The attack itself was reported to have brought down a file server at Kojima Industries on Saturday night. The server in question was found to contain a computer virus and some kind of threatening message in English.
As a result, Kojima has stopped its own production, and because Toyota plants operate with very minimal inventory, relying on a four-tiered network of some 60,000 suppliers, the carmaker has also been forced to halt production.
Toyota has said that it is aiming to restart production very soon. Some 13,000 cars have already been taken out of production as a result of the shutdown.