Progressive officials Thursday confirmed that the company sent out letters in January to 13 people informing them that confidential information, including names, Social Security numbers, birth dates and property addresses had been wrongfully accessed by an employee who has since been fired.

Michael O'Connor, a spokesman for the Mayfield Village, Ohio-based company, said officials were alerted to the situation when a local woman complained about receiving calls from a Progressive agent inquiring about her house being under foreclosure.

"What happened was that the former employee, who purchased foreclosure property, wrongly used the information in a real estate database," O'Connor said. Though there was no actual hacking involved to get at the data, her actions constituted a violation of Progressive's code of ethics, O'Connor said.

"We investigated the situation, the employee was terminated, and we alerted the people whose data was accessed," he said, adding that the matter was resolved in January.

Such incidents underscore the threat posed to corporate data by malicious insiders and by workers who accidentally leak sensitive information, said Phil Neray, a vice president at Guardium Inc., a Waltham, Mass.-based vendor of database security products. "Most companies have done a good job with perimeter security" and are now finding out they need similar controls internally, Neray said.