Apple has removed hundreds of legitimate apps on its App Store which had been infected by malware dubbed XCodeGhost. If you still have them installed, it’s a good idea to stop using them for now.
What appears to have happened is that Chinese developers were unknowingly downloading unoffical hacked copies of XCode, the program used to develop apps for all Apple devices. When developers built their apps and posted them to the App Store, the modified XCode would install malicious code in the app. Without knowledge to the user (or the developers), when the app is then run on a user's device, it would send private information to the servers run by the hackers.
The good news is the apps are down but please verify the list located here. The lesson for developers is obvious: Allow Use Official Download Links. You can read more details at MacRumors. [MacRumors]