Apple:

We always recommend developers use the free, secure tools we provide them — including Xcode — to ensure they’re creating the most secure apps for App Store customers. Some developers downloaded counterfeit versions of Xcode that have been infected with malware and created apps that were just as infected.

Apple incorporates technologies like Gatekeeper expressly to prevent non-App Store and/or unsigned versions of programs, including Xcode, from being installed. Those protections had to have been deliberately disabled by the developer for something like XcodeGhost to successfully install.

And:

We have removed the apps from the App Store that we know have been created with this counterfeit software and are blocking submissions of new apps that contain this malware from entering the App Store.

We’re working closely with developers to get impacted apps back on the App Store as quickly as possible for customers to enjoy.

A list of the top 25 most popular apps impacted are listed below. After the top 25 impacted apps, the number of impacted users drops significantly.

If you are an iOS developer, anywhere in the world, be sure to verify your copy of Xcode. Here’s how.