Hi folks,

while playing around I had an idea for some "new kind of mitm" which
works quite well here.

Affected:  All operating systems with unused IPv6 capabilities
    listening to router advertisements (radvd for example)

Attack:    Have an IPv6 tunnel with appropriate prefix delegated.
    Configure your machine to propagate the prefix and
    switch on IPv6 routing.

As soon as the "victim" has an IPv6 address issued by your radvd it will
prefer AAAA-entries over A-entries and connect via your tunnel where
you're waiting with a password sniffer of your choice ;).

This works in any computing center where you have colo'ed you box, have
a dedicated system or...simply physical access. During my
proof-of-concept I was able to intercept SMTP, HTTP and DNS sessions. It
should also work in LANs (lanparties, corporations). The "danger" of
misled connections will dramatically increase with the increasing amount
of ISPs also offering services usable via IPv6. 

Advisory:  Turn off your sever's/client's entire IPv6 capability or
    at least the capability to catch up router
    advertisement messages

I hope you find the contents of my mail useful, entertaining or at least
noch entirely shitty.

Night!