Deflecting Bogus Queries -- Machine Under Attack, PLEASE HELP.

[Dan Mahoney, System Admin]

On Thu, 5 Aug 2004, Sten Carlsen wrote:

> Hi
>
> How about making a local zone for which you are authorative and return "no A 
> record present". At least it will stop any recursive lookups.

I (or the customer, actually) *am* authoritative for elephaunt.org. 
These are not recursive lookups.  But I'm sure this is setting off 
firewall logs at all the spoofed hosts, no matter what I return.

That's why I wanted the "silent ignore" option.  You can do it per IP, but 
not per zone.

-Dan

>
>
> Dan Mahoney wrote:
>
>> I'm presently dealing with a DNS server that's under attack, and is
>> being made to spew out DNS responses all over the internet, hundreds,
>> maybe thousands a second.
>> 
>> I cannot trace the source IP to log it or ban it because it's
>> obviously forged, and there's enough DNS traffic on the wire that it's
>> suitably masked.
>> 
>> I'd like to know if I can just somehow set bind to DROP all queries
>> for the domain in question.  No response, no nothing, just silently
>> ignore them.  It won't make the attack stop, but at least it'll stop
>> me from being used as a reflector.
>> 
>> These domains don't even exist.  I thought about redirecting an NS
>> record for these subdomains elsewhere, but it wouldn't really matter
>> since I think the attack is ignoring true DNS.
>> 
>> Here's a quick log:
>> 
>> Jul 30 19:36:18 cp named[6408]: client 24.158.63.9#53: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 205.152.37.254#42256: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.82.0.5#32770: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 66.215.64.14#54971: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 216.158.48.2#1041: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 24.25.35.64#48487: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 205.188.118.92#33518: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 206.13.30.27#9904: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 167.206.3.232#32772: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 216.68.4.20#3408: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 209.244.4.171#32776: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.46.144.5#34740: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.46.144.5#34740: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.46.144.5#34740: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.46.144.5#34740: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.46.144.5#34740: query:
>> spasm.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 67.32.118.46#32819: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.82.0.5#32770: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.39.224.5#44247: query:
>> spaz.elephaunt.org IN A
>> Jul 30 19:36:18 cp named[6408]: client 68.46.144.5#34740: query:
>> spasm.elephaunt.org IN A
>> 
>> Replies to this address are appreciated, although I will of course
>> check the group.  danm at ezzi dot net is also useful.
>> 
>> 
>
>

--

"We need another cat.  This one's retarded."

-Cali, March 8, 2003 (3:43 AM)

--------Dan Mahoney--------
Techie,  Sysadmin,  WebGeek
Gushi on efnet/undernet IRC
ICQ: 13735144   AIM: LarpGM
Site:  http://www.gushi.org
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