{"id":172665,"date":"2026-05-19T00:24:34","date_gmt":"2026-05-18T22:24:34","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/dirtydecrypt-ocherednaya-uyazvimost-klassa-copy-fail-predostavlyayushhaya-prava-root-v-linux"},"modified":"2026-05-19T00:24:34","modified_gmt":"2026-05-18T22:24:34","slug":"dirtydecrypt-ocherednaya-uyazvimost-klassa-copy-fail-predostavlyayushhaya-prava-root-v-linux","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/dirtydecrypt-ocherednaya-uyazvimost-klassa-copy-fail-predostavlyayushhaya-prava-root-v-linux","title":{"rendered":"DirtyDecrypt \u2014 dal\u0161\u00ed zranitelnost t\u0159\u00eddy Copy Fail, poskytuj\u00edc\u00ed pr\u00e1va root v Linuxu","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Byla odhalena zranitelnost v j\u00e1dru Linux, kter\u00e1 umo\u017e\u0148uje neprivilegovan\u00e9mu u\u017eivateli z\u00edskat pr\u00e1va root, podobn\u011b jako zranitelnosti Copy Fail, Dirty Frag a Fragnesia, p\u0159episov\u00e1n\u00edm dat ve str\u00e1nkov\u00e9m cache. Zranitelnosti bylo p\u0159id\u011bleno k\u00f3dov\u00e9 jm\u00e9no DirtyDecrypt (probl\u00e9m je tak\u00e9 zm\u00edn\u011bn pod n\u00e1zvem DirtyCBC). Prototyp exploitace je k dispozici. <\/p>\n

CVE identifik\u00e1tor v pozn\u00e1mk\u00e1ch k exploitaci nen\u00ed zm\u00edn\u011bn, je uvedeno pouze, \u017ee v\u00fdzkumn\u00edci odhalili probl\u00e9m 9. kv\u011btna, po \u010dem\u017e to ozn\u00e1mili v\u00fdvoj\u00e1\u0159\u016fm j\u00e1dra, kte\u0159\u00ed odpov\u011bd\u011bli, \u017ee jejich n\u00e1lez duplikuje jinou zpr\u00e1vu o ji\u017e opraven\u00e9 zranitelnosti. Vzhledem k tomu, \u017ee patch byl ji\u017e za\u010dlen\u011bn do j\u00e1dra, se v\u00fdzkumn\u00edci rozhodli publikovat sv\u016fj navr\u017een\u00fd exploit. Podle popisu v exploitu se pou\u017e\u00edv\u00e1 zranitelnost CVE-2026-31635, jej\u00ed\u017e oprava byla p\u0159ijata do j\u00e1dra v dubnu a byla sou\u010d\u00e1st\u00ed v\u011btve 7.0.0 a verze 6.18.23, kter\u00e1 byla vyd\u00e1na 18. dubna. Probl\u00e9m se projevuje od j\u00e1dra 6.16. <\/p>\n

Stejn\u011b jako v p\u0159\u00edpad\u011b s\u00e9rie zranitelnost\u00ed Dirty Frag, nov\u00e1 zranitelnost se nach\u00e1z\u00ed ve ovlada\u010di RxRPC, kter\u00fd implementuje rodinu socket\u016f AF_RXRPC a stejn\u00fd RPC protokol, funguj\u00edc\u00ed nad UDP. Probl\u00e9m je zp\u016fsoben chybou p\u0159i kontrole velikosti dat ve funkci rxgk_verify_response() \u2014 m\u00edsto kontroly \"if (auth_len > len)\" bylo v k\u00f3du uvedeno \"if (auth_len < len)", co\u017e vedlo k p\u0159ed\u00e1n\u00ed dat do funkce rxgk_decrypt_skb() s velikost\u00ed v\u011bt\u0161\u00ed ne\u017e je povoleno. P\u0159i prov\u00e1d\u011bn\u00ed funkce rxgk_decrypt_skb() se de\u0161ifrov\u00e1n\u00ed dat prov\u00e1d\u011blo s nastaven\u00edm zm\u011bn p\u0159\u00edmo do str\u00e1nkov\u00e9ho cache, aby se vylou\u010dilo zbyte\u010dn\u00e9 bufferov\u00e1n\u00ed. Chybn\u00e9 ov\u011b\u0159en\u00ed velikosti vedlo k mo\u017enosti p\u0159eps\u00e1n\u00ed dat ve str\u00e1nkov\u00e9m cache na vybran\u00e9 offsetu. <\/p>\n

Exploatace zranitelnosti spo\u010d\u00edv\u00e1 ve \u010dten\u00ed souboru programu se suid root flagem (pro jeho ulo\u017een\u00ed do str\u00e1nkov\u00e9ho cache) a nahrazen\u00ed \u010d\u00e1sti k\u00f3du programu v str\u00e1nkov\u00e9m cache k\u00f3dem, kter\u00fd spou\u0161t\u00ed \/usr\/bin\/sh. N\u00e1sledn\u00e9 spu\u0161t\u011bn\u00ed programu zp\u016fsob\u00ed, \u017ee do pam\u011bti bude na\u010dtena nikoliv p\u016fvodn\u00ed spustiteln\u00e1 verze z \u00falo\u017ei\u0161t\u011b, ale pozm\u011bn\u011bn\u00e1 kopie ze str\u00e1nkov\u00e9ho cache. Jako suid programy v exploit\u011b je zahrnuta mo\u017enost pou\u017eit\u00ed \"\/usr\/bin\/su\", \"\/bin\/su\", \"\/usr\/bin\/mount\", \"\/usr\/bin\/passwd\" a \"\/usr\/bin\/chsh\". <\/p>\n

Pro vyu\u017eit\u00ed zranitelnosti mus\u00ed b\u00fdt p\u0159i sestaven\u00ed j\u00e1dra aktivn\u00ed mo\u017enost CONFIG_RXGK a pro automatick\u00e9 na\u010dten\u00ed mus\u00ed b\u00fdt k dispozici j\u00e1dro modulu rxrpc.ko (v n\u011bkter\u00fdch syst\u00e9mech se nezkompiluje). Stav odstran\u011bn\u00ed zranitelnost\u00ed v distribuc\u00edch lze posoudit na t\u011bchto str\u00e1nk\u00e1ch: Debian, Ubuntu, SUSE\/openSUSE, RHEL, Arch, Fedora. Jako obranou metodou ochrany lze zablokovat na\u010d\u00edt\u00e1n\u00ed modulu j\u00e1dra rxrpc: <\/p>\n

sh -c \"printf 'install rxrpc \/bin\/false\\n' > \/etc\/modprobe.d\/dirtydecrypt.conf; rmmod rxrpc 2>\/dev\/null; true\" <\/p>\n

D\u00e1le lze poznamenat, \u017ee byla zve\u0159ejn\u011bna v mailing listu v\u00fdvoj\u00e1\u0159\u016f j\u00e1dra Linux patch, kter\u00fd zcela zakazuje optimalizace v crypto API (AF_ALG), kter\u00e9 vyu\u017e\u00edvaj\u00ed p\u0159\u00edm\u00fd p\u0159\u00edstup k str\u00e1nkov\u00e9mu cache p\u0159i de\u0161ifrov\u00e1n\u00ed s pou\u017eit\u00edm algoritm\u016f \"skcipher\" a \"aead\". Optimalizace vylu\u010duj\u00ed zbyte\u010dn\u00e9 bufferov\u00e1n\u00ed dat, ale vytv\u00e1\u0159ej\u00ed rizika vzniku v\u00e1\u017en\u00fdch zranitelnost\u00ed. P\u0159edpokl\u00e1d\u00e1 se, \u017ee jejich deaktivace povede pouze k m\u00edrn\u00e9mu poklesu v\u00fdkonu z d\u016fvodu vzniku dal\u0161\u00ed operace kop\u00edrov\u00e1n\u00ed do samostatn\u00e9ho bufferu. Patche byly p\u0159ijaty spr\u00e1vcem subsyst\u00e9mu crypto API a zahrnuty do vetvy \"cryptodev\", ve kter\u00e9 se rozv\u00edjej\u00ed mo\u017enosti pro p\u0159ed\u00e1n\u00ed do hlavn\u00ed v\u011btve budouc\u00edch vyd\u00e1n\u00ed j\u00e1dra Linux.
\n
Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u044f\u0434\u0440\u0435 Linux \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043f\u043e \u0430\u043d\u0430\u043b\u043e\u0433\u0438\u0438 \u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044f\u043c\u0438 Copy Fail, Dirty Frag \u0438 Fragnesia \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u043f\u0440\u0430\u0432\u0430 root, \u043f\u0435\u0440\u0435\u0437\u0430\u043f\u0438\u0441\u0430\u0432 \u0434\u0430\u043d\u043d\u044b\u0435 \u0432 \u0441\u0442\u0440\u0430\u043d\u0438\u0447\u043d\u043e\u043c \u043a\u044d\u0448\u0435. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043f\u0440\u0438\u0441\u0432\u043e\u0435\u043d\u043e \u043a\u043e\u0434\u043e\u0432\u043e\u0435 \u0438\u043c\u044f DirtyDecrypt (\u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0442\u0430\u043a\u0436\u0435 \u0443\u043f\u043e\u043c\u0438\u043d\u0430\u0435\u0442\u0441\u044f \u043f\u043e\u0434 \u0438\u043c\u0435\u043d\u0435\u043c DirtyCBC). \u0414\u043e\u0441\u0442\u0443\u043f\u0435\u043d \u043f\u0440\u043e\u0442\u043e\u0442\u0438\u043f \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430. CVE-\u0438\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440 \u0432 \u043f\u0440\u0438\u043c\u0435\u0447\u0430\u043d\u0438\u0438 \u043a \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0443 \u043d\u0435 \u0443\u043f\u043e\u043c\u0438\u043d\u0430\u0435\u0442\u0441\u044f, \u0443\u043a\u0430\u0437\u0430\u043d\u043e \u043b\u0438\u0448\u044c, \u0447\u0442\u043e \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0438 \u0432\u044b\u044f\u0432\u0438\u043b\u0438 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0443 9 \u043c\u0430\u044f, […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-172665","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\udd47DirtyDecrypt \u2014 dal\u0161\u00ed zranitelnost t\u0159\u00eddy Copy Fail, poskytuj\u00edc\u00ed pr\u00e1va roota v Linuxu | ProHoster","description":"V j\u00e1dru Linux byla odhalena zranitelnost, kter\u00e1 analogicky k zranitelnostem Copy Fail, Dirty Frag a Fragnesia, umo\u017e\u0148uje nep\u0159ihl\u00e1\u0161en\u00e9mu u\u017eivateli z\u00edskat pr\u00e1va roota p\u0159eps\u00e1n\u00edm dat v str\u00e1nkov\u00e9m 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ProHoster","og:description":"\u0412 \u044f\u0434\u0440\u0435 Linux \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c, \u043f\u043e \u0430\u043d\u0430\u043b\u043e\u0433\u0438\u0438 \u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044f\u043c\u0438 Copy Fail, Dirty Frag \u0438 Fragnesia \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0435\u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u043f\u0440\u0430\u0432\u0430 root, \u043f\u0435\u0440\u0435\u0437\u0430\u043f\u0438\u0441\u0430\u0432 \u0434\u0430\u043d\u043d\u044b\u0435 \u0432 \u0441\u0442\u0440\u0430\u043d\u0438\u0447\u043d\u043e\u043c \u043a\u044d\u0448\u0435.","og:url":"https:\/\/prohoster.info\/cs\/blog\/news\/dirtydecrypt-ocherednaya-uyazvimost-klassa-copy-fail-predostavlyayushhaya-prava-root-v-linux","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":"2026-05-18T22:24:34+00:00","article:modified_time":"2026-05-18T22:24:34+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\/172665","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\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/comments?post=172665"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/172665\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=172665"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=172665"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=172665"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}