A report issued by the Department of Homeland Security says a previously unseen malicious software program they are calling Mozart was used in the security breach at Atlanta-based The Home Depot Inc.

The report draws on information gathered by the Secret Service, which is investigating the breach, The Wall Street Journal reported early Thursday. Officials say it appears the software was customized to attack Home Depot’s systems, the WSJ said. The phrase ‘Mozart’ was in the malware’s code…