U.S. correctional facilities use programmable logic controllers to control doors and manage security, which makes them vulnerable to a Stuxnet-type worm, according to a research white paper.
Ever since details on the Stuxnet virus began to emerge, security experts have been waiting for the other shoe to drop. Would another worm like it strike? And if so, where?
A team of researchers says it has identified one potential vulnerability: U.S. prisons, which use programmable logic controllers (PLCs) to control doors and gates and manage security functions such as video systems, alarms and intercoms.
In a white paper published July 31, the researchers say a Stuxent-like attack could conceivably be used to open doors and gates or to prevent doors from being opened for a short time, leading to possible scenarios that include escape, chaos, murders and assassinations, or allowing something to be brought into a prison.
One reason Stuxnet worried security experts is the prevalence of PLCs in industrial control systems, including factories and pipelines for oil, gas and water — and, it turns out, prisons.
Stuxnet is a sophisticated worm with a specific purpose — to attack weaknesses in Siemens PLCs used for centrifuges at Iran’s uranium enrichment facilities. The worm managed to disrupt the centrifuges’ operations, causing Iran to replace at least a quarter of them, according to a 2010 report by the International Atomic Energy Agency.
Stuxnet has been called the first cyber weapon because of its ability to inflict physical damage, which has raised concerns about whether another similar worm, or a Stuxnet variation, would be used to attack critical infrastructure systems.
That led the researchers — security engineer John Strauchs; his daughter Tiffany Rad, president of ELCnetworks; and information security consultant Teague Newman — to consider prisons. PLCs are used in large prisons, penitentiaries and jails throughout the United States; only small jails don’t use them.
PLCs typically automate basic functions and use simplistic programming languages such as Ladder Logic that make them easy to exploit, the researchers write.
“For example, everyone on this research team was able to put together a PLC exploit in only a few hours,” they write. They also say that other exploits are publicly available on the Web.
And, in contrast to Stuxnet, attacks on these PLCs need not be so precisely designed.
“By accessing the loaded libraries of the software that control, monitor or program the PLCs, we believe we have found an attack vector that is not vendor-specific,” they write. “Once compromised, it is possible to manipulate the physical state of anything connected to the PLC — such as the lock state of doors — and it is also possible to suppress any notifications or alarms that are delivered or derived from the PLC.”
As part of Supervisory Control and Data Acquisition (SCADA) systems, PLCs typically are not connected to the Internet. But that didn’t stop Stuxnet, which spread via removable media and, although it was designed for a particular job in Iran, turned up in tens of thousands of systems worldwide.
Although the researchers were able to write PLC exploits easily in a lab environment, Strauchs told Security Management’s Carlton Purvis that attacking a prison system would still require some sophisticated hacking.
But the hardware required would cost only about $500.
If no one deals with the problem — the report includes recommendations, including patching PLC software and limiting the use of physical media — someone will exploit the weakness sooner or later, Strauchs told Purvis.
And the potential threat expends beyond prisons. “A logical conclusion to this research is that our findings do not only pertain to PLC and SCADA vulnerabilities in correctional facilities, but in any high-security location that uses these technologies,” the researchers write.
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