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Check that thumb drive at the door? Seriously?

Where is the line between security efforts that are symbolic, and those that have a real purpose?

July 22, 2011


Dear Control Engineering: I was reading the article about giving your plant a cyber health checkup. The authors say that we should keep an eye on plant visitors. Here’s the quote: “That can include having rules that require visitors to leave USB drives with security guards prior to entering the facility, for example. A strict, comprehensive policy will help outsiders understand the seriousness of a plant’s cyber security culture.” I can understand the idea of not plugging in a laptop, but is the idea of checking thumb drives at the door really necessary, or merely symbolic?

Such a policy is not merely symbolic. Once an individual is in a facility and can reach computers that are on a network, it can be much easier to cause mischief than it is from the outside. Many systems assume, at least to some extent, that if you’re in the building, you are probably friendly. There may also be certain parts of the network that cannot be reached from outside, but can be from an internal wired connection. If a cyber crook sees that an individual has walked away from his or her terminal that is logged into the network, it is an open invitation. That’s like parking your car unlocked with the keys in it and the engine running.

A USB thumb-drive can be programmed with all sorts of scary things, and if it can be put into an open port on the network, it can cause no end of trouble. Just to make that point more clearly, I contacted cyber security instructor Matt Luallen to explain some of the things that are possible. He says:

"USB flash drives may serve more functions than you think. Combine Arduino with a Teensy++ hardware device and now you have USB hardware that can emulate typically trusted devices like a mouse, a keyboard, and furthermore, a storage device. Common operating system security precautions include disabling autorun functionality for external storage mediums, but the Teensy++ hardware can emulate a keyboard thereby bypass this common control. Next, if you are operating in an environment with Windows 7, it natively includes a tool called Powershell. Add a little Arduino and Powershell scripting and now there is access to the host with the credentials of the logged-in user. This script could create an outbound connection to a metasploit shell, an internal HMI modification, or an OPC or PLC login and modification with default credentials. The resulting opportunities are left up to the mind of the attacker as the typical cyber and physical security walls have been evaded, and the only security controls left are represented with the soft-gooey middle of the 'M&M model,' a hard outer shell and soft and gooey in the middle. For more information about this type of attack and others with their associated mitigating controls, check out CYBATI's two day workshop on Critical Infrastructure Control System Cybersecurity at cybati.org."

Convinced?

This is why physical and cyber security have to operate hand in hand. The shed out at the pumping station with the RTU should be kept locked, because if a determined hacker wants to break into the network, that’s a prime path.

While symbolism in safety and security are important to keep people thinking the right way, don’t simply assume that is the only element operating.

Watch a video with Matt Luallen.

Peter Welander, pwelander(at)cfemedia.com