A refrigeration, heating and air conditioning company from Pennsylvania is reportedly at the heart of the Target debit and credit card security breach. Investigative reporter Brian Krebs, who runs the KrebsonSecurity.com website, reports network credentials were stolen from Fazio Mechanical Services and used for gaining access to Target’s system. Company president Ross Fazio has confirmed the US Secret Service has been to his company’s offices, while Target officials will not comment on the report. Krebs reports the HVAC company has worked at several Target stores and those of other retailers. Information from up to 40-million Target customers was stolen between November 27th and December 15th, but Target later acknowledged that additional information from up to 70-million customers was stolen in a separate breach. Target CFO John Mulligan appeared before Congress this week and announced that the company is investing $100-million to improve security, including the adoption of updated Chip-and-PIN credit card technology.