Criminals may have stolen more than half a million credit card numbers from merchant servers hosted by Networks Solutions, the Internet hosting company warned Friday.
In a letter sent to merchants who use its Ecommerce Hosting services, the company said that someone illegally installed software on company servers used handle credit card transactions initiated by 573,928 people between March 12 and June 8, 2009.
The code "may have been used to transfer data on certain transactions for approximately 4,343 of our more than 10,000 merchant Websites outside the company," Network Solutions said in the letter, signed by company chairman and CEO Roy Dunbar and sent to merchants on Friday.
Consumers who were possibly affected by the intrusion are also being notified by credit monitoring service TransUnion. They will get 12 months of free credit monitoring.
Customers of Network Solutions' other lines of business, such as its domain name registration or Web hosting services, were not affected by the incident, said Susan Wade, a company spokeswoman.
Law enforcement agencies are investigating, and so far the company has not heard of any credit card numbers being misused, following the incident.
The company has set up a Web site, where affected merchants and consumers can get more information on the breach.