The CIO of Target, one of the world's largest retail chains, has become the first casualty of the massive data breach that occurred in the company's systems last year.

Beth Jacob, who was the executive in charge of Target's computer systems, is leaving as the firm attempts to overhaul its network security and computer infrastructure. She was named CIO in 2008 and played a major role in the firm's e-commerce operations.

In the wake of the data breach, the second largest in US history, critics have panned the company's system security, accusing it of failing to take basic steps to avoid an infiltration by hackers.

Revamp

The source of the breach, which lifted the details of more than 40 million people, was just one email. An unprotected supplier for Target - a refrigeration company - was infected and then passed the malware on to the retail giant's systems.

Part of the revamp to the company's systems involves changing the structure of the business itself to closely link technology and compliance areas, a step taken by big banks in recent years.

Target's incoming CIO, whoever they might be, will be called on to immediately oversee a payment system upgrade, which the company is spending more than $100 million (£60 million, AU$110 million) on.