Apple pulls apps for spying on users

Apple has pulled 256 apps from its store after discovering that they were gathering information on users.

The apps, mostly developed in China, all used a software development kit (SDK) called Youmi to allow advertising to be built in.

However, unknown to the developers producing the apps, the SDK also contained some secret code. This meant that the apps captured data on their users, such as their email address and device identifier, and automatically sent it to Youmi.

Apple's rules on apps ban them from sharing user data without getting the users' permission. It vets all apps before listing them in its store, and has a reputation for maintaining quality as well as security.

"The apps using Youmi's SDK will be removed from the App Store and any new apps submitted to the App Store using this SDK will be rejected," the company says in a statement.

"We are working closely with developers to help them get updated versions of their apps that are safe for customers and in compliance with our guidelines back in the App Store quickly."

The problem was discovered by mobile analytics firm SourceDNA, which says it's the first time its seen apps getting round the Apple review process. But, it says, it may not be the last.

"Given how simple this obfuscation is and how long the apps have been available that have it, we're concerned other published apps may be using different but related approaches to hide their malicious behaviour," it says in a statement.

"We're continuing to add new features to our engine to discover anomalous behaviour in app code and find out if this is the case."

Only last month, in fact, Apple pulled dozens of Chinese language apps after discovering that they'd been infected with malicious software called XCodeGhost - despite having made it through the review process.

Youmi has apologised to app developers and promised to put things right.

"Youmi is actively communicating with Apple and hope to be able to solve the matter asap," it says in a statement. "After things have been properly resolved, we will give reasonable compensation. Once again, we express deep regret to affected developers."

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