Even 'Regular Cybercriminals' Are After ICS Networks

Contrary to what some might perceive, state-backed groups and advanced persistent threat (APT) actors are not the only adversaries targeting industrial control system (ICS) environments.

A recent honeypot project conducted by security firm Cybereason suggests that ICS operators need to be just as concerned about ordinary, moderately skilled cybercriminals looking to take advantage of weakly secured environments as well.

"The biggest takeaway is that the threat landscape extends beyond well-resourced nation-state actors to criminals that are more mistake-prone and looking to disrupt networks for a payday," says Ross Rustici, senior director of intelligence services at Cybereason. "The project shows that regular cybercriminals are interested in critical infrastructure, [too]."  

Cybereason's honeypot emulated the power transmission substation of a major electricity provider. The environment consisted of an IT side, an operational technology (OT) component, and human-machine interface (HMI) management systems. As is customary in such environments, the IT and OT networks in Cybereason's honeypot were segmented and equipped with security controls that are commonly used by ICS operators.

To lure potential attackers to its honeypot, Cybereason used bait such as Internet-connected servers with weak passwords and remote access services such as RDP and SSH enabled. But the security firm did not do anything else besides that to promote the honeypot.

Even so, just two days after the honeypot was launched a threat actor broke into it and installed a toolset designed to allow an attacker and a victim use the same access credentials to log into a machine via Remote Desktop Protocol (RDP). The toolset, commonly found on compromised systems advertised on xDedic, a Russian-language cybercrime market, suggested that the threat actor planned to sell access to Cybereason's honeypot to others.

The threat actor also created additional user accounts on the honeypot in another indication that the servers were being prepared for sale to other criminals. "The backdoors would allow the asset's new owner to access the honeypot even if the administrator passwords were changed," Cybereason said in a blog describing the results of its honeypot project.

Cybereason deliberately set up the honeypot with relatively weak controls so it would take little for the attacker to break into it by brute-forcing the RDP, Rustici says. The skill level to prepare the server for sale was also fairly rudimentary and could have been accomplished by a high-level script kiddie.

Slightly more than a week after the initial break-in, Cybereason researchers observed another threat actor connecting to the honeypot via one of the backdoor user accounts. In this instance, the attacker was focused solely on gaining access to the OT environment. The threat actor's scanning activities and lateral movement within the honeypot environment was focused on finding a way to access the HMI and OT environments.

The threat actor showed no interest in activities such as using the honeypot for cryptomining, launching DDoS attacks, or any of the other activities typically associated with people who buy and sell access to compromised networks.

The adversary's movements in the honeypot suggested a high degree of familiarity with ICS networks and the security controls in them, Cybereason said. At the same time, the attackers, unlike more sophisticated adversaries, also raised several red flags that suggested a certain level of amateurishness on their part.

"The way they operated makes us think this group was a mid- to high-level cybercrime group," Rustici says. "Based on their capabilities, it is likely they were either trophy hunting to improve their reputation or looking for a ransom payday."

The data from the honeypot project shows attackers have a new way of sourcing ICS assets, Cybereason noted. Rather than select, target, and attack a victim on their own, adversaries can simply buy access to an already compromised network.

The threat group that purchased access to the honeypot also lived entirely off the land for lateral movement and for scanning for systems with access to HMI and OT systems, Rustici says. "They never uploaded a tool to the network," he noted.

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