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.

Lightning iPhone 7
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.

apple lightning usb camera adapter
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.

Related Forums: iOS 11, iOS 12

Top Rated Comments

christarp Avatar
39 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)
Turnpike Avatar
39 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)
Scooz Avatar
39 months ago
Apple seemingly doing anything to sell their overpriced adapters...
Score: 7 Votes (Like | Disagree)
MacRS4 Avatar
39 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)
alphaod Avatar
39 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)
robertcoogan Avatar
39 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

16 inch macbook pro m2 render

When Can We Expect the Redesigned MacBook Pros Now?

Wednesday June 16, 2021 7:11 am PDT by
With no sign of redesigned MacBook Pro models at this year's WWDC, when can customers expect the much-anticipated new models to launch? A number of reports, including investor notes from Morgan Stanley and Wedbush analysts, claimed that new MacBook Pro models would be coming during this year's WWDC. This did not happen, much to the disappointment of MacBook Pro fans, who have been...
YouTube Picture in Picture Feature

YouTube Says iOS Picture-in-Picture Coming to All US Users

Friday June 18, 2021 9:41 am PDT by
After a long wait, YouTube for iOS is officially gaining picture-in-picture support, allowing all users, non-premium and premium subscribers, to close the YouTube app and continue watching their video in a small pop-up window. In a statement to MacRumors, YouTube says that picture-in-picture is currently rolling out to all premium subscribers on iOS and that a larger rollout to all US iOS...
2021 back t0 school

Apple Launches 2021 Back to School Promotion: Free AirPods With Eligible Mac or iPad Purchase

Thursday June 17, 2021 4:56 am PDT by
Apple today launched its seasonal back-to-school sale for the upcoming school year in the United States and Canada, offering students free AirPods alongside purchases of select Macs and iPad models. Similar to last year's promotion, this year's offer includes free AirPods alongside the purchase of a MacBook Air, MacBook Pro, the new 24-inch iMac, the Mac Pro, Mac mini, and the new M1-powered ...
applecare lower prices

Apple Lowers Prices of AppleCare+ Plans for M1 MacBook Air and MacBook Pro

Thursday June 17, 2021 7:33 am PDT by
Apple today lowered the prices of AppleCare+ plans for MacBook Air and 13-inch MacBook Pro models equipped with the M1 chip. Coverage offered by the plans, as well as accidental damage fees, appear to remain unchanged. In the United States, AppleCare+ for the MacBook Air now costs $199, down from $249. The new price applies to both M1 and Intel-based MacBook Air models, although Apple no...
maxresdefault

Video: 20 Annoyances Apple Fixed in iOS 15 and macOS Monterey

Friday June 18, 2021 11:36 am PDT by
With iOS 15 and macOS Monterey, Apple is adding several quality of life improvements, which are designed to address some of the complaints that people have had with these operating systems for years now. Subscribe to the MacRumors YouTube channel for more videos. In our latest YouTube video, we're highlighting some of our favorite "fix" features that address long-running problems in iOS and...
Top Stories 63 Feature

Top Stories: Beats Studio Buds Announced, Apple Watch Series 7 Rumors, and More

Saturday June 19, 2021 6:00 am PDT by
The Apple news cycle started to move beyond WWDC this week, but that doesn't mean there still wasn't a lot to talk about, led by the official debut of the much-leaked Beats Studio Buds that might give us a hint of what to expect for the second-generation AirPods Pro. With no hardware announcements at WWDC, we also took a look at when we might finally see the long-rumored redesigned MacBook...
m1 v intel thumb

Intel Processor Market Share May Fall to New Low Next Year Due to Apple Silicon

Friday June 18, 2021 2:06 am PDT by
Intel may see its market share fall to a new low next year, in large part thanks to Apple's decision to move away from using Intel processors in its Mac computers and instead use Apple silicon. Apple announced last year that it would embark on a two-year-long journey to transition all of its Mac computers, both desktops, and laptops, to use its own in-house processors. Apple is expected to...
space gray magic accessories trio

Apple Stops Selling Magic Accessories in Space Gray

Friday June 18, 2021 9:16 am PDT by
Apple this week stopped selling its Magic Keyboard with Numeric Keypad, Magic Mouse 2, and Magic Trackpad 2 accessories for the Mac in a Space Gray color, around three months after discontinuing the iMac Pro, which also came in Space Gray. Last month, Apple listed the Space Gray accessories as available while supplies last, and the company has now removed the product pages from its website...
maxresdefault

Apple CEO Tim Cook: Sideloading Apps Would 'Destroy the Security' of the iPhone

Wednesday June 16, 2021 10:49 am PDT by
Apple CEO Tim Cook this morning participated in a virtual interview at the VivaTech conference, which is described as Europe's biggest startup and tech event. Cook was interviewed by Guillaume Lacroix, CEO and founder of Brut, a media company that creates short-form video content. Much of the discussion centered on privacy, as it often does in interviews that Cook participates in. He...
3nm apple silicon feature

Apple Supplier TSMC Readies 3nm Chip Production for Second Half of 2022

Friday June 18, 2021 6:59 am PDT by
Apple supplier TSMC is preparing to produce 3nm chips in the second half of 2022, and in the coming months, the supplier will begin production of 4nm chips, according to a new report from DigiTimes. Apple had previously booked the initial capacity of TSMC's 4nm chip production for future Macs and more recently ordered TSMC to begin production of the A15 chip for the upcoming iPhone 13,...