{"id":82556,"date":"2020-05-22T19:41:55","date_gmt":"2020-05-22T17:41:55","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc"},"modified":"2020-05-22T19:41:55","modified_gmt":"2020-05-22T17:41:55","slug":"kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/kriticheskaya-uyazvimost-v-realizaczii-funkczii-memcpy-dlya-armv7-iz-sostava-glibc","title":{"rendered":"Kritisk s\u00e5rbarhed i implementeringen af memcpy-funktionen for ARMv7 i Glibc","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Sikkerhedsforskere fra Cisco har afsl\u00f8ret<\/a><\/noindex> detaljer s\u00e5rbarheder<\/a><\/noindex> (CVE-2020-6096<\/a><\/noindex>) i implementeringen af memcpy()-funktionen, der tilbydes i Glibc for 32-bit ARMv7-platforme. Problemet skyldes forkert h\u00e5ndtering af negative v\u00e6rdier for parameteren, der angiver st\u00f8rrelsen af det kopierede omr\u00e5de, p\u00e5 grund af brugen af assembleroptimeringer, der manipulerer med 32-bit signed heltal. Et kald til memcpy() p\u00e5 ARMv7-systemer med negativ st\u00f8rrelse f\u00f8rer til forkert sammenligning af v\u00e6rdier og skrivning uden for gr\u00e6nserne af den angivne buffer.<\/p>\n

S\u00e5rbarheden kan udnyttes til at udf\u00f8re kode i en situation, hvor en angriber kan fremkalde et negativt v\u00e6rdig for variablen, der angiver st\u00f8rrelsen af de kopierede data (for eksempel vil en negativ v\u00e6rdi blive skabt ved at overf\u00f8re mere end 2 GB data, men i angrebsprocessen skal der overf\u00f8res mindst 4 GB for at overskride buffergr\u00e6nserne). memcpy()-funktionen anvendes aktivt i applikationer, og ARMv7-processorer er udbredt i bilsystemer, mobile, industrielle, forbruger-, kommunikations- og indlejrede enheder, som potentielt kan blive m\u00e5l for angreb ved brug af Bluetooth, HD Radio\/DAB, USB, CAN bus, Wi-Fi og andre eksterne datakilder (for eksempel kan netv\u00e6rksbaserede tjenester og applikationer, der modtager inputdata uden st\u00f8rrelsesbegr\u00e6nsning, blive angrebet).<\/p>\n

Som eksempel gives oprettelsen af et funktionelt exploit til angreb p\u00e5 den indbyggede http-server i bilens infotainmentsystem, som er tilg\u00e6ngelig via bilens Wi-Fi-netv\u00e6rk. En uautoriseret angriber kan udnytte s\u00e5rbarheden i memcpy i denne server ved at sende en meget stor GET-anmodning og f\u00e5 root-adgang til systemet.<\/p>\n

\"Kritisk<\/a><\/noindex><\/center><\/p>\n

P\u00e5 32-bit x86-systemer optr\u00e6der problemet ikke, da implementeringen af memcpy for denne arkitektur korrekt fortolker st\u00f8rrelsesvariablen som en unsigned heltalv\u00e6rdi af typen size_t (i den assembler-kodede version, implementering<\/a><\/noindex> for ARMv7 behandles den i stedet som signed integer). Fixet er endnu tilg\u00e6ngeligt som et patch<\/a><\/noindex>, som vil blive en del af opdateringen af Glibc 2.32 i august.
\nRetten best\u00e5r i at erstatte brugen af assemblerinstruktioner, der arbejder med tegnoperander (bge og blt), med ubegribelige \u00e6kvivalenter (blo og bhs). <\/p>\n

Problemet er endnu ikke l\u00f8st i Debian 9 og 10<\/a><\/noindex> (det optr\u00e6der ikke i Debian 8), Fedora<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, OpenEmbedded, Tizen (det bruger glibc). RHEL<\/a><\/noindex> og SUSE<\/a><\/noindex> problemet ber\u00f8rer ikke, da de ikke underst\u00f8tter 32-bit ARMv7 systemer. Android er ikke s\u00e5rbar, da det bruger sin egen implementering af libc (Bionic). I OpenWRT<\/a><\/noindex> bruger de fleste builds som standard Musl, men der findes ogs\u00e5 glibc i repository.<\/p>\n

<\/a><\/noindex><\/p>\n

Kilde: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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[…]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":82557,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-82556","post","type-post","status-publish","format-standard","has-post-thumbnail","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\udd47Kritisk s\u00e5rbarhed i implementeringen af memcpy-funktionen til ARMv7 i Glibc | ProHoster","description":"Sikkerhedsforskere fra Cisco afsl\u00f8rede 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