Target's head of technology handed in her resignation today, months after the company suffered one of the largest data breaches in retail history. Beth Jacob, who has served as Target's chief information officer and executive vice president of technology services since 2008, is vacating both positions and departing the company immediately. According to CEO Gregg Steinhafel, the retailer has already launched a search for an interim CIO to help steer Target through a major security overhaul. "While we are still in the process of an ongoing investigation, we recognize that the information security environment is evolving rapidly," Steinhafel said.

The sophisticated attack was launched during the popular Black Friday shopping weekend and stretched on for three weeks. Hackers made their way into Target's computer systems by using stolen credentials from a refrigeration contractor. By the time the company became wise to the breach, perpetrators had already stolen data on 40 million credit and debit card accounts. Target later revealed that other information (addresses, phone numbers, etc.) on up to 70 million shoppers was also compromised. A federal investigation remains ongoing. In her resignation letter — which does not mention the disastrous incident — Jacob says choosing to leave Target was a "difficult decision." Last week, Target reported $61 million in costs related to the breach, though the bulk of that damage was covered by the retailer's insurance.