Apple said Tuesday that it removed a seller from its online applications store after discovering that he gamed the store's sales ranking system to make it appear as though his e-books accounted for 42 of the site's top 50 electronics books.
Apple said the hack was carried about by a developer named Thuat Nguyen.
"His apps were removed from the App Store for violating the developer Program License Agreement, including fraudulent purchase patterns," Apple said in a statement.
The company did not provide details about how Nguyen managed to rig its sales data. Some observers are speculating that he merely manipulated sales figures, while others believe Nguyen may have actually gained access to App Store user accounts to make unauthorized purchases.
Nguyen listed his Web site as "mycompany", an Internet address that reportedly leads to a domain name parking page.
Apple insisted App Store or iTunes users' information is not at risk as a result of the incident. "Developers do not receive any iTunes confidential customer data when an app is downloaded," the company said.
Still, Apple cautioned its customers to be vigilant for suspicious transactions.
"If your credit card or iTunes password is stolen and used on iTunes we recommend that you contact your financial institution and inquire about cancelling the card and issuing a chargeback for any unauthorized transactions," Apple said.
"We also recommend that you change your iTunes account password immediately," Apple added. Investors shrugged off news about the breach. Apple shares were up .69%, to $248.65, in midday trading Tuesday.