{"id":73151,"date":"2020-03-07T14:42:03","date_gmt":"2020-03-07T11:42:03","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-pppd-i-lwip-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root"},"modified":"2020-03-07T14:42:03","modified_gmt":"2020-03-07T11:42:03","slug":"uyazvimost-v-pppd-i-lwip-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-pppd-i-lwip-pozvolyayushhaya-udalyonno-vypolnit-kod-s-pravami-root","title":{"rendered":"Zranitelnost v pppd a lwIP, kter\u00e1 umo\u017e\u0148uje vzd\u00e1len\u00e9 vykon\u00e1n\u00ed k\u00f3du s pr\u00e1vy roota","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V bal\u00ed\u010dku pppd byla odhalena<\/a><\/noindex> zranitelnost<\/a><\/noindex> (CVE-2020-8597<\/a><\/noindex>), kter\u00e1 umo\u017e\u0148uje spou\u0161t\u011bn\u00ed vlastn\u00edho k\u00f3du prost\u0159ednictv\u00edm odes\u00edl\u00e1n\u00ed speci\u00e1ln\u011b upraven\u00fdch autentiza\u010dn\u00edch po\u017eadavk\u016f do syst\u00e9m\u016f vyu\u017e\u00edvaj\u00edc\u00edch protokol PPP (Point-to-Point Protocol) nebo PPPoE (PPP over Ethernet). Tyto protokoly jsou b\u011b\u017en\u011b vyu\u017e\u00edv\u00e1ny poskytovateli k zaji\u0161t\u011bn\u00ed p\u0159ipojen\u00ed p\u0159es Ethernet nebo DSL, a tak\u00e9 se pou\u017e\u00edvaj\u00ed v n\u011bkter\u00fdch VPN (nap\u0159\u00edklad pptpd a openfortivpn<\/a><\/noindex>). Pro ov\u011b\u0159en\u00ed zranitelnosti sv\u00fdch syst\u00e9m\u016f p\u0159ipraven<\/a><\/noindex> prototyp exploit.<\/p>\n

Zranitelnost je zp\u016fsobena p\u0159ete\u010den\u00edm bufferu v implementaci autentiza\u010dn\u00edho protokolu EAP (Extensible Authentication Protocol). \u00datok m\u016f\u017ee b\u00fdt proveden ji\u017e ve f\u00e1zi p\u0159ed autentizac\u00ed odesl\u00e1n\u00edm paketu s typem EAPT_MD5CHAP, kter\u00fd obsahuje velmi dlouh\u00e9 jm\u00e9no hostitele, kter\u00e9 se nevejde do vyhrazen\u00e9ho bufferu. V d\u016fsledku chyby v kontrole velikosti pole rhostname m\u016f\u017ee \u00fato\u010dn\u00edk p\u0159epsat data za hranice bufferu na z\u00e1sobn\u00edku a dos\u00e1hnout vzd\u00e1len\u00e9ho spu\u0161t\u011bn\u00ed sv\u00e9ho k\u00f3du s pr\u00e1vy root. Zranitelnost se projevuje na stran\u011b serveru a klienta, tj. m\u016f\u017ee b\u00fdt napad\u00e1n nejen server, ale i klient, kter\u00fd se pokou\u0161\u00ed p\u0159ipojit k serveru kontrolovan\u00e9mu \u00fato\u010dn\u00edkem (nap\u0159\u00edklad \u00fato\u010dn\u00edk m\u016f\u017ee nejprve kompromitovat server prost\u0159ednictv\u00edm zranitelnosti a pot\u00e9 za\u010d\u00edt napadat p\u0159ipojuj\u00edc\u00ed se klienty).<\/p>\n

Probl\u00e9m se t\u00fdk\u00e1 verz\u00ed pppd<\/a><\/noindex> od 2.4.2 do 2.4.8 v\u010detn\u011b a byl odstran\u011bn ve form\u011b patche<\/a><\/noindex>. Zranitelnost se tak\u00e9 ovliv\u0148uje<\/a><\/noindex> z\u00e1sobn\u00edk lwIP<\/a><\/noindex>, ale v v\u00fdchoz\u00ed konfiguraci v lwIP nen\u00ed podpora EAP povolena.<\/p>\n

Stav odstran\u011bn\u00ed probl\u00e9mu v distribuc\u00edch lze zjistit na n\u00e1sleduj\u00edc\u00edch str\u00e1nk\u00e1ch: Debian<\/a><\/noindex>, Ubuntu<\/a><\/noindex>, RHEL<\/a><\/noindex>, Fedora<\/a><\/noindex>, SUSE<\/a><\/noindex>, OpenWRT<\/a><\/noindex>, Arch<\/a><\/noindex>, NetBSD<\/a><\/noindex>. V RHEL, OpenWRT a SUSE je bal\u00ed\u010dek pppd slo\u017een s aktivovanou ochranou \u201eStack Smashing Protection\u201c (re\u017eim \u201e-fstack-protector\u201c v gcc), co\u017e omezuje zneu\u017eit\u00ed zp\u016fsoben\u00e9 p\u00e1dem. Krom\u011b distribuc\u00ed byla zranitelnost tak\u00e9 potvrzena v n\u011bkter\u00fdch produktech. Cisco<\/a><\/noindex> (CallManager), TP-LINK<\/a><\/noindex> a Synology (DiskStation Manager, VisualStation VS960HD a Router Manager), kter\u00e9 pou\u017e\u00edvaj\u00ed k\u00f3d pppd nebo lwIP.<\/p>\n

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

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

\u0412 \u043f\u0430\u043a\u0435\u0442\u0435 pppd \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2020-8597), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u0441\u0432\u043e\u0439 \u043a\u043e\u0434 \u0447\u0435\u0440\u0435\u0437 \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0443 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0445 \u0437\u0430\u043f\u0440\u043e\u0441\u043e\u0432 \u043d\u0430 \u0430\u0443\u0442\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u044e \u043a \u0441\u0438\u0441\u0442\u0435\u043c\u0430\u043c, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044e\u0449\u0438\u043c \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b PPP (Point-to-Point Protocol) \u0438\u043b\u0438 PPPoE (PPP over Ethernet). \u0414\u0430\u043d\u043d\u044b\u0435 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u044b \u043e\u0431\u044b\u0447\u043d\u043e \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u044e\u0442\u0441\u044f \u043f\u0440\u043e\u0432\u0430\u0439\u0434\u0435\u0440\u0430\u043c\u0438 \u0434\u043b\u044f \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u043f\u043e\u0434\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u044f \u0447\u0435\u0440\u0435\u0437 Ethernet \u0438\u043b\u0438 DSL, \u0430 \u0442\u0430\u043a\u0436\u0435 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044e\u0442\u0441\u044f \u0432 \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0445 VPN (\u043d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, pptpd \u0438 openfortivpn). \u0414\u043b\u044f \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u043f\u043e\u0434\u0432\u0435\u0440\u0436\u0435\u043d\u043d\u043e\u0441\u0442\u0438 \u0441\u0432\u043e\u0438\u0445 […]<\/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-73151","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\udd47 Zranitelnost v pppd a lwIP, kter\u00e1 umo\u017e\u0148uje vzd\u00e1len\u00e9 spu\u0161t\u011bn\u00ed k\u00f3du s pr\u00e1vy root | ProHoster","description":"V bal\u00ed\u010dku pppd byla zji\u0161t\u011bna 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