Vulnerabilities in electronic systems that control prison doors could allow hackers or others to spring prisoners from their jail cells, according to researchers. PLCs are small computers that can be programmed to control any number of things, such as the spinning of rotors, the dispensing of food into packaging on an assembly line or the opening of doors. Two models of PLCs made by the German-conglomerate Siemens were the target of Stuxnet, a sophisticated piece of malware discovered last year that was designed to intercept legitimate commands going to PLCs and replace them with malicious ones.
Stuxnet’s malicious commands are believed to have caused centrifuges in Iran to spin faster and slower than normal to sabotage the country’s uranium enrichment capabilities. Though Siemens PLCs are used in some prisons, they’re a relatively small player in that market. The more significant suppliers of PLCs to prisons are Allen-Bradley, Square D, GE and Mitsubishi. Across the U.S. there are about 117 federal correctional facilities, 1,700 prisons, and more than 3,000 jails. All but the smallest facilities, according to Strauchs, use PLCs to control doors and manage their security systems.
Researchers says the vulnerabilities exist in the basic architecture of the prison PLCs, many of which use Ladder Logic programming and a communications protocol that had no security protections built into it when it was designed years ago. There are also vulnerabilities in the control computers, many of which are Windows-based machines, that monitor and program PLCs.
The vulnerabilities are inherently due to the actual use of the PLC, the one-point-controlling-many. Upon gaining access to the computer that monitors, controls or programs the PLC, you then take control of that PLC. A hacker would need to get his malware onto the control computer either by getting a corrupt insider to install it via an infected USB stick or send it via a phishing attack aimed at a prison staffer, since some control systems are also connected to the internet.
Prison systems have a cascading release function so that in an emergency, such as a fire, when hundreds of prisoners need to be released quickly, the system will cycle through groups of doors at a time to avoid overloading the system by releasing them all at once. Researchers confirms that a hacker could design an attack to over-ride the cascade release to open all of the doors simultaneously and overload the system.
An attacker could also pick and choose specific doors to lock and unlock and suppress alarms in the system that would alert staff when a cell is opened. This would require some knowledge of the alarm system and the instructions required to target specific doors, but researchers explains that the PLC provides feedback to the control system each time it receives a command, such as “kitchen door east opened.” A patient hacker could sit on a control system for a while collecting intelligence like this to map each door and identify which ones to target.
While PLCs themselves need to be better secured to eliminate vulnerabilities inherent in them, prison facilities also need to update and enforce acceptable-use policies on their computers so that workers don’t connect critical systems to the internet or allow removable media, such as USB sticks, to be installed on them.
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