{"id":102308,"date":"2021-11-17T21:36:54","date_gmt":"2021-11-17T19:36:54","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/novyj-variant-ataki-sad-dns-dlya-podstanovki-fiktivnyh-dannyh-v-kesh-dns"},"modified":"2021-11-17T21:36:54","modified_gmt":"2021-11-17T19:36:54","slug":"novyj-variant-ataki-sad-dns-dlya-podstanovki-fiktivnyh-dannyh-v-kesh-dns","status":"publish","type":"post","link":"https:\/\/prohoster.info\/et\/blog\/novosti-interneta\/novyj-variant-ataki-sad-dns-dlya-podstanovki-fiktivnyh-dannyh-v-kesh-dns","title":{"rendered":"Uus SAD DNS r\u00fcnnaku variant valeandmete sisestamiseks DNS vahem\u00e4llu","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Kalifornias Riverside'i \u00fclikooli teadlaste r\u00fchm on avaldanud uue SAD DNS r\u00fcnnaku variandi (CVE-2021-20322), mis t\u00f6\u00f6tab vaatamata eelmisel aastal lisatud kaitsele CVE-2020-25705 haavatavuse blokeerimiseks. Uus meetod sarnaneb suures osas eelmisel aastal avastatud haavatavusele ja erineb ainult aktiivsete UDP-portide kontrollimiseks kasutatavate ICMP-pakettide t\u00fc\u00fcbiga. Ettepanek r\u00fcnnak v\u00f5imaldab valeandmete sisestamist DNS serveri vahem\u00e4llu, mida saab kasutada, et asendada suvalise domeeni IP-aadress vahem\u00e4lus ja suunata domeeni p\u00e4ringud kurjategija serverisse. <\/p>\n

Ettepanekud meetod t\u00f6\u00f6tab ainult Linuxi v\u00f5rgu stack'is, kuna see s\u00f5ltub Linuxi ICMP-pakettide t\u00f6\u00f6tlemise mehhanismi omadustest, mis on andmelekke allikaks ja lihtsustavad UDP-porti numbri m\u00e4\u00e4ramist. serveriga<\/a> v\u00e4liste p\u00e4ringute saatmiseks. Muudatused, mis takistavad teabe leket, on lisatud Linuxi tuuma augusti l\u00f5pus (parandus on kaasatud versioonis 5.15 ja septembri LTS-kate v\u00e4rskendustes). Parandus seisneb \u00fcleminekus v\u00f5rgu vahem\u00e4lu kasutamisel SipHashi hashimise algoritmile Jenkins Hashi asemel. Haavatavuse k\u00f5rvaldamise staatust jaotustes saab hinnata j\u00e4rgmistelt lehtedelt: Debian, RHEL, Fedora, SUSE, Ubuntu. <\/p>\n

Probleemi avastanud teadlaste andmetel on umbes 38% Internetis olevatest avatud resolveerijatest haavatavad, sealhulgas populaarsed DNS-teenused nagu OpenDNS ja Quad9 (9.9.9.9). Mis puudutab serveri tarkvara, siis saab r\u00fcnnaku teostada Linuxi serveris, kasutades selliseid pakette nagu BIND, Unbound ja dnsmasq. Windowsi ja BSD-s\u00fcsteemide peal t\u00f6\u00f6tavatel DNS-serveritel probleem ei avaldu. R\u00fcnnaku edukaks teostamiseks on vajalik IP-spoofing, st r\u00fcndaja teenusepakkuja ei tohi blokeerida vale algse IP-aadressiga pakette. <\/p>\n

Tuletame meelde, et SAD DNS r\u00fcnnak v\u00f5imaldab m\u00f6\u00f6da minna kaitsetest, mis on lisatud DNS-serveritesse, et blokeerida klassikalisi DNS-i vahem\u00e4lu m\u00fcrgitamise meetodeid, mille pakkus v\u00e4lja 2008. aastal Dan Kaminsky. Kaminsky meetod manipuleerib DNS-i p\u00e4ringu identifikaatori v\u00e4lja v\u00e4hese suurusega, mis on vaid 16 bitti. \u00d5ige DNS-tehingu identifikaatori, mis on vajalik hostinime vale esitlemiseks, leidmiseks piisab umbes 7000 p\u00e4ringu saatmisest ja umbes 140 000 vale vastuse simuleerimisest. R\u00fcnnak seisneb DNS-i lahendajale suurte koguste valeadressiga pakettide saatmises, millel on erinevad DNS-i tehingu identifikaatorid. Iga vale vastuse puhul, et v\u00e4ltida esimese vastuse vahem\u00e4llu salvestamist, m\u00e4\u00e4ratakse veidi muudetud domeeninimi (1.example.com, 2.example.com, 3.example.com jne). <\/p>\n

Selle r\u00fcnnaku kaitsmiseks on DNS-serverite tootjad rakendanud juhuslikku l\u00e4hteportide nummerdamist, millest saatakse resolutsioonik\u00fcsimused, mis kompenseerib identifikaatori piisavalt suurt suurust. P\u00e4rast kaitse rakendamist on valevastuse saatmiseks lisaks 16-bitise identifikaatori valimisele vajalik ka valida \u00fcks 64 000 sadamast, mis suurendas valikute arvu 2^32. <\/p>\n

SAD DNS meetod muudab v\u00f5rguportide numbrite tuvastamise \u00e4\u00e4rmiselt lihtsaks ja viib r\u00fcnnaku tagasi klassikalisse Kaminski meetodisse. R\u00fcndaja v\u00f5ib tuvastada taotlusi kasutamata ja aktiivsetele UDP-pordile, kasutades v\u00f5rguportide tegevuse kohta teabe lekkimist, mis toimub ICMP-pakettide vastuste t\u00f6\u00f6tlemisel. Meetod v\u00e4hendab valikute arvu 4 korda \u2014 2^16+2^16 asemel 2^32 (131_072 asemel 4_294_967_296). Teave, mis v\u00f5imaldab kiiresti kindlaks teha aktiivsed UDP-pordid, lekib koodivea t\u00f5ttu ICMP-pakettide t\u00f6\u00f6tlemises fraktsioneerimise p\u00e4ringute (ICMP Fragmentation Needed lipp) v\u00f5i \u00fcmbersuunamiste (ICMP Redirect lipp) puhul. Selliste paketide saatmine muudab v\u00f5rgu virna vahem\u00e4lu staatust, v\u00f5imaldades serveri reaktsiooni p\u00f5hjal kindlaks teha, milline UDP-port on aktiivne ja milline mitte. <\/p>\n

R\u00fcnnakustsenaarium: Kui DNS-resolver \u00fcritab kindlaks teha domeeninime, saadab ta UDP-p\u00e4ringu DNS-serverile, mis haldab domeeni. Sel hetkel, kui resolver ootab vastust, suudab r\u00fcndaja kiiresti tuvastada algse pordi numbri, mida kasutatakse p\u00e4ringu saatmiseks, ja saata sellele valevastuse, esinedes DNS-serverina, kasutades valeidentiteeti. IP-aadressid<\/a>DNS-resolver salvestab valevastustes edastatud andmed vahem\u00e4llu ning teatud aja jooksul tagastab ta k\u00f5ikidele teistele domeeninime DNS-p\u00e4ringutele r\u00fcndaja esitatud IP-aadressi.
\n
Allikas: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0413\u0440\u0443\u043f\u043f\u0430 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439 \u0438\u0437 \u041a\u0430\u043b\u0438\u0444\u043e\u0440\u043d\u0438\u0439\u0441\u043a\u043e\u0433\u043e \u0443\u043d\u0438\u0432\u0435\u0440\u0441\u0438\u0442\u0435\u0442\u0430 \u0432 \u0420\u0438\u0432\u0435\u0440\u0441\u0430\u0439\u0434\u0435 \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b\u0430 \u043d\u043e\u0432\u044b\u0439 \u0432\u0430\u0440\u0438\u0430\u043d\u0442 \u0430\u0442\u0430\u043a\u0438 SAD DNS (CVE-2021-20322), \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u043d\u0435\u0441\u043c\u043e\u0442\u0440\u044f \u043d\u0430 \u0437\u0430\u0449\u0438\u0442\u0443, \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u043d\u0443\u044e \u0432 \u043f\u0440\u043e\u0448\u043b\u043e\u043c \u0433\u043e\u0434\u0443 \u0434\u043b\u044f \u0431\u043b\u043e\u043a\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 CVE-2020-25705. \u041d\u043e\u0432\u044b\u0439 \u043c\u0435\u0442\u043e\u0434 \u0432 \u0446\u0435\u043b\u043e\u043c \u0430\u043d\u0430\u043b\u043e\u0433\u0438\u0447\u0435\u043d \u043f\u0440\u043e\u0448\u043b\u043e\u0433\u043e\u0434\u043d\u0435\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0438 \u043e\u0442\u043b\u0438\u0447\u0430\u0435\u0442\u0441\u044f \u043b\u0438\u0448\u044c \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c \u0434\u0440\u0443\u0433\u043e\u0433\u043e \u0442\u0438\u043f\u0430 ICMP-\u043f\u0430\u043a\u0435\u0442\u043e\u0432 \u0434\u043b\u044f \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u0430\u043a\u0442\u0438\u0432\u043d\u044b\u0445 UDP-\u043f\u043e\u0440\u0442\u043e\u0432. \u041f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u043d\u0430\u044f \u0430\u0442\u0430\u043a\u0430 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u043e\u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0438\u0442\u044c \u043f\u043e\u0434\u0441\u0442\u0430\u043d\u043e\u0432\u043a\u0443 \u0444\u0438\u043a\u0442\u0438\u0432\u043d\u044b\u0445 \u0434\u0430\u043d\u043d\u044b\u0445 \u0432 \u043a\u044d\u0448 DNS-\u0441\u0435\u0440\u0432\u0435\u0440\u0430, \u0447\u0442\u043e […]<\/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-102308","post","type-post","status-publish","format-standard","hentry","category-novosti-interneta"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\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\n","aioseo_head_json":{"title":"\ud83e\udd47Uus SAD DNS r\u00fcnnakute variant valeandmete sisestamiseks DNS vahem\u00e4lu | ProHoster","description":"Kalifornia \u00dclikooli Riverside'i teadlaste grupp on avaldanud uue SAD DNS r\u00fcnnaku variandi (CVE-2021-20322), mis t\u00f6\u00f6tab vaatamata eelmisel aastal lisatud kaitsele, mis piiras CVE-2020-25705 haavatavust. Uus meetod on \u00fcldiselt sarnane m\u00f6\u00f6dunud aasta haavatavusele ja eristub vaid erineva t\u00fc\u00fcpi ICMP-pakettide kasutamisega, et kontrollida aktiivseid UDP-Ports. Ettepanekuline r\u00fcnnak v\u00f5imaldab sisestada valeandmeid DNS-serveri vahem\u00e4llu.","canonical_url":"https:\/\/prohoster.info\/et\/blog\/novosti-interneta\/novyj-variant-ataki-sad-dns-dlya-podstanovki-fiktivnyh-dannyh-v-kesh-dns","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"et_EE","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\u041d\u043e\u0432\u044b\u0439 \u0432\u0430\u0440\u0438\u0430\u043d\u0442 \u0430\u0442\u0430\u043a\u0438 SAD DNS \u0434\u043b\u044f \u043f\u043e\u0434\u0441\u0442\u0430\u043d\u043e\u0432\u043a\u0438 \u0444\u0438\u043a\u0442\u0438\u0432\u043d\u044b\u0445 \u0434\u0430\u043d\u043d\u044b\u0445 \u0432 \u043a\u044d\u0448 DNS | ProHoster","og:description":"\u0413\u0440\u0443\u043f\u043f\u0430 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0435\u0439 \u0438\u0437 \u041a\u0430\u043b\u0438\u0444\u043e\u0440\u043d\u0438\u0439\u0441\u043a\u043e\u0433\u043e \u0443\u043d\u0438\u0432\u0435\u0440\u0441\u0438\u0442\u0435\u0442\u0430 \u0432 \u0420\u0438\u0432\u0435\u0440\u0441\u0430\u0439\u0434\u0435 \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b\u0430 \u043d\u043e\u0432\u044b\u0439 \u0432\u0430\u0440\u0438\u0430\u043d\u0442 \u0430\u0442\u0430\u043a\u0438 SAD DNS (CVE-2021-20322), \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u043d\u0435\u0441\u043c\u043e\u0442\u0440\u044f \u043d\u0430 \u0437\u0430\u0449\u0438\u0442\u0443, \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u043d\u0443\u044e \u0432 \u043f\u0440\u043e\u0448\u043b\u043e\u043c \u0433\u043e\u0434\u0443 \u0434\u043b\u044f \u0431\u043b\u043e\u043a\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 CVE-2020-25705. \u041d\u043e\u0432\u044b\u0439 \u043c\u0435\u0442\u043e\u0434 \u0432 \u0446\u0435\u043b\u043e\u043c \u0430\u043d\u0430\u043b\u043e\u0433\u0438\u0447\u0435\u043d \u043f\u0440\u043e\u0448\u043b\u043e\u0433\u043e\u0434\u043d\u0435\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0438 \u043e\u0442\u043b\u0438\u0447\u0430\u0435\u0442\u0441\u044f \u043b\u0438\u0448\u044c \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c \u0434\u0440\u0443\u0433\u043e\u0433\u043e \u0442\u0438\u043f\u0430 ICMP-\u043f\u0430\u043a\u0435\u0442\u043e\u0432 \u0434\u043b\u044f \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0438 \u0430\u043a\u0442\u0438\u0432\u043d\u044b\u0445 UDP-\u043f\u043e\u0440\u0442\u043e\u0432. \u041f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u043d\u0430\u044f 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