The cybersecurity firm Mandiant confirmed Friday that in early June the California Water Service was hacked. Cal Water serves nearly 2 million Californians, including some areas of Livermore and Stockton.
According to a statement from the utility's Director of Corporate Communications, Yvonne Kingman, Mandiant found the attack was limited to a small number of accounts on two outside vendor platforms.
That included one customer's account that was accessed using stolen login credentials. The investigation found no evidence the attacker reached Cal Water's internal business systems or the operational systems controlling water treatment and delivery.
Cyberattacks on U.S. water systems have been rising, with federal agencies repeatedly warning utilities to shore up their defenses.
The company says it's continuing to work with state and federal partners to secure its systems.
