Deep Packet Inspection

This blog is the last one from me as a member of the company that manufactures and sells Tofino Security products. Joann Byres (Tofino co-founder and Belden Vice President) and I are retiring from the Tofino Security group at Belden effective January 30, 2015.

Author Mike Miclot

Nobody likes the job of replacing a good team member when they retire. Yet, that is the job the manufacturing industry is faced with as a trusted component of the industrial application ecosystem steps down from active duty. That component is the Windows XP operating system (OS), a workhorse of a product that is pervasive in factories, energy facilities and many critical infrastructure systems around the world.

Author Mike Miclot

On the eve of April 8, Microsoft retired support for the Windows XP operating system (OS) – leaving millions of Windows XP users susceptible to accidental and deliberate security issues. Though the retirement had been long planned and with fair warning, industrial network users are just beginning to comprehend the ramifications.

You have likely never worried about the possibility of a high school geek doing some programming that affects your home water quality. Well, neither had I until I learnt that some municipal networks have no security between the network their schools use and the one that runs their water/wastewater facility.

One of the major differences between industrial networks and enterprise networks is that industrial networks are typically managed by engineers or technicians. Now engineers are experts at making good product, designing control loops and so on, but they are not IT security wizards. That's the reality, and it means that security products that "just work" reliably and safely with automation systems are going to be more effective in actually delivering security than products that don't.

In last week’s Practical SCADA Security blog, I discussed how the new vulnerabilities discovered in DNP3 SCADA masters are carving big holes in the NERC’s concept of the Electronic Security Perimeter (ESP).

In a recent blog article – Chicken, Egg, and Chicken Omelette with Salsa – Dale Peterson is squawking like a rooster. Nothing new, but this time his message is scrambled. He once again referred to me as a SCADA Apologist, though this time he also labeled me the “salsa” that accompanies a chicken omelette.

Following on from Eric Byres’ discussion of Deep Packet Inspection (DPI), this article discusses a second and equally important aspect of effective firewall security referred to as “stateful inspection”.

Deep Packet Inspection (DPI) is important for the future of SCADA / ICS security - and in this article I explain why.  

DPI SCADA Security: Reviewing the Basics

In Part 1 of this series I explained DPI technology in detail. To review, the traditional IT firewall examines the TCP/IP and Ethernet headers in the network messages it sees. It then makes decisions whether to allow or block a message based on this limited information.

I have talked repeatedly about something called Deep Packet Inspection (DPI) and why it is so important for SCADA / ICS security (for example, see Air Gaps Won’t Stop Stuxnet’s Children). The trouble is, I have never described what DPI actually is. So in today’s blog I will back up and explain what DPI firewall technology is all about.

Over the past month, there has been no shortage of reports on how Stuxnet is attacking the Iranian Nuclear Program. Unfortunately, good advice on what exactly Industrial Control System (ICS) owner/operators can do to protect themselves against Stuxnet (and its future offspring) is in short supply. In fact much of what passes as technical guidance is either too IT-focused or simply wrong.

Over the years I have been asked by a number of control engineers, “Our IT dept says we have VLANs, so why do I need a firewall?”

Back in the mid-90s, I was a big supporter of Virtual Local Area Networks (VLANs) for security. Unfortunately, I have seen so many issues with this technology that I no longer believe it provides effective security.