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Recently, David Litchfield asked me to help him out a bit with a =
research project he was working on by having me set up a network capture =
in my DMZ to log SQL Slammer attacks.=A0 I don't publish any services =
here at my Santa Cruz facility (meaning there are no required inbound =
protocols and no references in DNS anywhere) so I figured it would be =
nice "quiet" circuit to use for testing.=A0 I basically port-forwarded =
UDP 1434 to a laptop in my DMZ running NetMon3 also filtering for UDP =
1434.=A0 After about 4 days of running NetMon, I had captured almost 30 =
(verified) random SQL Slammer attacks.=A0 What I found interesting was =
that every single one of them was sourced in China (all from different =
addresses).=20
=A0
Now, it's not my intent to start some geopolitical debate here, but I've =
long heard about how some people would block entire countries at the =
border in order to obviate issues with malicious traffic.=A0 There are =
obviously some issues with this (both from a technical and potential =
customer standpoint) so I set out to do a bit of research on my own.=A0 =
First thing I found out was that if one does decide to block entire =
countries, that it's going to be a bit of work from a rule =
standpoint.=A0 Sure, if I wanted to block all of China I could block =
APNIC, but that would block WAY more than I would want.=A0 So I set =
about finding a good resource for country-by-country IP ranges.=A0 =
Fortunately, Wade Alcorn, one of my colleagues at NGSSoftware turned me =
on to one that seemed pretty decent (there are a few around, though).=A0 =
But finding the resource was just the beginning...=A0 The list I got =
included 234 countries, comprised by almost 100,000 records of IP =
ranges.=A0=A0=20
Making a firewall rule to block China, for instance, would require =
entering in almost 600 IP ranges - so the "manual" route was clearly =
out.=A0 The thing is, I just didn't want to block countries without more =
research, so I needed a way to gather some statistics first.=A0 Enter =
ISA Server - as many of you know, I'm a big fan of ISA - it's a true =
enterprise security product with great scripting capabilities, so I set =
to work creating an automated method by which to create computer sets in =
ISA for each country.=A0=A0 Basically, I created a SQL database and =
loaded all the records into it - I then wrote a little COM app to reach =
out and grab the data by countries, create the sets in ISA, and loop =
through the different ranges of IP's to add them to the set.=A0 It =
worked great.
=A0=20
This accomplished two things - one, I now have full detailed computer =
sets for each country to do with as I please.=A0 Secondly, I have an =
excellent way of producing detailed reports for traffic analysis in ISA- =
this was key.=A0 With data collection points set up at different places =
around the world, I was able to capture 3.1 million inbound connection =
attempts.=A0 The results were quite interesting.=A0 While China still =
led with connection attempts overall, it was interesting to see that =
Canada was a close second.=A0 However, while China's traffic consisted =
of SQL Slammer, HTTP, SMTP, probes for GhostProxy, etc, almost all of =
Canada's traffic was MESSENGER spam (UDP 1026,1027,1208).=A0 The world =
leader for HTTP was Brazil, strangely enough.=A0 Now, all of this will =
change based on who and where you are, and the types of services being =
offered.=A0 For example, I only got 5 SMTP connection attempts to my =
cable modem in a week, but my ISP in BM got hundreds of thousands =
(understandably) in the same time period.=A0 I'll whip up some cool =
reports for what I found and post them once I get some more data in from =
different collection points, but the valuable outcome of the project was =
the creation of these individual country-by-country Computer Sets for =
ISA.
Beforehand, I had no real way of easily and effectively reporting on =
traffic patterns by source country.=A0=A0 Whether you can or can't block =
entire countries is your business, but at least this affords someone an =
easy way of doing research.=A0 You may not be able to (or even want) to =
block HTTP from China, but you very well may want to block SMTP - with =
ISA and computer sets, you can easily do this.=A0 Even if you don't =
block anything at all, you can use the sets to get rich reports of what =
kind of traffic your are getting from a particular country.=A0 While the =
validity of the practice of blocking entire countries (or particular =
protocols for that matter) may be up for debate, you now at least have =
the option to make your own decision based on factual information - to =
be sure, you've always been able to do this obviously, it's just been my =
experience that maintaining rule lists by country/protocol has been =
quite difficult and time consuming.=20
I've exported every countries entire list to ISA 2006 .XML format, and =
have posted them on the HoG site for community use.=A0 Since I've =
automated the Set creation process, I'll be updating the sets each month =
or so to ensure that changes are processed correctly.=A0=A0 I would like =
to thank NGSSoftware for purchasing the required business services to =
receive the updates - their donation makes it possible for me to give =
you updated sets for free.=20
A full list of all countries' ISA .xml for ISA 2006 is available here:
http://hammerofgod.com/download/ISASets/
The first file is a zip of all countries is you want that one.=A0 Go =
nuts!
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