> The infections were the result of legitimate developers writing apps using a counterfeit copy of Xcode, Apple’s iOS and OS X app development tool. The repackaged tool dubbed XcodeGhost surreptitiously inserted malicious code alongside normal app functions.

> XcodeGhost billed itself as faster to download in China, compared with Xcode available from Apple. For developers to have run the counterfeit version, they would have had to click through a warning delivered by Gatekeeper, the macOS security feature that requires apps to be digitally signed by a known developer.

Seems like a real world version of the Trusting Trust attack where the compiler is inserting malicious code.