The Firewall is the Most Successful Technology
Roger Grimes and I have engaged in a very interesting conversation around the necessity and value of firewalls. Yesterday I took issue in my blog post with Roger's initial claim that the firewall is dead. In response, Roger continues his argument in his post, The Firestorm over Firewalls.
Roger seems to have capitulated the argument on ineffective management and instead doubled down on two core points:
- 99% of all attacks are client-side initiated and the firewall is ineffective at protecting against these attacks
- The fact that the industry is not more secure is proof that the firewall is worthless
I still take significant issue with the argument that 99% of all attacks are client-side and Roger's proof that anti-virus vendors block a lot of stuff is not compelling to me. Remember firewalls block a lot of stuff too with billions of logs of dropped traffic generated every second world-wide. Neither of these points is sufficient to make or dispel the 99% claim. The Verizon Data Breach Investigations Report I referenced is also not perfect, as Roger points out, as it only covers a minority of all attacks worldwide. But it is the best source I am aware of, so I think it is still worth referencing. And pointing to a sample graphic ( on page 8 ) meant to describe a documentation standard as proof that client-side attacks are responsible for all breaches is not very compelling either. Especially since it was not written to support this point in any way. However, even if we do acknowledge Roger's proof graphic on page 8, take a look a the paragraph describing it that claims an egress filter (firewall) could have prevented the breach and it seems to dispel Roger's obituary of the firewall.
But let's set statistics aside. I imagine there are plenty of other people who can more credibly respond to Roger's unsubstantiated claim about 99% of attacks are client-side. And, I don't mean to argue that client-side attacks are not an issue, I simply mean to claim they are not the only issue.
Instead, I would like to hypothetically accept Roger's postion that 99% of all successful attacks are client-side. I would argue this change in attack vectors through the years strengthens the case that a well-configured firewall is an effective security control. It is a matter of attackers coming in through the open window instead of the closed door. The growth in client-side attacks suggest the direct attack is being successfully thwarted by the firewall and less effective solutions are being exploited.
The great thing about a firewall is that it employs a positive security model where only what you decide to allow is permitted and everything else is denied. When managed well, it makes it a great security solution. In contrast, malware detection and anti-virus software employ a negative security model where everything is allowed and only known bad attacks are denied. This creates a horrible cat and mouse game that the attackers seem adept at winning by staying a step ahead of the latest signatures. Which begs the question, if Roger's argument is that client-side attacks are the real problem and the fact that we still have security problems is justification to kill a technology, why does he pick on the firewall. Shouldn't he instead have called anti-virus or anti-malware or some other client-side technology dead instead? The firewall, according the Roger's own logic, is the one technology in the game that is working.
The firewall isn't dead. In fact, I think Roger's arguments strengthen the case the firewalls are working. Are they perfect, no. Are they sufficient to solve all the security problems, no. Should we get rid of them because they are not perfect, NO!
And this gets to the heart of the matter: the fact that there remain security issues in information technology is not a matter of one technology working or not. It is not justification to call an effective technology dead because it doesn't solve everything. When effectively managed, the firewall is a very effective security solution. Additional capabilities in NG Firewall technology continue to make it a relevant and central part of a security solution. It should not be considered THE solution, but it certainly shouldn't be discounted either.