Network Solutions, one of the biggest domain registrars and web hosting companies in the world, announced a data breach incident yesterday after malicious code had been found on its e-commerce servers. According to the company, the malware might have intercepted transactions from 4,343 websites, compromising 573,928 credit cards in the process.

The unauthorized code was detected by Network Solutions technicians during routine check-ups of its e-commerce infrastructure. The company sells web hosting solutions particularly fitted for merchants, which run on servers housed on a separate network segment.

However, only a portion of these servers, which host a total of over 10,000 e-commerce websites, have been compromised. According to the company, details about credit card transactions that took place between March 12 and June 8 on 4,343 websites might have been intercepted and forwarded to an outside location.

Unnamed law enforcement agencies have been notified and are currently investigating the incident. Meanwhile, the company is in the process of notifying the affected merchants who, in turn, will have to notify the customers whose credit cards might have been compromised.

"At this point, we have no reports or other reasons to believe that any credit card account information has been misused and, under established practice, credit card issuing companies generally will not hold our merchants’ customers liable for any fraudulent purchases made using their credit card account numbers that are reported in a timely way to the issuer," a statement from the company reads.

Network Solutions has contracted TransUnion to handle notification of the affected U.S. cardholders on behalf of its merchants. In order to benefit from this service, the owners of the affected websites need to go at careandprotect.com, log in with their Network Solutions username and password and opt-in.

Details about how the unauthorized code was installed or where it was sending the stolen data have not yet been released, because of the ongoing investigation. "We are deeply sorry for any concern or inconvenience this may cause our merchants or their customers," the company noted.