Re: Request assistance regarding VRT sig 1:27962 (MALWARE-CNC Win.Trojan.Storm botnet connection reset)

[James Lay <jlay () slave-tothe-box net>]

And FYI this is commented out in my rulesets…which I've not monkeyed with at all (either by hand or with PP).  I'd take 
a peek at your pulled pork *sid.conf files.

James

On Oct 4, 2013, at 8:27 PM, nicenate () verizon net wrote:

> On 10/04/13, James Lay wrote:
>
> On Oct 4, 2013, at 6:21 PM, "Mathewson, Nathan" <Mathewson () kennedykrieger org> wrote:
>
> We have most of the Malware-CNC rules enabled and we installed the VRT rule update from 9-24-2013. We are now seeing 
> alerts form this sig 1:27962. We see user machines sending from one to three TCP SYN packets out and receiving back 
> RST/ACK packets with a reset cause ?Go away, we?re not home?, exactly as the rule requires. 
>
> This appears to be a ?new? snort vrt rule in this rule set yet it only references sources from 2008.
>
> We have not been able to find explanations for why one receives these unique RST/ACK packets. 
>
> Can anyone assist us with information regarding this sig, why this rule was seemingly just added, it?s current 
> status, and what might be the cause[s] for these resets with this unique ?reset cause?.
>
> Attached file is a sample SYN ? RST/ACK, in pcap format.
>
> Appreciate your assistance.
>
> Nathan
>
> Take your pick on one of these:
>
> https://duckduckgo.com/?q=RST+ACK+%22Go+away+we%27re+not+home%22
>
> Interesting reading.
>
> James
>
>
> Thanks James.
>
> Am a big fan of duckduckgo and we also googled, a lot.  Seen all of these... as this was one of our first searches.
>
> So far, I think the most  likely cause seems to be that some machines -for some unknown reason- are trying to make 
> connections to IPs running a cable-modem router-nat-box which when replies with this response in the Rset ACK packet. 
>  Of course there are two obvious questions, one bing why is one of our machines trying to make the TCP connection at 
> all; and secondly, what device is set to send tcp reset-acks with this phrase as the reset cause. 
>
> Anyone know of devices set to issue resets in this manner, i.e. with this reset cause phrase?  
>
> Anyone have an idea why the Snort VRT group decided to add this seemingly 'old rule' as a new rule in the 24 Sept 
> rule set release?  Was the VRT group aware of some 'new threat' out there acting like the old Storm C-and-C machines?
>
> Thanks,  Nathan

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