A potentially serious denial-of-service (DoS) vulnerability affecting some Mitsubishi Electric automation controllers can allow hackers to disrupt the production process in an industrial organization, experts have warned.
The flaw, discovered by a researcher at industrial cybersecurity firm SCADAfence and reported to Mitsubishi in late February, was described by the vendor as an uncontrolled resource consumption issue that allows an attacker to cause the Ethernet port to enter a DoS condition by sending it specially crafted packets, in bursts, over a short period of time.
The vulnerability affects Mitsubishi’s MELSEC iQ-R series CPU modules, including R00, R04 and R08, and the RJ71EN71 Ethernet interface module. The vendor has released firmware updates that should address the flaw for several of the affected modules and plans on releasing patches for the remaining products “soon.” In the meantime, the company recommends a series of mitigation steps.
Ofer Shaked, co-founder and CTO of SCADAfence, told SecurityWeek that the impacted controllers are used across all industries. The affected products include safety controllers, high-speed motion controllers used in robotics and other motion-oriented applications, and process CPUs that can be used to monitor and control physical processes in sectors such as critical infrastructure and manufacturing.
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“This vulnerability is dangerous to industrial environments, because unlike other DoS attacks, it doesn’t only crash the network interface controller. We’re also talking about crashing the main CPU, which stops the entire production process and loses the current state of operation,” Shaked explained. “An unauthenticated remote attacker over the network, can stop your entire production, in a way that requires physical intervention (rebooting the PLC, recalibrating, restarting any production process).”
Shaked warned that the vulnerability is easy to exploit. Exploitation only requires network access to the targeted device, but no special privileges or user interaction are needed to launch an attack.
“Once an attacker has access to the network, they can run a simple Python script and crash the PLC CPUs remotely. All they need is network connectivity. The script takes less than a second to crash the CPU,” he explained.
He added, “[Exploitation] doesn’t require any advanced knowledge in process automation. The attacker has to send 2 bytes of payload multiple times in burst to the PLC, and the PLC will crash.”
An advisory published by the U.S. Cybersecurity and Infrastructure Security Agency (CISA) assigns the vulnerability a CVSS score of 5.3, which puts it in the medium severity category. However, SCADAfence believes the real CVSS score, based on its impact, is 8.6, which makes it high severity. The company has reached out to CISA in hopes that the CVSS score will be updated in the agency’s advisory.
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