[secdir] Routing loop attacks using IPv6 tunnels

Gabi Nakibly <gnakibly@yahoo.com> Mon, 17 August 2009 15:22 UTC

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Date: Mon, 17 Aug 2009 08:21:12 -0700 (PDT)
From: Gabi Nakibly <gnakibly@yahoo.com>
To: v6ops <v6ops@ops.ietf.org>
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Cc: ipv6@ietf.org, secdir@ietf.org
Subject: [secdir] Routing loop attacks using IPv6 tunnels
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Hi all,
I would like to draw the attention of the list to some research results which my colleague and I at the National EW Research & Simulation Center have recently published. The research presents a class of routing loop attacks that abuses 6to4, ISATAP and Teredo. The paper can be found at: http://www.usenix.org/events/woot09/tech/full_papers/nakibly.pdf

Here is the abstract:
IPv6 is the future network layer protocol for the Internet. Since it is not compatible with its predecessor, some interoperability mechanisms were designed. An important category of these mechanisms is automatic tunnels, which enable IPv6 communication over an IPv4 network without prior configuration. This category includes ISATAP, 6to4 and Teredo. We present a novel class of attacks that exploit vulnerabilities in these tunnels. These attacks take advantage of inconsistencies between a tunnel's overlay IPv6 routing state and the native IPv6 routing state. The attacks form routing loops which can be abused as a vehicle for traffic amplification to facilitate DoS attacks. We exhibit five attacks of this class. One of the presented attacks can DoS a Teredo server using a single packet. The exploited vulnerabilities are embedded in the design of the tunnels; hence any implementation of these tunnels may be vulnerable. In particular, the attacks were tested
 against the ISATAP, 6to4 and Teredo implementations of Windows Vista and Windows Server 2008 R2. 

I think the results of the research warrant some corrective action. If this indeed shall be the general sentiment of the list, I will be happy write an appropriate I-D. The mitigation measures we suggested in the paper are the best we could think of to completely eliminate the problem. However they are far from perfect since they would require tunnel implementations to be updated in case new types of automatic tunnels are introduced.

Your comments are welcome.

Gabi