[Emerging-Sigs] Rule 2016016

Jørgen Bøhnsdalen jurg at jurg.no
Thu Dec 20 07:21:32 HAST 2012


The attack works by sending a small query from a spoofed source IP, which (optimally) results in the server sending a huge response back. See this link:

http://blog.cloudflare.com/deep-inside-a-dns-amplification-ddos-attack

What we've seen though is a bunch of requests to non-dns servers, possibly in an attempt to locate DNS-servers that allow recursive lookup.

- Jørgen

On 12/20/2012 06:19 PM, waldo kitty wrote:
> On 12/20/2012 10:55, Nathan wrote:
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> On 12/20/2012 08:54 AM, Lay, James wrote:
>>> So far this is a pretty chatty rule.  FYI :D
>>
>> It's legit, I had the same thing with 'isc.org' with them asking ANY? isc.org.
>> up and down my CIDR /19.  The guy in this case was 85.195.96.142 and all
>> traffic was sourced from sport 32767 to dport 53.
> 
> i've seen this from only a few times... one was 46.105.36.6 which seems to be game2.kfc-css.com... both the address and the base kfc-css.com are listed in france...
> 
>> I'd give them a firewall block.
> 
> that's what i lie about our active response tool... it initiates a firewall block for alerts and does it pretty danged quickly, too...
> 
> i'm trying to figure out what, exactly, is meant by the rule's MSG text, though... "DNS Amplification"??? what are they trying to do, query DNS via our DNS server(s) and sending a lot of requests for the same addresses?
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-- 
Jørgen Bøhnsdalen
Security Analyst
http://no.linkedin.com/in/jorgenbohnsdalen


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