A public utility in the U.S. was compromised after attackers took advantage of a weak password security system, according to a U.S. Department of Homeland Security team that studies cyberattacks against critical infrastructure.
The utility's control system was accessible via Internet-facing hosts and used a simple password system, wrote the Industrial Control Systems Cyber Emergency Response Team (ICS-CERT) in a report on incidents covering the first quarter of this year.
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The utility, which was not identified, was vulnerable to a brute-force attack, where hackers try different combinations of passwords until the right one is found. An investigation showed the utility was attacked before.
"It was determined that the systems were likely exposed to numerous security threats, and previous intrusion activity was also identified," ICS-CERT wrote in the report.
The U.S. government has long warned that critical infrastructure such as power and water plants are at risk of cyberattack, as many of their IT systems have not been rigorously audited for vulnerabilities and configuration mistakes.
ICS-CERT warned that it is easy for hackers using search engines such as Google and SHODAN to find Internet-connected control systems "that were not intended to be internet facing."
The report described a second cyberattack but did not specify what type of organization was affected.
In that instance, an Internet-connected control system that operated a mechanical device was accessed by an attacker using a cellular modem. The access has been gained using a SCADA (supervisory control and data acquisition) protocol, the team wrote.
"The device was directly Internet accessible and was not protected by a firewall or authentication access controls," ICS-CERT wrote.
The attacker appears to have struck at just the wrong moment. The mechanical device happened to be disconnected from the control system for scheduled maintenance, the team wrote.
In the first quarter of this year, ICS-CERT advised 20 energy, water, nuclear and transportation utilities on identifying vulnerabilities and how to improve their cyberdefenses, the report said.
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