Thursday, 14 August 2008

DNS woes continue... sorta

So as I said, and the original discoverer Dan said, it was just a patch. Not a fix, not a be-all and end all solution. A temporary patch. We already know some nat devices break the patch's fix. But from the looks here and here it can be broken. The first link even details how, but there is a caveat. It is not easy, and a lot of bandwidth with low latency is required.
The first article explains how they did it over Gige in 10 hours. So most DNS servers that are doing resolves for clients, are probably not even on 20mbs of bandwidth, and latency 10+ times that of ethernet, not including the clients themselves causing some load. So you could say it would take 10+ times longer to do this over the internet, so 100hours. Someone will hopefully notice at around hour 20… But it isn't that simple, what if some baddie hits a server with a mere 100 clients... (Most botnets are 10 times this size). Chaos again. We need a better fix. I mentioned before some kind of signed DNS, I am the first to admit I have gaps in my knowledge as I have never heard of DNSSEC, now I that have listened to the Blackhat talk I have heard about it. I had a quick look at wikipedia and the official site and it is interesting. Of course windows servers only support it as a secondary, also the glaring-hole of non NSEC3 servers allowing enumeration of sites is just plain silly. Seriously just hash The users request domain "Not Found" and add it to the RFC, done.
I think it should include the option for encrypting replies, may as well, could be useful for higher secure organisations.
This is a very real and very now threat, there are at least two pieces of software out there to attack it, one being the very good, but very newbie friendly metasploit.
Well I am pretty much just re-iterating and expanding on my comments on darknet but there you go.

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