The theft of credit card and personal identity information is big business. We’ve all seen the headlines about data breaches at Target, Home Depot, and JPMorgan Chase. At JPMorgan Chase, personal information for 83 million households and small businesses was stolen, including names, addresses, phone numbers, and emails. The theft of this personal information is not only expensive to JPMorgan Chase (and its insurers), and not only upsetting for all the people impacted—it can also lead to more cyber attacks in the future, since personal information helps cybercriminals better target individuals. To investigate a cyber attack, you need to be able to look back in time and figure out what happened: how did the attackers get in the door? Where did they go, and what did they take once they got inside?