During a US Senate hearing on Tuesday, US Attorney General Eric Holder again confirmed that the Department of Justice is investigating the massive Target hack. "While we generally do not discuss specific matters under investigation, I can confirm the Department is investigating the breach involving the US retailer, Target," Holder said. But the DoJ's search isn't limited to the perpetrators. Holder's testimony included a stern warning for anyone using the stolen customer information for illegal purposes. "We are committed to working to find not only the perpetrators of these sorts of data breaches. but also any individuals and groups who exploit that data via credit card fraud."

Target has said data on roughly 40 million credit and debit cards was lifted during the breach. Hackers managed to infect Target’s retail registers with malware that stole the financial info. 70 million other records containing sensitive customer information like mailing addresses and phone numbers were also stolen in the massive attack. Other retailers have reported similar breaches, and the FBI has warned companies that these sophisticated hacks are likely to continue. To help reduce that threat, the US government has privately shared some methods used by Target's hackers with other major US merchants. "We also will continue enforcing essential privacy protections and other safeguards concerning data possessed by government as well as the private sector," Holder said.