The iOS App Store is usually a trustworthy source of software. But as hackers tend to do, they found a way to get their nefarious wares into the China version of the software supermarket. By using altered versions of Apple' development tool Xcode they were able to slip malware into apps being built by unaware devs. The problem started when developers downloaded altered versions of Xcode (named "XcodeGhost" Alibab researchers) from third-party sites. When apps built with the modified compiler are launched, they collect the phone's name, UUID, language and country, current time and network type. That data is then encrypted and sent to servers. Not a huge breach, but no one wants to be tracked by unknown sources.