The huge hacking attack against Home Depot’s payment systems could turn out to be the biggest breach of any retailer’s data so far. The company confirmed the data break-in but did not say how many credit and data cards are affected. The total could be as much as 60 million, according to several experts. That would be far more than the total number of cardholders impacted by the breach at Target stores. There is no evidence that any debit card pin numbers were compromised, but according to security reporter Brian Krebs, who first wrote about the breach last week, “multiple financial institutions … are reporting a steep increase over the past few days in fraudulent ATM withdrawals on customer accounts.” The data breach went undetected for six months until banks and law enforcement agencies alerted Home Depot.