By Nikolaj Skydsgaard

COPENHAGEN (Reuters) – Danish train cyber attack: A major breakdown of Denmark’s train network during last weekend was the result of a hacker attack on an IT subcontractor’s software testing environment, Danish train operator DSB said on on Thursday.

“We were contacted by our subcontractor who told us that their testing environment had been compromised by criminal hackers,” DSB’s chief of security, Carsten Dam Sonderbo-Jacobsen, told public broadcaster DR.

“It hasn’t targeted infrastructure or DSB, it was economic crime,” Sonderbo-Jacobsen told Reuters, adding that it was not clear who was behind the attack, but that investigations were ongoing.

While not a direct attack on DSB, the attack prompted subcontractor Supeo to shut down its servers, which in turn affected locomotive drivers’ ability to operate the trains for several hours on Saturday, according to DR.