ICS/OT Cal Water Finds No Evidence of OT Activity After Hackers Claimed They Could Disrupt Water Supply Mandiant has helped the California water utility investigate the cyberattack launched by Iranian hacker group Handala. By Eduard Kovacs | June 25, 2026 (8:07 AM ET) Flipboard Reddit Whatsapp Whatsapp Email The investigation conducted by California Water Service (Cal Water) into the recent cyberattack claimed by the Iranian hacker group Handala found no evidence of activity in the water utility’s operational technology (OT) environment. Handala , which claims to be a hacktivist collective but is widely believed to be a front for Iranian government hacking operations, said it could have disrupted the water supply after gaining access to Cal Water systems but decided not to do so. The statement suggested that the hackers had gained deep access to industrial control systems (ICS). The threat actor leaked 5 GB of data allegedly taken from Cal Water systems. Cybersecurity analysts discovered personal information in the published files and found evidence that a customer billing system and an internal application may have been compromised. SecurityWeek ICS Cybersecurity Conference Heads to Nashville for Special 25-Year Anniversary Edition Cal Water, one of the largest investor-owned water utilities in the United States, has hired cybersecurity experts, including Google’s Mandiant unit, to assist with the investigation into the cybersecurity incident. In a statement to SecurityWeek , Cal Water said, “Based on its investigation, Mandiant has confirmed that the threat actor activity was limited to unauthorized access to a small number of specific user accounts within two third-party service provider platforms.” Advertisement. Scroll to continue reading. It added, “Mandiant did not identify evidence of threat actor activity in Cal Water’s internal information technology or operational technology environments.” “The investigation determined that the threat actor accessed one active customer’s online Cal Water account using stolen user credentials. The customer account did not provide access to the billing system, and no payment information was compromised. The threat actor also accessed an external, third-party web site related to a GPS location correction tool; however, the website does not contain any confidential or sensitive information.” The organization concluded, “We appreciate the collaboration and support our state and federal government partners provided throughout the investigation, and we will continue to work to maintain the security of our systems and data from malicious actors.” The water sector continues to be a prime target for threat actors due to its heavy reliance on legacy systems and often inadequate cybersecurity measures. Related : Lantronix Serial-to-IP Converter Flaw Exploited in Attacks After OT Threat Warning Related : Accenture to Acquire Majority Stake in Dragos, All of runZero, NetRise in $4.1 Billion OT Cybersecurity Push Related : Siemens Says Desigo CC Files Flagged as Malware by Security Engines Written By Eduard Kovacs Eduard Kovacs (@EduardKovacs) is senior managing editor at SecurityWeek. He worked as a high school IT teacher before starting a career in journalism in 2011. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering. Daily Briefing Newsletter Subscribe to the SecurityWeek Email Briefing for the latest cybersecurity threats, trends, and expert insights. 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