Apple researcher Phil Schiller warned that introducing third-party app markets for iPhones in EU countries could create huge privacy and security concerns for users, even as Apple attempts to bolster security before regulatory rules take full effect.

The EU Digital Markets Act (DMA) forces Apple to open iPhones to third-party digital storefronts in EU member states. From March 2024, in the iOS 17.4 update, sideloading and alternative stores will be enabled in addition to Apple's own AppStore.

In preparation for the introduction of third-party stores, Apple has outlined changes to various charging methods, as well as security mechanisms to ensure user safety. However, Apple warns that this doesn't protect against every eventuality.

Phil Schiller, head of the App Store and Apple researcher, explained to FastCompany: "These new regulations bring new choices to developers, but they also bring new risks. This is an unavoidable problem. Therefore, we are doing everything we can to minimize these risks."

The introduction of third-party storefronts means there are new ways to install apps with malicious code on iPhones, which can cause many problems for end users. Apple's old "walled garden" approach and App Store review process would weed out these apps, with nearly 1.7 million submitted apps rejected in 2022 for not meeting privacy, security, and content standards.

Since the review process of third-party stores may not be as stringent as Apple's, Apple has introduced various elements to improve security, such as notarizing all apps before they are installed on the iPhone, regardless of which App Store they come from.

"We've made more than 600 new APIs available to developers, giving them the tools to build marketplaces, install apps, and let users control the process," Schiller said. "We've done a lot of core engineering and will continue to do that."

Users will also see an information sheet before installing the app, showing basic details about the app and adding more control over marketplace selection.

Still, Schiller added that Apple's protections have limitations and that it can't truly control the content of apps on alternative storefronts because notarization doesn't check the actual content, only whether the apps are safe and not malicious.

Apple researchers said: "The bottom line is that there are some things we don't allow on our App Store - things we deem unsafe or inappropriate. Whether other markets have the same terms and restrictions is not for us to decide."

Schiller noted: "While Apple has established rules after years of consultation with families and governments to prevent certain types of objectionable content from appearing in the App Store, these rules do not apply to other markets unless they choose to make their own rules and adopt whatever standards they propose. Will this increase the risk of users and families encountering objectionable content or other experiences? Yes, it will."