V n\u00e1stroji pro p\u0159\u00edjem a odes\u00edl\u00e1n\u00ed dat p\u0159es s\u00ed\u0165 curl a v paraleln\u011b se vyv\u00edjej\u00edc\u00ed knihovn\u011b libcurl byla zji\u0161t\u011bna zranitelnost (CVE-2023-38545), kter\u00e1 m\u016f\u017ee v\u00e9st k p\u0159ete\u010den\u00ed vyrovn\u00e1vac\u00ed pam\u011bti a potenci\u00e1ln\u011b k proveden\u00ed k\u00f3du \u00fato\u010dn\u00edka na stran\u011b klienta, kdy\u017e se n\u00e1stroj curl nebo aplikace pou\u017e\u00edvaj\u00edc\u00ed libcurl pokus\u00ed p\u0159ipojit k HTTPS serveru pod kontrolou \u00fato\u010dn\u00edka. Probl\u00e9m se projevuje pouze p\u0159i aktivovan\u00e9m p\u0159\u00edstupu p\u0159es SOCKS5 proxy. P\u0159i p\u0159\u00edm\u00e9m p\u0159\u00edstupu bez proxy se zranitelnost neprojevuje. Zranitelnost byla odstran\u011bna ve verzi curl 8.4.0. Bezpe\u010dnostn\u00ed v\u00fdzkumn\u00edk, kter\u00fd chybu objevil, obdr\u017eel odm\u011bnu ve v\u00fd\u0161i 4660 $ v r\u00e1mci iniciativy Internet Bug Bounty na Hackerone. <\/p>\n
Zranitelnost je zp\u016fsobena chybou v k\u00f3du p\u0159i \u0159e\u0161en\u00ed n\u00e1zvu hostitele p\u0159ed p\u0159ipojen\u00edm k SOCKS5 proxy. P\u0159i d\u00e9lce n\u00e1zvu hostitele do 256 znak\u016f curl okam\u017eit\u011b p\u0159ed\u00e1 n\u00e1zev SOCKS5 proxy k \u0159e\u0161en\u00ed na jej\u00ed stran\u011b, zat\u00edmco pokud je n\u00e1zev del\u0161\u00ed ne\u017e 255 znak\u016f, p\u0159epne na m\u00edstn\u00ed resolver a p\u0159ed\u00e1 SOCKS5 ji\u017e ur\u010denou adresu. V d\u016fsledku chyby v k\u00f3du mohl b\u00fdt flag ozna\u010duj\u00edc\u00ed pot\u0159ebu m\u00edstn\u00edho \u0159e\u0161en\u00ed ve f\u00e1zi pomal\u00e9ho vyjedn\u00e1v\u00e1n\u00ed spojen\u00ed p\u0159es SOCKS5 nastaven na nespr\u00e1vnou hodnotu, co\u017e vedlo k z\u00e1pisu dlouh\u00e9ho n\u00e1zvu hostitele do vyrovn\u00e1vac\u00ed pam\u011bti ur\u010den\u00e9 pro uchov\u00e1n\u00ed IP adres<\/a> nebo n\u00e1zvu, kter\u00fd nep\u0159esahuje 255 znak\u016f. <\/p>\n Vlastn\u00edk webov\u00e9 str\u00e1nky, na kterou se curl obrac\u00ed p\u0159es SOCKS5 proxy, m\u016f\u017ee iniciovat p\u0159ete\u010den\u00ed z\u00e1sobn\u00edku na stran\u011b klienta t\u00edm, \u017ee vr\u00e1t\u00ed v odpov\u011bdi k\u00f3d p\u0159esm\u011brov\u00e1n\u00ed dotazu (HTTP 30x) a nastav\u00ed v hlavi\u010dce «Location:» URL s n\u00e1zvem hostitele, jeho\u017e velikost se pohybuje od 16 do 64 KB (hodnota 16 KB je d\u00e1na minim\u00e1ln\u00ed velikost\u00ed pot\u0159ebnou pro p\u0159ete\u010den\u00ed vyhrazen\u00e9ho z\u00e1sobn\u00edku, zat\u00edmco hodnota 65 KB souvis\u00ed s maxim\u00e1ln\u011b povolenou d\u00e9lkou n\u00e1zvu hostitele v URL). Pokud jsou v nastaven\u00ed libcurl povolena p\u0159esm\u011brov\u00e1n\u00ed a pou\u017eit\u00e1 SOCKS5 proxy je dostate\u010dn\u011b pomal\u00e1, bude dlouh\u00fd n\u00e1zev hostitele zaps\u00e1n do mal\u00e9ho z\u00e1sobn\u00edku, kter\u00fd je z\u00e1m\u011brn\u011b men\u0161\u00ed. <\/p>\n Zranitelnost se p\u0159ev\u00e1\u017en\u011b dot\u00fdk\u00e1 aplikac\u00ed zalo\u017een\u00fdch na libcurl a projevuje se v utilit\u011b curl pouze p\u0159i pou\u017eit\u00ed volby «—limit-rate» s hodnotou men\u0161\u00ed ne\u017e 65541 — ve libcurl je ve v\u00fdchoz\u00edm nastaven\u00ed vyhrazen z\u00e1sobn\u00edk o velikosti 16 KB, zat\u00edmco v utilit\u011b curl je to 100 KB, av\u0161ak tato velikost se m\u011bn\u00ed v z\u00e1vislosti na hodnot\u011b parametru «—limit-rate». <\/p>\n Daniel Stenberg, autor projektu, zm\u00ednil, \u017ee zranitelnost z\u016fst\u00e1vala nepov\u0161imnuta po dobu 1315 dn\u00ed. Tak\u00e9 bylo uvedeno, \u017ee 41 % d\u0159\u00edve zji\u0161t\u011bn\u00fdch zranitelnost\u00ed v curl by pravd\u011bpodobn\u011b bylo mo\u017en\u00e9 se vyhnout, pokud by byl curl naps\u00e1n v jazyce, kter\u00fd zaji\u0161\u0165uje bezpe\u010dn\u00e9 pr\u00e1ce s pam\u011bt\u00ed, ale p\u0159eps\u00e1n\u00ed curl do jin\u00e9ho jazyka se v bl\u00edzk\u00e9 budoucnosti nepl\u00e1nuje. Jako opat\u0159en\u00ed pro zv\u00fd\u0161en\u00ed bezpe\u010dnosti k\u00f3du se navrhuje roz\u0161\u00ed\u0159it n\u00e1stroje pro testov\u00e1n\u00ed k\u00f3du a aktivn\u011bji pou\u017e\u00edvat z\u00e1vislosti napsan\u00e9 v programovac\u00edch jazyc\u00edch, kter\u00e9 zaji\u0161\u0165uj\u00ed bezpe\u010dn\u00e9 pr\u00e1ce s pam\u011bt\u00ed. Tak\u00e9 se zva\u017euje mo\u017enost postupn\u00e9 v\u00fdm\u011bny \u010d\u00e1st\u00ed curl za varianty napsan\u00e9 v bezpe\u010dn\u00fdch jazyc\u00edch, jako je experiment\u00e1ln\u00ed HTTP backend Hyper, realizovan\u00fd v jazyce Rust. \u0412 \u0443\u0442\u0438\u043b\u0438\u0442\u0435 \u0434\u043b\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f \u0438 \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0438 \u0434\u0430\u043d\u043d\u044b\u0445 \u043f\u043e \u0441\u0435\u0442\u0438 curl \u0438 \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u044e\u0449\u0435\u0439\u0441\u044f \u043f\u0430\u0440\u0430\u043b\u043b\u0435\u043b\u044c\u043d\u043e \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0435 libcurl \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2023-38545), \u043a\u043e\u0442\u043e\u0440\u0430\u044f \u043c\u043e\u0436\u0435\u0442 \u043f\u0440\u0438\u0432\u0435\u0441\u0442\u0438 \u043a \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u0431\u0443\u0444\u0435\u0440\u0430 \u0438 \u043f\u043e\u0442\u0435\u043d\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043a \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u043a\u043e\u0434\u0430 \u0430\u0442\u0430\u043a\u0443\u044e\u0449\u0435\u0433\u043e \u043d\u0430 \u0441\u0442\u043e\u0440\u043e\u043d\u0435 \u043a\u043b\u0438\u0435\u043d\u0442\u0430 \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0449\u0435\u043d\u0438\u0438 \u043f\u0440\u0438 \u043f\u043e\u043c\u043e\u0449\u0438 \u0443\u0442\u0438\u043b\u0438\u0442\u044b curl \u0438\u043b\u0438 \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u044f, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044e\u0449\u0435\u0433\u043e libcurl, \u043a HTTPS-\u0441\u0435\u0440\u0432\u0435\u0440\u0443, \u043f\u043e\u0434\u043a\u043e\u043d\u0442\u0440\u043e\u043b\u044c\u043d\u043e\u043c\u0443 \u0437\u043b\u043e\u0443\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u0438\u043a\u0443. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0442\u043e\u043b\u044c\u043a\u043e \u0432 \u0441\u043b\u0443\u0447\u0430\u0435 \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u044f \u0432 curl […]<\/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-110745","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\udd47P\u0159ete\u010den\u00ed vyrovn\u00e1vac\u00ed pam\u011bti v curl a libcurl, 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\u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u041f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0431\u0443\u0444\u0435\u0440\u0430 \u0432 curl \u0438 libcurl, \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u044e\u0449\u0435\u0435\u0441\u044f \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0449\u0435\u043d\u0438\u0438 \u0447\u0435\u0440\u0435\u0437 SOCKS5-\u043f\u0440\u043e\u043a\u0441\u0438 | ProHoster","og:description":"\u0412 \u0443\u0442\u0438\u043b\u0438\u0442\u0435 \u0434\u043b\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f \u0438 \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0438 \u0434\u0430\u043d\u043d\u044b\u0445 \u043f\u043e \u0441\u0435\u0442\u0438 curl \u0438 \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u044e\u0449\u0435\u0439\u0441\u044f \u043f\u0430\u0440\u0430\u043b\u043b\u0435\u043b\u044c\u043d\u043e \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0435 libcurl 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Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"