What DNS Is Not

Andrew Cox andrew at accessplus.com.au
Tue Nov 10 04:15:19 UTC 2009

Shouldn't such apps be checking the content they receive back from a 
server anyway?
Regardless of if they think they're getting to the right server (due to 
a bogus non-NXDOMAIN response) there should be some sort of validation 
in place.. otherwise you're open in any sort of man-in-the-middle attack.

I think the issue is more that older apps would expect that if they can 
get a response then everything is ok.. perhaps this simply an outdated 
method and needs to be rethought.

Valdis.Kletnieks at vt.edu wrote:
> On Mon, 09 Nov 2009 15:04:06 PST, Bill Stewart said:
>> For instance, returning the IP address of your company's port-80 web
>> server instead of NXDOMAIN
>> not only breaks non-port-80-http applications
> Remember this...
>> There is one special case for which I don't mind having DNS servers
>> lie about query results,
>> which is the phishing/malware protection service.  In that case, the
>> DNS response is redirecting you to
>> the IP address of a server that'll tell you
>>        "You really didn't want to visit PayPa11.com - it's a fake" or
>>        "You really didn't want to visit
>> dgfdsgsdfgdfgsdfgsfd.example.ru - it's malware".
>> It's technically broken, but you really _didn't_ want to go there anyway.
>> It's a bit friendlier to administrators and security people if the
>> response page gives you the
> Returning bogus non-NXODMAIN gives non-port-80-http apps heartburn as well.

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