Apple has done a major sweep of its App Store and banned 256 apps, according to NBC News. Software contained within these apps were found to be secretly collecting personal information without users' consent, and it all traces back to the advertising firm Youmi in China.

Youmi provided the makers of these apps software that collected information like email addresses and smartphone serial numbers, according to the Verge.

It's estimated that there were 1 million downloads of these information-stealing apps, according to TechCrunch.

However, as horrifying as this news may be, it's also believed that many app makers weren't aware of this malicious software to begin with, according to NBC News. The data was uploaded exclusively to Youmi's own databases.

Apple wasn't taking any chances, though, and banned the apps as soon as they received the information.

"The apps using Youmi's SDK have been removed from the App Store and any new apps submitted to the App Store using this SDK will be rejected. We are working closely with developers to help them get updated versions of their apps that are safe for customers and in compliance with our guidelines back in the App Store quickly," said Apple via statement, according to Tech Crunch.