Security Researchers Find Way to Prevent USB Restricted Mode From Activating on iOS Devices

Security researchers claim to have discovered a loophole that prevents an iPhone or iPad from activating USB Restricted Mode, Apple's latest anti-hacking feature in iOS 12 beta and iOS 11.4.1, which was released on Monday.

USB Restricted Mode is designed to make iPhones and iPads immune to certain hacking techniques that use a USB connection to download data through the Lightning connector to crack the passcode.


iOS 11.4.1 and iOS 12 prevent this by default by disabling data access to the Lightning port if it's been more than an hour since the iOS device was last unlocked. Users can also quickly disable the USB connection manually by engaging Emergency SOS mode.

However, researchers at cybersecurity firm ElcomSoft claim to have discovered a loophole that resets the one-hour counter. The bypass technique involves connecting a USB accessory into the Lightning port of the iOS device, which prevents USB Restricted Mode from locking after one hour.

ElcomSoft's Oleg Afonin explained the technique in a blog post:

What we discovered is that iOS will reset the USB Restrictive Mode countdown timer even if one connects the iPhone to an untrusted USB accessory, one that has never been paired to the iPhone before (well, in fact the accessories do not require pairing at all). In other words, once the police officer seizes an iPhone, he or she would need to immediately connect that iPhone to a compatible USB accessory to prevent USB Restricted Mode lock after one hour. Importantly, this only helps if the iPhone has still not entered USB Restricted Mode.

According to Afonin, Apple's own $39 Lightning to USB 3 Camera Adapter can be used to reset the counter. Researchers are currently testing a mix of official and third-party adapters to see what else works with the bypass technique.


Afonin notes that ElcomSoft found no obvious way to break USB Restricted Mode once it has been engaged, suggesting the vulnerability is, in his words, "probably nothing more than an oversight" on Apple's part. Still, at present its existence provides a potential avenue for law enforcement or other potentially malicious actors to prevent USB Restricted Mode from activating shortly after seizure.

Both iOS 11.4.1 and iOS 12 beta 2 are said to exhibit the same behavior when exploiting the loophole. However, expect this to change in subsequent versions of iOS – Apple continually works on strengthening security protections and addressing iPhone vulnerabilities as quickly as possible to defend against hackers.

Apple reportedly introduced USB restrictions to disable commercial passcode cracking tools like GrayKey. Afonin cites rumors that the newer GrayShift tool is able to defeat the protection provided by USB Restricted Mode, but the research community has yet to see firm evidence confirming this.

Top Rated Comments

(View all)
Avatar
23 months ago
Interesting, so the cops would need to confiscate the alleged evidence and transport it back to wherever they take it and then keep it plugged into the device. might be tough to do within an hour, but I'm sure they'll find a way. And I'm also sure Apple will find a way to close this loophole. Cat and mouse continues.
Score: 10 Votes (Like | Disagree)
Avatar
23 months ago
There is always going to be a ping-pong, back-and-forth effect to this kind of thing with problems and solutions; but having an Apple device and having Apple on your side working to protect it is, while not perfect, the closest thing to it you will find with any company. Nobody else really cares about protecting your data quite like Apple does.
Score: 8 Votes (Like | Disagree)
Avatar
23 months ago
Apple seemingly doing anything to sell their overpriced adapters...
Score: 7 Votes (Like | Disagree)
Avatar
23 months ago
Have I misunderstood this? What they're saying is that <1 hour and you plug in a USB, it resets the count-down timer for the USB lockout.

So imagine you unlock/lock your phone, and plug it in to your computer shortly afterward. You wouldn't want the USB lock to engage would you? Say for example if you were copying 100GB of movies to it.

Or is the lack of 'trusted' devices enabling the reset of the counter? I.e. A mistake on the expected behaviour.

PS. I've not had nearly enough coffee yet.
Score: 7 Votes (Like | Disagree)
Avatar
23 months ago
Makes sense seeing some accessories like the HDMI adapter do not require authorization in the first place.

I wouldn't see this as an oversight. Can't have a perfect solution.
Score: 6 Votes (Like | Disagree)
Avatar
23 months ago
One could also change the 6-digit PIN to a password (mix of characters) and defeat any graybox regardless.
Score: 6 Votes (Like | Disagree)

Top Stories

Apple Acquires Weather App Dark Sky

Tuesday March 31, 2020 10:22 am PDT by Juli Clover
Apple has acquired weather app Dark Sky, Dark Sky's developers announced today. Dark Sky is one of the most popular weather apps on the App Store, known for its accuracy and storm warnings. Our goal has always been to provide the world with the best weather information possible, to help as many people as we can stay dry and safe, and to do so in a way that respects your privacy. There is no ...

Zoom Accused of Misleading Users With 'End-to-End Encryption' Claims Amid Other Security Issues [Updated]

Wednesday April 1, 2020 2:47 am PDT by Tim Hardwick
Zoom is facing fresh scrutiny today following a report that the videoconferencing app's encryption claims are misleading. Zoom states on its website and in its security white paper that the app supports end-to-end encryption, a term that refers to a way of protecting user content so that the company has no access to it whatsoever. However, an investigation by The Intercept reveals that...

Case for Upcoming Low-Cost iPhone Shows Up at Best Buy With Alleged April 5 Stock Date

Monday March 30, 2020 4:25 pm PDT by Juli Clover
Apple has a new low-cost iPhone in the works, which is supposed to be launching sometime in the first half of 2020. Given the ongoing situation in the United States and other countries, it's been unclear if the device is going to launch within the planned timeline, but there are signs that it could be coming soon. We started seeing cases for the new low-cost iPhone back in early February,...

Bloomberg: Apple's 5G iPhone Still on Schedule for Fall Launch, But Future Products Could Be Delayed

Monday March 30, 2020 2:40 am PDT by Tim Hardwick
Apple's 5G iPhone is still on track to launch within the company's typical annual fall release schedule, according to a new Bloomberg report on filed on Monday. Signs are that Apple's Chinese-centric manufacturing -- of which Hon Hai is the linchpin -- is slowly getting back on track. The next iPhones with 5G wireless capabilities remain on schedule to launch in the fall, partly because mass...

Testing Brydge's New Pro+ Keyboard With Trackpad for iPad Pro

Monday March 30, 2020 2:04 pm PDT by Juli Clover
Well ahead of when Apple introduced trackpad support in iOS 13.4, Brydge announced an iPad Pro keyboard with a built-in multi-touch trackpad. We have one of Brydge's new Pro+ keyboards on hand, and thought we'd check it out to see how it works with Apple's new 2020 iPad Pro models. Subscribe to the MacRumors YouTube channel for more videos. The Brydge Pro+ keyboard is similar in design to...

Apple's Work on New Upcoming Products Progressing Normally as Employees Adjust to Telecommuting

Monday March 30, 2020 11:58 am PDT by Juli Clover
Apple's development of upcoming products is progressing as usual despite the fact that Apple employees around the world are working from home, according to a new report today out from Bloomberg. Apple is still working on new versions of the HomePod, Apple TV, MacBook Pro, budget iPads, Apple Watch, iPhone, and iMac, all of which could be released "as early as later this year" and have been...

Apple Releases ProRes RAW Beta for Windows

Monday March 30, 2020 9:33 am PDT by Juli Clover
Apple today released ProRes RAW for Windows in a beta capacity (via Mark Gurman), with the software designed to allow ProRes RAW and ProRes RAW HQ video files to be watched in compatible applications on Windows machines. According to Apple, the software will let the files be played within several Adobe apps: Adobe After Effects (Beta) Adobe Media Encocder (Beta) Adobe Premiere...

Apple Configurator 2 Updated With New Features, Including Support for Restoring Firmware on 2019 Mac Pro

Tuesday March 31, 2020 5:34 am PDT by Joe Rossignol
Apple Configurator 2 has been updated to version 2.12 with several improvements, including support for restoring firmware on the 2019 Mac Pro. The release notes:• Added support for restoring firmware on the 2019 Mac Pro • Allow access to websites using TLS 1.0 and 1.1 • VPN: Configure Provider Designated Requirement for Custom SSL connection type • VPN: Configure network options for ...

Seemingly Unreleased Version of Logic Pro X With Live Loops Appears on Apple's Education Site [Updated]

Sunday March 29, 2020 7:23 am PDT by Hartley Charlton
Update: Apple has replaced the Logic Pro X image with an older version. Original story follows. A seemingly unreleased version of Logic Pro X has appeared on Apple's education site, as spotted by a Reddit user. The image from Apple's education products page shows a 16-inch MacBook Pro running Logic Pro X, but with a familiar interface that looks extremely similar to GarageBand's Live Loops ...

Apple's 2020 MacBook Air vs. 2020 iPad Pro

Wednesday April 1, 2020 2:45 pm PDT by Juli Clover
Apple in March updated both the MacBook Air and the iPad Pro, and with the iPad Pro increasingly positioned as a computer replacement, we thought we'd compare both new machines to see how they measure up and which one might be a better buy depending on user needs. Subscribe to the MacRumors YouTube channel for more videos. We're comparing the base model 12.9-inch iPad Pro and the base model...