There has long been talk of fears of cyber criminals attacking the power grid. Well, those fears came a little closer to reality this week.

The U.S. Department of Homeland Security's Industrial Control Systems Cyber Emergency Response Team (ICS-CERT) reports malware infected two U.S. power stations in the fourth quarter of 2012.

According to ICS-CERT, the malware was discovered when an employee asked company IT staff to inspect his USB drive after experiencing intermittent issues with the drive's operation. The employee routinely used this USB drive for backing up control systems configurations within the control environment.

The Tainted USB Drive

"When the IT employee inserted the drive into a computer with up-to-date antivirus software, the antivirus software produced three positive hits," the ICS-CERT said in a report. "Initial analysis caused particular concern when one sample was linked to known sophisticated malware."

The conclusion: a handful of machines likely had contact with the tainted USB drive. ICS-CERT immediately examined the machines. Drive images were taken for in-depth analysis. ICS-CERT said it also performed preliminary on-site analysis of those machines and discovered signs of the sophisticated malware on two engineering workstations, both critical to the operation of the control environment.

ICS-CERT blamed one of the infections on a third-party contractor who unknowingly infected systems at a power generation facility after plugging in a USB drive that was infected. That unleashed a crime-ware virus into a turbine control system Relevant Products/Services that spread to about 10 other networked machines.

Stuxnet-Like Attacks?

Dave Pack, director of Labs for the security Relevant Products/Services firm LogRhythm, told us it was too early to tell whether these were targeted Stuxnet-like attacks. Initial reports, he said, indicate they are more likely to be widely available pieces of malware not specifically designed to target supervisory control and data Relevant Products/Services acquisition (SCADA) environments. That said, he added, the malware was still disruptive, in one case delaying a plant restart by approximately three weeks.

"USB drives and removable media continue to be an excellent attack Relevant Products/Services vector for malware," Pack said. "In cases like this, where an ICS/SCADA-like infrastructure Relevant Products/Services is air gapped and removable media must be frequently used to support operations, it's important that organizations include security into their processes and procedures to ensure nothing malicious is inadvertently being introduced into the environment."

In his opinion, removable media used in operations like this should be frequently scanned for malware. What's more, he offered, strict policies should be put in place and enforced to control how the media is stored and used.

"Even with the best policies, procedures and preventive technologies in place, breaches will occur," Pack said. "Having continuous monitoring in place designed to detect anomalous activity indicating that a system or credentials have been compromised can mean the difference between rapid containment and remediation, or catastrophe."