{"id":76196,"date":"2020-03-31T19:42:05","date_gmt":"2020-03-31T17:42:05","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf"},"modified":"2020-03-31T19:42:05","modified_gmt":"2020-03-31T17:42:05","slug":"uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/news\/uyazvimost-v-yadre-linux-pozvolyayushhaya-povysit-svoi-privilegii-cherez-bpf","title":{"rendered":"Zranite\u013enos\u0165 v jadre Linuxu, ktor\u00e1 umo\u017e\u0148uje zv\u00fd\u0161i\u0165 svoje privil\u00e9gi\u00e1 cez BPF","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Boli zverejnen\u00e9<\/a><\/noindex> inform\u00e1cie o zranite\u013enosti (CVE-2020-8835<\/a><\/noindex>) v jadre Linux, ktor\u00e1 bola vyu\u017eit\u00e1 na s\u00fa\u0165a\u017ei Pwn2Own 2020<\/a><\/noindex> pri demon\u0161tr\u00e1cii hackovania Ubuntu. Zranite\u013enos\u0165 umo\u017enila neprivilegovan\u00e9mu pou\u017e\u00edvate\u013eovi z\u00edska\u0165 pr\u00e1va root. Funguj\u00faci exploit existuje, ale zatia\u013e nebol zverejnen\u00fd. Zranite\u013enos\u0165 sa nach\u00e1dza v subsyst\u00e9me eBPF, ktor\u00fd umo\u017e\u0148uje sp\u00fa\u0161\u0165a\u0165 spracovate\u013eov na trasovanie, anal\u00fdzu \u010dinnosti subsyst\u00e9mov a spr\u00e1vu prev\u00e1dzky vykon\u00e1van\u00fa v jadre v \u0161peci\u00e1lnej virtu\u00e1lnej ma\u0161ine s JIT.<\/p>\n

Probl\u00e9m je sp\u00f4soben\u00fd chybou vo funkcii __reg_bound_offset32(), ktor\u00e1 sa pou\u017e\u00edva na kontrolu 32-bitov\u00fdch oper\u00e1ci\u00ed v bajtk\u00f3de BPF. V d\u00f4sledku nespr\u00e1vneho v\u00fdpo\u010dtu hran\u00edc registru, pri spracovan\u00ed \u0161peci\u00e1lne zostaven\u00fdch BPF aplik\u00e1ci\u00ed vznikali podmienky na zapisovanie a \u010d\u00edtanie \u00fadajov mimo pridelen\u00e9ho bufferu v oblasti pam\u00e4te jadra. Probl\u00e9m sa objavil v jadre 5.5 a nesk\u00f4r pri sp\u00e4tnej integr\u00e1cii opr\u00e1v bol prenesen\u00fd do jadra 5.4, ako aj do bal\u00edka s jadrom 5.3<\/a><\/noindex>, pon\u00fakan\u00e9ho v Ubuntu Linux.<\/p>\n

Na zablokovanie zranite\u013enosti sa odpor\u00fa\u010da vr\u00e1ti\u0165<\/a><\/noindex> probl\u00e9mov\u00fd patch alebo zak\u00e1za\u0165 vykon\u00e1vanie BPF aplik\u00e1ci\u00ed neprivilegovan\u00fdmi pou\u017e\u00edvate\u013emi nastaven\u00edm sysctl kernel.unprivileged_bpf_disabled na hodnotu 1. Stav opravy v distrib\u00faci\u00e1ch: Ubuntu<\/a><\/noindex>, Debian<\/a><\/noindex>, Arch<\/a><\/noindex>, Fedora<\/a><\/noindex> a SUSE<\/a><\/noindex> (v jadr\u00e1ch RHEL<\/a><\/noindex> probl\u00e9mov\u00e1 zmena sa nepren\u00e1\u0161ala).<\/p>\n

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

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

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