{"id":115607,"date":"2024-05-07T13:52:17","date_gmt":"2024-05-07T11:52:19","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/ataka-tunnelvision-pozvolyayushhaya-perenapravit-vpn-trafik-cherez-manipulyaczii-s-dhcp"},"modified":"2024-05-07T13:52:17","modified_gmt":"2024-05-07T11:52:19","slug":"ataka-tunnelvision-pozvolyayushhaya-perenapravit-vpn-trafik-cherez-manipulyaczii-s-dhcp","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/ataka-tunnelvision-pozvolyayushhaya-perenapravit-vpn-trafik-cherez-manipulyaczii-s-dhcp","title":{"rendered":"TunnelVision-angrebet, der muligg\u00f8r omdirigering af VPN-trafik gennem manipulation af DHCP","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

TunnelVision er en angrebsmetode, der giver mulighed for at omdirigere offerets trafik til sin egen v\u00e6rt, hvis der er adgang til et lokalt netv\u00e6rk eller kontrol over et tr\u00e5dl\u00f8st netv\u00e6rk, uden at bruge VPN. I stedet for at sende gennem VPN'en vil trafikken blive sendt \u00e5bent uden tunneling til angriberens system. Problemet p\u00e5virker alle VPN-klienter, der ikke bruger isolerede netv\u00e6rksnavneomr\u00e5der (network namespaces) ved rute omdirigering gennem tunnelen eller ikke ops\u00e6tter packet filtering regler, der forbyder routing af VPN-trafik gennem eksisterende fysiske netv\u00e6rksinterfaces. <\/p>\n

Angrebets kerne er, at angriberen kan starte sin egen DHCP-server og bruge den til at overf\u00f8re information til klienten for at \u00e6ndre routing. Specifikt kan angriberen udnytte den DHCP-option 121 (RFC-3442, vedtaget i 2002), der er beregnet til at videregive oplysninger om statiske ruter, til at \u00e6ndre routing-tabellen p\u00e5 offerets maskine og dirigere trafikken udenom. VPN<\/a>. Omdirigeringen sker ved at indstille en r\u00e6kke ruter for undernet med pr\u00e6fikset \/1, som har en h\u00f8jere prioritet end den standardrute med pr\u00e6fikset \/0 (0.0.0.0\/0), hvilket betyder, at trafikken i stedet for at g\u00e5 gennem den tildelte VPN virtuelle netv\u00e6rksinterface vil blive sendt gennem det fysiske netv\u00e6rksinterface til angriberens v\u00e6rt i det lokale netv\u00e6rk. <\/p>\n

Angrebet kan udf\u00f8res p\u00e5 alle operativsystemer, der underst\u00f8tter DHCP-option 121, herunder Linux, Windows, iOS og macOS, uafh\u00e6ngigt af den anvendte VPN-protokol (Wireguard, OpenVPN, IPsec) og combos af kryptering. Android-platformen er ikke s\u00e5rbar, da den ikke behandler option 121 i DHCP. Angrebet giver dog adgang til trafikken, men muligg\u00f8r ikke indtr\u00e6ngen i forbindelserne eller bestemmelse af indholdet, der sendes ved hj\u00e6lp af sikre applikationsprotokoller som TLS og SSH. For eksempel kan angriberen ikke fastsl\u00e5 indholdet af HTTPS-anmodninger, men kan forst\u00e5, hvilke servere de sendes til. <\/p>\n

For protection against attacks, it is possible to prohibit the sending of packets addressed to the VPN interface through other network interfaces at the packet filter level; block DHCP packets with option 121; use the VPN within a separate virtual machine (or container) isolated from the external network, or apply special tunnel configuration modes using namespaces in Linux (network namespace). A set of scripts has been published for experiments with conducting the attack.

\r\n \"Afspil\r\n
<\/div>\r\n <\/div> <\/center> <\/p>\n

It should be noted that the idea of local routing changes is not new and has previously been used in attacks aimed at DNS server substitution. In a similar attack, TunnelCrack, where traffic redirection was achieved by replacing the default gateway, the problem affected all tested VPN clients for iOS, 87.5% of VPN clients for macOS, 66.7% for Windows, 35.7% for Linux, and 21.4% for Android. In the context of VPN and DHCP, this method was also mentioned earlier, for example, one of the reports at last year's USENIX 2023 conference discussed it (the study showed that 64.6% of the 195 tested VPN clients were vulnerable to the attack). <\/p>\n

For routing substitutions, it was also suggested to use a specially designed USB flash drive that simulates the operation of a network adapter, which declares itself as a gateway when connected to a computer via DHCP. Additionally, when the gateway is controlled (for example, when the victim connects to a wireless network controlled by the attacker), a technique for injecting packets into the tunnel, perceived in the context of the VPN network interface, was developed. <\/p>\n

Data flows while using VPN:

\"TunnelVision-angrebet,<\/center> <\/p>\n

Data flows after the attack has been executed:

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

\u0412\u043d\u0438\u043c\u0430\u043d\u0438\u044e \u043f\u0443\u0431\u043b\u0438\u043a\u0438 \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d \u043c\u0435\u0442\u043e\u0434 \u0430\u0442\u0430\u043a\u0438 TunnelVision, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0439 \u043f\u0440\u0438 \u043d\u0430\u043b\u0438\u0447\u0438\u0438 \u0434\u043e\u0441\u0442\u0443\u043f\u0430 \u043a \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u0439 \u0441\u0435\u0442\u0438 \u0438\u043b\u0438 \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u044f \u043d\u0430\u0434 \u0431\u0435\u0441\u043f\u0440\u043e\u0432\u043e\u0434\u043d\u043e\u0439 \u0441\u0435\u0442\u044c\u044e, \u043e\u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0438\u0442\u044c \u043f\u0435\u0440\u0435\u043d\u0430\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u0435 \u043d\u0430 \u0441\u0432\u043e\u0439 \u0445\u043e\u0441\u0442 \u0442\u0440\u0430\u0444\u0438\u043a\u0430 \u0436\u0435\u0440\u0442\u0432\u044b \u0432 \u043e\u0431\u0445\u043e\u0434 VPN (\u0432\u043c\u0435\u0441\u0442\u043e \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0438 \u0447\u0435\u0440\u0435\u0437 VPN, \u0442\u0440\u0430\u0444\u0438\u043a \u0431\u0443\u0434\u0435\u0442 \u043e\u0442\u043f\u0440\u0430\u0432\u043b\u0435\u043d \u0432 \u043e\u0442\u043a\u0440\u044b\u0442\u043e\u043c \u0432\u0438\u0434\u0435 \u0431\u0435\u0437 \u0442\u0443\u043d\u043d\u0435\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u043d\u0430 \u0441\u0438\u0441\u0442\u0435\u043c\u0443 \u0430\u0442\u0430\u043a\u0443\u044e\u0449\u0435\u0433\u043e). \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0435 \u043f\u043e\u0434\u0432\u0435\u0440\u0436\u0435\u043d\u044b \u043b\u044e\u0431\u044b\u0435 VPN-\u043a\u043b\u0438\u0435\u043d\u0442\u044b, \u043d\u0435 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044e\u0449\u0438\u0435 \u0438\u0437\u043e\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u0435 \u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u0441\u0442\u0432\u0430 \u0438\u043c\u0451\u043d \u0441\u0435\u0442\u0435\u0432\u043e\u0439 \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u044b (network […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":115608,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-115607","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\udd47The TunnelVision attack allows for redirecting VPN traffic through DHCP manipulations | ProHoster","description":"The method of attack TunnelVision has been presented to the public, allowing 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