442 \u0430\u0442\u0430\u043a \u043f\u043e \u0441\u0442\u043e\u0440\u043e\u043d\u043d\u0438\u043c \u043a\u0430\u043d\u0430\u043b\u0430\u043c, \u0432\u043e\u0441\u0441\u043e\u0437\u0434\u0430\u044e\u0449\u0438\u043c \u0432\u0432\u043e\u0434 \u0447\u0435\u0440\u0435\u0437 [&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-112310","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d \u0440\u0435\u043b\u0438\u0437 OpenSSH 9.6, \u043e\u0442\u043a\u0440\u044b\u0442\u043e\u0439 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