Re: "BIND 9 DNS Cache Poisoning" by Amit Klein (Trusteer)

On Thu, Jul 26, 2007 at 11:40:55PM -0500, Gadi Evron wrote:
> This is Paul Vixie's response on this, when I asked him for verification:
>
> -----
> this bug has been reported over and over again for a dozen years. it's
> odd to have to keep fixing it-- i fixed it in bind4 and bind8 when theo
> de raadt offered me his random number generator to use. bind9 should've
> used that same one but apparently didn't. note that with this fix, the
> difficulty in poisoning someone's cache rises from "a few tens of seconds"
> to "a few minutes". it's a 16-bit field. not a lot of room for
> randomness or unpredictability. only DNSSEC, a protocol change, fixes
> this problem, which is fundamentally a protocol problem. but since folks
> just won't leave it alone and keep on reporting it year after decade, we
> will keep on improving our random number generator for this dinky little
> 16-bit field. i just wish the reporters wouldn't be so smarmy and self
> congradulatory about it. it's not like this hasn't been reported, and
> fixed, many times by many others.
> -----

Note that this conveniently ignores the option to use randomized port numbers... No, it is a pretty fix, but it sure does help.

tim Received on Fri Jul 27 12:48:04 2007