A supply-chain ransomware attack that hit hours before the beginning of a holiday weekend has already affected more than 200 businesses, researchers said. On Friday, information technology company Kaseya sent out a warning of a “potential attack” on its VSA tool, which is used by IT to manage and monitor computers remotely. Kaseya urged customers to shut down their servers running the service. This must be done immediately, the company said, because “one of the first things the attacker does is [shuts off] administrative access to the VSA.” It was unclear late Friday how disruptive the attack might be on U.S. businesses. More than 40,000 organizations use Kaseya products, the company says, which includes VSA and other IT tools.