Southern Water reports £4.5M cost from ransomware attack

Southern Water, a major UK water supplier, has revealed in its annual report that a cyberattack in February 2024 resulted in £4.5 million ($5.7 million) in expenses.

The company provides water services to 2.7 million customers and wastewater services to over 4.7 million across Kent, Sussex, Hampshire, and the Isle of Wight. Each day, Southern Water supplies 570 million liters of water through its 13,973 km network and manages 1,522 million liters of wastewater via a 40,058 km sewer system.

The breach, which was disclosed by the company about a year ago, was attributed to the Black Basta ransomware gang, a cybercriminal group known for targeting critical infrastructure. At the time, Southern Water assured that the incident did not impact operations, financial systems, or customer-facing platforms.

However, according to a financial report, the cost of dealing with the attack reached £4.5 million (page 98).

“In February 2024 we announced that data from a limited part of our server estate had been stolen through an illegal intrusion into our IT systems. We engaged external cyber security experts and legal advisers in response, as well as contacting anyone whose personal data may have been at risk. We have incurred £4.5 million in responding to this exceptional incident during the year.”

To mitigate future risks, the company says it has hired cybersecurity experts to monitor the dark web for any leaked data related to them or their customers. So far, no such leaks have been identified, reports Bleeping Computer.

When asked by The Register whether the company made a payment to the hackers, a Southern Water spokesperson reiterated previous statements, without providing further clarification.