Kind of sounds funny in today's Information Technology context, doesn'tit? However, it should at least sound familiar to many of us in the ITsecurity realm. We've been following these practices for years, afterall.
The problem is that it's too late. We have no perimeter to secure, nomatter how hard we try to convince ourselves that we do.
Perhaps you're not convinced. Perhaps you think I'm just spewing fear,uncertainty, and doubt (aka FUD) like so many do these days. Well, let metry to convince you:https://o1.qnsr.com/log/p.gif?;n=203;c=204660766;s=9477;x=7936;f=201812281312070;u=j;z=TIMESTAMP;a=20392931;e=i
Just as software developers came up with SOAP to get around ourfirewalls, they've come up with a whole class of software that opens andretains network connections to external systems. These include desktopinstant messenger applications, many Voice over IP applications, etc.Notice how popular IM has become in the past few years? Notice howpopular Skype and all the others are becoming?
Take a closer look at how Skype works behind a firewall sometime. On atypical home network router that prevents all unsolicited incomingnetwork connections, Skype runs just fine, even allowing unsolicitedincoming phone calls while the user remains connected to Skype.
The software has circumvented the firewall, folks. It opens and retainsan active network connection out to the Skype infrastructure, whichhappens to be peer-to-peer (P2P). How much do you know about the IM/VoIPsoftware running on all of your desktops? How much do you know about theexternal servers and P2P networks that are required to make theseapplications function?
Blocking those ports at the firewall, you say? Well, your users arepretty smart people. In all likelihood, they disable the VPN clientsoftware and run their own software on their laptops or desktops, andgleefully connect to these services.
I hope you're convinced by now that the perimeter, at the very least, isnot as clear a line as you may have thought it was.
I say there is no perimeter per se; there is just a multitude ofdefensive products and features spread haphazardly throughout ournetworks. That's probably too far to the other extreme, but I think theconcept is not all that far fetched.
I also want to emphatically note that I'm not saying AIM, Skype, and thelike shouldn't be used. Quite the contrary. I love them both, and I'm anavid user of both. The benefits justify their use, to me. Wellconfigured, they can be powerful business and personal tools.
My main point is that our notion of a security perimeter is at bestantiquated. At worst, it's a dangerous way of thinking.
Until and unless we concentrate our security efforts on the software, allof the security perimeters we devise will be swept aside. We cannotafford to presume that our security perimeter products will protect usagainst bad software -- no matter how much we've paid for them.
The status quo today is that a security vulnerability in some basicapplications can punch right through our 'perimeter' and send us ITsecurity folks scrambling to put out yet another fire.
That doesn't instill me with much confidence, and I hope it doesn't foryou either.
Kenneth van Wyk, a 19-year veteran of IT security, is the prinicpal consultant for KRvW Associates, LLC. The co-author of two security-related books, he has worked at CERT, as well as at the U.S. Department of Defense.