{"id":110745,"date":"2023-10-11T21:10:17","date_gmt":"2023-10-11T19:10:17","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/perepolnenie-bufera-v-curl-i-libcurl-proyavlyayushheesya-pri-obrashhenii-cherez-socks5-proksi"},"modified":"2023-10-11T21:10:17","modified_gmt":"2023-10-11T19:10:17","slug":"perepolnenie-bufera-v-curl-i-libcurl-proyavlyayushheesya-pri-obrashhenii-cherez-socks5-proksi","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/perepolnenie-bufera-v-curl-i-libcurl-proyavlyayushheesya-pri-obrashhenii-cherez-socks5-proksi","title":{"rendered":"Buffer overflow i curl og libcurl, der opst\u00e5r ved adgang via SOCKS5-proxy.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

I v\u00e6rkt\u00f8jet til at hente og sende data over nettet, curl, samt i den tilh\u00f8rende bibliotek libcurl, er der opdaget en s\u00e5rbarhed (CVE-2023-38545), der kan f\u00f8re til buffer overflow og potentielt muligg\u00f8re udf\u00f8relse af angriberens kode p\u00e5 klientsiden, n\u00e5r der oprettes forbindelse til en HTTPS-server kontrolleret af en skadelig akt\u00f8r. Problemet opst\u00e5r kun, n\u00e5r curl har adgang gennem en SOCKS5-proxy. Ved direkte adgang uden proxy opst\u00e5r s\u00e5rbarheden ikke. S\u00e5rbarheden er blevet rettet i curl version 8.4.0. Forskeren, der afsl\u00f8rede fejlen, modtog en bel\u00f8nning p\u00e5 $4660 gennem Internet Bug Bounty-initiativet p\u00e5 Hackerone. <\/p>\n

S\u00e5rbarheden skyldes en fejl i koden til oplysning af hostnavn f\u00f8r anmodning til SOCKS5-proxy. Hvis hostnavnet er op til 256 tegn langt, sender curl straks navnet til SOCKS5-proxyen for opl\u00f8sning p\u00e5 dens side. Er navnet l\u00e6ngere end 255 tegn, skifter den til en lokal resolver og sender allerede den bestemte adresse til SOCKS5. P\u00e5 grund af en fejl i koden kunne flaget, der angiver behovet for lokal opl\u00f8sning, under en langsom forbindelse gennem SOCKS5 v\u00e6re sat til den forkerte v\u00e6rdi, hvilket f\u00f8rte til, at det lange hostnavn blev skrevet i bufferet, der var allokeret til at gemme IP-adresser<\/a> eller et navn, der ikke overstiger 255 tegn. <\/p>\n

Webstedsejeren, som cURL henvender sig til gennem en SOCKS5-proxy, kan initiere en buffer overflow p\u00e5 klientsiden ved at returnere en omdirigeringskode (HTTP 30x) og angive en 'Location:' header med en URL, der har et dom\u00e6nenavn, hvis st\u00f8rrelse ligger mellem 16 og 64 KB (16 KB er det minimale st\u00f8rrelse, der kr\u00e6ves for at overskride den tildelte buffer, mens 65 KB er relateret til den maksimalt tilladte l\u00e6ngde for dom\u00e6nenavne i en URL). Hvis omdirigering af foresp\u00f8rgsler er tilladt i libcurl\u2019s indstillinger, og den anvendte SOCKS5-proxy er tilstr\u00e6kkeligt langsom, vil det lange dom\u00e6nenavn blive skrevet ind i en lille buffer, der er mindre i st\u00f8rrelse. <\/p>\n

S\u00e5rbarheden p\u00e5virker prim\u00e6rt applikationer baseret p\u00e5 libcurl og manifesterer sig i curl-v\u00e6rkt\u00f8jet kun n\u00e5r der bruges optionen '--limit-rate' med en v\u00e6rdi mindre end 65541 \u2014 standardbufferst\u00f8rrelsen i libcurl er 16 KB, og i curl-v\u00e6rkt\u00f8jet er den 100 KB, men denne st\u00f8rrelse \u00e6ndres afh\u00e6ngigt af v\u00e6rdien af parameteren '--limit-rate'. <\/p>\n

Daniel Stenberg, projektets forfatter, n\u00e6vnte, at s\u00e5rbarheden forblev uopdaget i 1315 dage. Det blev ogs\u00e5 sagt, at 41% af de tidligere identificerede s\u00e5rbarheder i curl sandsynligvis kunne v\u00e6re undg\u00e5et, hvis curl var skrevet i et sprog, der sikrer sikker h\u00e5ndtering af hukommelse, men der er ikke planer om at omskrive curl til et andet sprog i den n\u00e6rmeste fremtid. Som sikkerhedsforanstaltninger foresl\u00e5s det at udvide v\u00e6rkt\u00f8jsparken til kodetestning og mere aktivt bruge afh\u00e6ngigheder skrevet p\u00e5 programmeringssprog, der sikrer sikker hukommelsesh\u00e5ndtering. Der overvejes ogs\u00e5 en trinvis udskiftning af dele af curl med versioner skrevet i sikre sprog, s\u00e5som den eksperimentelle HTTP-backend Hyper, implementeret i Rust.
\n
Kilde: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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\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\udd47Bufferoverl\u00f8b i curl og libcurl, der viser sig ved henvendelse over SOCKS5-proxy | ProHoster","description":"I v\u00e6rkt\u00f8jet til at hente og sende data over netv\u00e6rket curl og den samtidigt udviklende bibliotekt libcurl er der identificeret en s\u00e5rbarhed (CVE-2023-38545), som kan f\u00f8re til bufferoverl\u00f8b og potentielt til udf\u00f8relse.","canonical_url":"https:\/\/prohoster.info\/da\/blog\/news\/perepolnenie-bufera-v-curl-i-libcurl-proyavlyayushheesya-pri-obrashhenii-cherez-socks5-proksi","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"da_DK","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\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 \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 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