Malware creators achieved the feat by targeting developers of legitimate iOS software. The infected apps were found to have been created via a tainted version of Xcode, a developer tool that can be downloaded for free from Apple's website.
"We’ve removed the apps from the App Store that we know have been created with this counterfeit software," Apple spokeswoman Christine Monaghan said in an email. "We are working with the developers to make sure they’re using the proper version of Xcode to rebuild their apps."Most of the infected apps targeted the Chinese market, WeChat was one of the few affected apps with a more international appeal, but the developer has already released a clean version of this popular messaging app.
Because Apple's download servers can be very slow in China, it's believed that the malware creators were able to trick Chinese developers into downloading the infected Xcode developer tool from a faster, China-based server.