Florida water plant compromise came hours after worker visited malicious site

tried to poison drinking water, security firm Dragos said Tuesday. Ultimately, the site likely played no role in the intrusion, but the incident remains unsettling, the security firm said.

The website, which belonged to a Florida water utility contractor, had been compromised in late December by hackers who then hosted malicious code that seemed to target water utilities, particularly those in Florida, Dragos researcher Kent Backman wrote in a blog post. More than 1,000 end-user computers visited the site during the 58-day window that the site was infected.

One of those visits came on February 5 at 9:49 am ET from a computer on a network belonging to the City of Oldsmar. In the evening of the same day, an unknown actor gained unauthorized access to the computer interface used to adjust the chemicals that treat drinking water for the roughly 15,000 residents of the small city about 16 miles northwest of Tampa.