German arms and car parts maker Rheinmetall was hit by a malware attack affecting production at sites in the United States, Mexico and Brazil, sending shares down in early trade.
“Normal production processes at these locations are experiencing significant disruption,” Rheinmetall said in a statement.
Rheinmetall shares, which rose around 50% since the start of the year, were indicated to open 2.9% lower in early Frankfurt trade.
“The regional IT infrastructure is shut down and being rebuilt”, Rheinmetall spokesman Peter Ruecker said, adding the company could not say who was responsible.
Cyber-attacks, especially those which affect producers of critical infrastructure, machinery and armament, are aheadache for European blue chip companies.
France’s AFP news agency reported a series of cyber-attacks on Airbus was conducted via the computer systems of suppliers and security sources suspect a link to China.
In July, German blue-chip companies BASF Siemens and Henkel revealed they were victims of cyber-attacks, confirming a German report which said the likely culprit was a state-backed Chinese group.
Rheinmetall said the IT shutdown was expected to last up to four weeks, with a financial impact of 3 to 4 million euros ($3.27 to $4.36 million) a week.
“We are still able to deliver according to schedule,” Ruecker said.
He said the domain affected by malware was cut from Rheinmetall’s corporate network and only the automotive branch was affected by the attack.