An alchemists view from the bar

Network Security Alchemy

Defying the all or nothing approach to network security

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I am writing this while sitting in a hotel bar feeling way over-dressed for an occasion. I have just arrived at the Black Hat Europe 2008 conference in Amsterdam, and after being in meetings earlier today, haven’t yet had time to put on some more “relaxed” clothing to fit in with everyone else around me.

Sipping my Heineken, obviously served the continental way (thats with a quantity of head that instinctively makes you check for a measurement line), I was trying to catch up on email when I came to notice another overlooked parallel between IPS deployment design and the real world. Ditching the over-spilling inbox, I felt compelled to write about it.

A common challenge I encounter when working with organizations to help design intrusion monitoring and prevention strategies, is one of balancing unrealistic objectives with all too realistic budgets. I guess that there’s no shock there as its a far from a new problem, however I find that for me it becomes less frustrating once I manage to get a few important concepts across to the client.

Before I meet with those who are in possession of the organizational and technical information required to help deploy an IPS, it’s common for one of my “sales-guys” to say in an upbeat way “Don’t worry Leon, this design won’t take you long, they emailed me a network diagram! I have already half-specced the solution myself!”, The look in their eyes as they rub their hands together is one of elation as they count and re-count how much their design will cost.

I find that there is commonly an all-or-nothing approach unique to network security, this forces people to rarely see a middle ground of achievability. This is probably best manifested when I see the infamous network diagram, now modified to include an IPS appliance on every network link on the page. I don’t want to poke fun solely at my sales-guys for the occasional over optimistic deployment idea, I see similar designs from other network security venders all the time.

I have never been shown a network diagram that allows me to immediately design a decent IPS deployment. People think of a network IPS as its name suggests, a network device, however the function it provides operates at network, service, application and organizational levels. The normal network map that I initially get shown is one of routers, switches, firewall’s etc, it never presents me with worthwhile information about business objectives, how data is designed to move around the ether. Where do critical business services exist and barriers of trust drawn?

The all-or-nothing approach to device placement commonly results in a great number inline devices between every link that you can find, it costs a bucket load of cash and probably wont actually meet a goal of substantially improving security.

So, you may wondering what the parallel is that I felt compelled to write about, so lets jump a little closer to the point. When you plan an IPS deployment, don’t start off with the unobtainable “all-or-nothing” approach. Start with a plan that reflects network data flow as of now, and then try to meet achievable objectives that have been formally defined. This process also indirectly addresses the below common objections I hear against IDS and IPS as a technology.

“To do this right, I need to place down way to many devices. Too much cost in purchasing, and management effort”

“I cant put IPS everywhere so what’s the point of monitoring at all”.

The bar that I am sitting in has somewhere in the region of sixty people, they are all going about their business, chatting away and enjoying many creatively poured glasses of Heineken. It is impossible for me to monitor what everyone is discussing, especially without interruption, but is it impossible for me, a single monitoring point, to overhear something valuable?

I wasn’t purposely trying to eavesdrop,  but I couldn’t help but overhear an interesting conversation coming from the table next to me. The details of what was said is irrelevant for my point, but now that I have heard it I feel that I’m in a much better situation that I was before. I can use this newly found knowledge to be more intelligent about things. This is just the same as using the intelligence provided from a single network security monitoring device, we just need to make sure that we understand the scope of what it provides.

In the UK we are famously big users of Closed Circuit Television (CCTV), it provides an immensely valuable resource of audit data and crime detection. It is impossible to monitor the whole country with CCTV as the cost of cameras and the required of management effort grows beyond a line of what is worth-while. This line of what can be achieved and managed is also visible at an organizational level, It is unlikely that your whole office is monitored with CCTV, but there may well be a camera or two above important doors.

In just the same way that I can over hear a conversation or a well placed CCTV camera can record an interesting event, strategic placement and planning of a network monitoring device can provide data about specific assets that concern the user. A network IPS is essentially an access control device, and assuming you select a good one, extremely flexible. Operation of these devices fall into one of two camps, Detective controls, like a CCTV camera and preventative controls, like an automatic door. As you can imagine, the most valuable deployments provide a mix of these two controls at relevant locations.

Remember that if you decide to operate the network without audit and detective controls in place, you will never discover anything. With a good design that can actually deliver achievable, protection and monitoring in specific areas, this gives you one hell of a better chance to protect your organization than leaving your head stuck in the sand monitoring nothing.

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Written by leonward

March 10, 2008 at 5:58 pm

Posted in Security

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