One of the new features of iOS 16 is Lockdown Mode, which helps protect users from targeted cyber attacks by disabling several device features. With everything changing in lockdown mode, it also restricts web browsing – and now software engineer Alexis Laurs explains exactly how that happens.
Effect of lockdown mode on web browsing
Disabling Lockdown Mode in iOS 16 also disables WebAssembly. WASM is a powerful binary code format that enables high-performance apps on web pages. However, it can also be used to create a digital “fingerprint” of users, which helps third parties track people on websites and apps.
Interestingly, support for MP3 players on webpages is also disabled with lockdown mode. Lours believes that Apple wants to prevent attackers from using MP3 decoding for malicious purposes. Of course, this breaks any website with MP3 playback without a return to AAC or OGG formats.
The GamePad API, which was created to let users interact with game controllers on websites, does not work with Lockdown Mode enabled. This is because malicious websites can use details such as controller IDs to track users. Unsurprisingly, this breaks web games and platforms that rely on external game controllers.
Previewing files in web browser is also restricted with lockdown mode. For example, JPEG 2000 images and SVG fonts, which are specifically supported by Safari, are disabled, so websites cannot use these formats to target iOS users. PDF preview is also disabled for websites, as many PDF-related exploits have been found in the past.
Other disabled features include WebGL, the Speech Recognition API, and the Web Audio API.
What else does lockdown mode restrict?
In addition to restricting web browsing, the lockdown mode in iOS 16 also blocks most message attachments and link previews in Apple’s Messages app. Users with Lockdown Mode enabled only receive FaceTime calls from known numbers and iCloud Shared Albums are removed from the Photos app.
Apple also blocks configuration profiles and blocks access to devices over a wired connection with Lockdown Mode turned on.
Of course, Apple emphasizes that Lockdown Mode is intended for a specific group of users, who can be targeted by sophisticated spying threats. These users include journalists, activists and members of the government. This comes after the company last filed a lawsuit against ‘Pegasus’ spyware maker NSO Group.
Lockdown Mode is available as part of iOS 16, which is expected to be released this fall. Developers and users registered with the Apple Beta Software Program can now try out the iOS 16 beta.
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