Re: Feasibility of one off rule

[Alex Kirk <akirk () sourcefire com>]

In principle, probably not a bad idea. In practice, there's a bit of an
implementation challenge.

The issue is performance. You'd need something to stick in the fast pattern
matcher - thus, a fixed string that shouldn't be too common - to make it
more than "if I see traffic on these ports, fire", and thus make it not
slow. I suppose you would't see "GET" very often on off ports, so that might
work; I'd just wonder if there's a more consistent piece of the HTTP headers
that's a bit longer than 3 characters that we could expect to be able to use
in a rule like this.

I don't suppose you've got more data than just the URL in question, do you?

On Mon, Jun 13, 2011 at 9:25 AM, Lay, James <james.lay () wincofoods com>wrote:

> Hey all!
>
> Looking through logs today....have come across:
>
> http://web1.51.la:82/go.asp
>
> Which according to malwaredomains.com is no good.  I was wondering if it
> was feasible or a good idea to even create a rule that would fire on one
> or two offs from the standard port?  I do see that msn.com uses port 81
> for an item:
>
> http://apnxscm.ac3.msn.com:81/CACMSH.ashx?&t=1
>
> These are all blocked anyway, but eh...was curious if this could be a
> worthwhile idea.  Thanks.
>
> James
>
>
> ------------------------------------------------------------------------------
> EditLive Enterprise is the world's most technically advanced content
> authoring tool. Experience the power of Track Changes, Inline Image
> Editing and ensure content is compliant with Accessibility Checking.
> http://p.sf.net/sfu/ephox-dev2dev
> _______________________________________________
> Snort-sigs mailing list
> Snort-sigs () lists sourceforge net
> https://lists.sourceforge.net/lists/listinfo/snort-sigs
> http://www.snort.org



-- 
Alex Kirk
AEGIS Program Lead
Sourcefire Vulnerability Research Team
+1-410-423-1937
alex.kirk () sourcefire com

------------------------------------------------------------------------------
EditLive Enterprise is the world's most technically advanced content
authoring tool. Experience the power of Track Changes, Inline Image
Editing and ensure content is compliant with Accessibility Checking.
http://p.sf.net/sfu/ephox-dev2dev

_______________________________________________
Snort-sigs mailing list
Snort-sigs () lists sourceforge net
https://lists.sourceforge.net/lists/listinfo/snort-sigs
http://www.snort.org