Checkm8 Exploit Opens Door to Unpatchable Jailbreak on iPhone 4S Through iPhone X

A security researcher who goes by "axi0mX" on Twitter today released "checkm8," which he claims is a bootrom exploit for iOS devices equipped with A5 through A11 chips, including the iPhone 4S through iPhone X, several iPad models dating back to the iPad 2, and the fifth-generation iPod touch and later.

trio iphones ios
This would be the first publicly released bootrom exploit since the iPhone 4 in 2010 and pave the way for a permanent, non-patchable jailbreak on hundreds of millions of affected iOS devices. Since the bootrom is read-only, Apple cannot patch this type of exploit with a software update.


The bootrom exploit has many other possibilities on affected devices, including downgrading iOS versions without SHSH blobs or APTickets, dual booting iOS, and running custom firmwares, according to jailbreak enthusiasts.

This is significant news in the jailbreaking community, as the last bootrom exploit known as "limera1n" was released by George "geohot" Hotz nearly a decade ago for devices with A4 chips and earlier, including the iPhone 4, iPhone 3GS, the third- and fourth-generation iPod touch, and the original iPad.

Popular Stories

Generic iOS 18 Feature Real Mock

iOS 18 Available Now With These 8 New Features For Your iPhone

Sunday September 15, 2024 10:09 am PDT by
Following over three months of beta testing, iOS 18 was finally widely released to the public on Monday, September 16. The update is available in the Settings app under General → Software Update on the iPhone XS and newer. Below, we have highlighted eight key new features included in iOS 18, and Apple shared a complete list of new features and changes last week. Note that Apple...
iOS 18 Public Beta Thumb 1

Here's When iOS 18 Rolls Out Today in Every Time Zone

Monday September 16, 2024 3:56 am PDT by
It's that time of year again. Apple is about to release iOS 18, which promises to bring a range of new features and improvements to iPhones worldwide. It's Apple's biggest software update of the year, and the company is expected to release it sometime today – Monday, September 16. Based on past releases, the update is likely to drop at around 10:00 a.m. Pacific Time/1:00 p.m. Eastern...
apple silicon mac lineup wwdc 2022 feature purple

M4 Macs, New iPad Mini, and iPad 11 Expected at Upcoming Apple Event

Sunday September 15, 2024 5:29 am PDT by
Apple will likely hold another event in October this year to announce new Macs and iPads. If so, it would be the fourth time in the last five years that Apple has held an event in October. Last year, Apple held a virtual event on Monday, October 30 to announce new MacBook Pro and iMac models with the M3 series of chips. In his Power On newsletter today, Bloomberg's Mark Gurman reiterated...
M4 Mac mini Black Ortho Cooler

Apple Leaks New Mac Mini With 5 USB-C Ports

Monday September 16, 2024 11:40 am PDT by
Apple has seemingly leaked the rumored next-generation Mac mini with five USB-C ports, according to a code change within Apple software that was discovered today by MacRumors contributor Aaron Perris. The code refers to an unreleased Mac mini model with an Apple silicon chip and five ports, which lines up with a previous report from Bloomberg's Mark Gurman that said the next Mac mini will be ...
16 pro

iPhone 16 Pro Demand Has Been Lower Than Expected, Analyst Says

Sunday September 15, 2024 3:58 pm PDT by
Apple analyst Ming-Chi Kuo today said demand for the iPhone 16 Pro and iPhone 16 Pro Max has been "lower than expected" since the devices became available to pre-order in the U.S. and dozens of other countries on Friday. Kuo said his data is based on a "supply chain survey" and shipping estimates listed on Apple's online store. Kuo estimated that sales of all four iPhone 16 models reached...
Beyond iPhone 13 Better Blue Face ID Single Camera Hole

10 Reasons to Wait for Next Year's iPhone 17

Friday September 13, 2024 2:40 am PDT by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models simultaneously, which is why we sometimes get rumored feature leaks so far ahead of launch. The iPhone 17 series is no different – already we have some idea of what to expect from Apple's 2025 smartphone lineup. If you plan to skip...

Top Rated Comments

zorinlynx Avatar
65 months ago

This can't be good for the security of these devices...

And have malware installed or spying on you. No thanks. Apple should have gotten their sh** together and not have had the exploit open for nearly a week.
This is a bootrom exploit. It can only be exploited when the device is in DFU recovery mode and will not affect the security of devices being used normally.

This is really the best kind of jailbreak exploit because only the people who really want to go out of their way to jailbreak can use it. Regular users are safe; all it means is that people can do whatever they like with these devices they own now.
Score: 35 Votes (Like | Disagree)
itsmilo Avatar
65 months ago

All the cool kids violate their warranty. Didn't you know?
one restore on iTunes and your warranty is „restored“ so to speak
Score: 28 Votes (Like | Disagree)
tobefirst ⚽️ Avatar
65 months ago
I haaaaaaate the new force press/haptic touch menu on iOS 13. I would consider jail breaking just to go back to how that worked on my X on iOS 12.
Score: 16 Votes (Like | Disagree)
Jeremy1026 Avatar
65 months ago
I haven't been jailbroken since the 3G, what's the big draw of a jailbreak now a days?
Score: 15 Votes (Like | Disagree)
redheeler Avatar
65 months ago
Good, now we can have proper downgrade rights on these devices. It's sad that something like this is needed to, for example, downgrade to iOS 10 on an iPad Air 2 for the simple purpose of running 32-bit apps.
Score: 14 Votes (Like | Disagree)
Krevnik Avatar
65 months ago

Once the data is copied off the phone can't you brute force it without fear of being locked out? What's the encryption like?
You can read through the details yourself if you want: https://www.apple.com/business/docs/site/iOS_Security_Guide.pdf

The NAND itself is encrypted with AES 256. The passcode is the weak point, but to generate the AES 256 key from the passcode, you need the passcode and the unique AES 256 key burned into the Secure Enclave on the SOC. The passcode is run through PBKDF2 and then tangled with the AES 256 key in a one-way operation.

So dumping the flash raw means you face AES 256 at full strength, even if you know the passcode, because you also need the AES 256 key from the SOC to be able to recreate the key yourself if you aren't just brute forcing AES.

The fastest way to crack an iPhone is to brute force the passcode and bypass the lockout on attempts if you can. It also gives you the most access to the content.

Individual containers/files can be encrypted with separate keys based on the level of access the OS should have in different states of lock/unlock, on top of the NAND encryption. So if you dump the flash unencrypted, you then also need to crack the containers for things like email and messages which are also AES 256 encryption. All the more reason to focus even more on the passcode and attempt lockout mechanisms.


This is a bootROM exploit. Every iPhone ever manufactured excluding the iPhone XS and 11 series will always be vulnerable to this exploit regardless of any iOS updates. There is no patch.
Apple still manufactures the iPhone 8 and 3rd Gen Air. I wouldn't be surprised if we see manufacturing runs of those that include the patched boot ROM.
Score: 14 Votes (Like | Disagree)