Defending your safety system

Some of the things the industry learned from Stuxnet were modern industrial control systems/SCADA systems are highly complex and interconnected

07/08/2011


In this era of living with sophisticated attacks like Stuxnet, the main thing manufacturers have to do to ensure their systems remain protected is to look at the vital area that will keep the system up and running.

“You need to secure that last line of defense,” said Eric Byres, chief technology officer at Byres Security, during his talk entitled “How Stuxnet Spreads, a study of infection paths in best practice systems” at the Honeywell User Group conference in Phoenix, AZ . “First and foremost that is the safety system.”

 

Stuxnet was one nasty worm, Byres said. The hysteria caused by the worm showed users were purely reacting and not really thinking about how they can build a solid defense that protects the control system.

The big news when the world first became aware of Stuxnet was people believed the worm entered control systems via a USB key. While that may have happened, it doesn’t seem right that users would ban the use of USB drives. They do serve a quality purpose.

The worm did infect some 100,000 computers and infected at least 22 manufacturing sites, which Byres actually believes was more around the 50 number.

One of the shocking thoughts about Stuxnet was the worm was able to penetrate and damage a nuclear site, which has some of the toughest security in any industry. What happens, Byres asked, when another worm comes around and takes over a less secure environment?

The odd part of the entire attack was Siemens does have a solid layered security architecture in the systems targeted for attack.

As mentioned the attack could have happened on a USB stick, however it could also have come as a result of infected project files, transmitted in an email, an infected laptop among other possibilities.

“If someone wants to put a virus on your site, they will be able to,” Byres said. “It depends on what you do with that afterward is what is important. There was so many ways it could spread.”

Some of the things the industry learned from Stuxnet was modern industrial control systems or SCADA systems are highly complex and interconnected; there are multiple pathways; you have to assume an air gap is unrealistic; focusing security on specific obvious pathways is not a good idea, and users have to complete a simple overall holistic view of the system, Byres said.

The thing is about the attack is the world of attackers have not found a new industry and area that is ripe for attack. “Security experts” can go into systems and find their vulnerabilities and Byres said they are selling them on the Internet for up to $2500.

There were quite a few scary aspects to the worm, but one that Byres said was frightening was Payload C. That was code that never loaded, but Byres believes the creators earmarked that payload for the safety system.

If it went after a safety system, you take on the last line of defense and that could mean the end of the plant and the surrounding area.

“If you combine safety and the control system you are doing the attacker a favor,” Byres said. You have to be able to separate the systems somehow.

Things are not all glum, if users learned lessons from this attack they will be ready for the next one, because there will be a next one, Byres said.

“We live in this perfect world where we can communicate all over the place; we just forgot to manage it.”



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