By Jim Finkle BOSTON (Reuters) – The U.S. government on Thursday provided merchants with information gleaned from its confidential investigation into the massive data breach at Target Corp, in a move aimed at identifying and thwarting similar attacks that may be ongoing. Its a shame this report wasnt released a month ago, said Dmitri Alperovitch, chief technology officer of the cybersecurity firm CrowdStrike. It has not been forthcoming. No. 3 U.S. retailer Target disclosed the theft of some 40 million payment card numbers and the personal data of 70 million customers in a cyber attack that occurred over the holiday shopping season. Neiman Marcus last week said that it too was victim of a cyber attack, and sources have told Reuters that at least three other well-known national retailers have been attacked.. The document noted that an underground market for malicious software to attack point-of-sale, or POS, terminals has flourished in recent years.