Checkm8 Implications on iOS DFIR, TFP0, #FreeTheSandbox, Apple, and Google

By ZecOps Research Team
| November 4, 2019

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Thanks to Checkm8 – a bootrom vulnerability that exist on most iPhones/iPads (<A12), a generic method to bypass the iOS sandbox restrictions will be made public within days/weeks for all previous and future versions of iOS! An upcoming release of a generic capability to extract the filesystem of a suspected iOS devices will help to boost digital forensics investigations.

Which devices are vulnerable: almost every iPhone/iPad until iPhone X.
Which devices are not vulnerable? iPhone Xs/Xr and 11/11Pro.

Notably, the release of checkm8 will help to enhance Digital Forensics and Incident Response (DFIR) on iPhone X (and all previous models) and make it easier to perform deep investigations compared to the newer models such as iPhone Xs / Xr / 11. Whilst iPhones running on A12+ chipsets benefit from a Pointer Authentication Code (PAC) security mitigation, which makes exploitation significantly harder, the inspectability of such devices remain to be a major challenge and is crucial for successful DFIR investigations when initial suspicion is raised.

Furthermore, this vulnerability, amongst other capabilities, allows iPhone owners to modify boot arguments which, for example, can enable users to have an even safer iOS version than vanilla iOS.

When ZecOps started the #FreeTheSandbox initiative, we did not foresee a release of a bootrom exploit covering the latest production devices. Thanks to @axi0mX bootrom exploits have become a reality and changed the game. A number of experienced and reputable researchers (such as @qwertyoruiopz, @siguza and many other fine individuals) worked tirelessly to make use of checkm8 in order to set the iOS sandbox free (a.k.a Checkra1n).

Soon it will be released publicly.

Implications to Apple & Google:

Since almost every iOS device is now susceptible to jailbreaking without requiring new exploit chains or bypassing mitigation techniques, it is time for Apple to rethink its sandboxing strategy and allow iOS users to freely inspect their devices including A12 and A13 devices without the need of a Local Privilege Escalation (LPE) exploit.

Device vendors, such as Apple and Google, will soon realize that Checkm8-style unpatchable vulnerabilities are inevitable. Restricting sandbox policy against device owners does not make sense and only benefit attackers that oftentimes leverage the sandbox to avoid detection.

Notable case was Google Project Zero discovery of 14 vulnerabilities leveraged in-the-wild against any iOS visitors of certain websites whilst attackers didn’t even try to hide and executed their payloads from a tmp folder. Following Checkm8, many researchers will take a closer look at bootrom vulnerabilities. Since boot level vulnerabilities are unavoidable, and we would like to encourage Google & Apple to open-up Android/iOS for inspectability with the consent of end-users. This will enable to perform complete DFIR investigations without flashing a new image, slowing down time-critical investigations or tampering with attacks’ evidence.

Should device-vendors decide to consider this, ZecOps will collaborate with each vendor to enumerate key things that would be important to enable mobile DFIR investigations. Furthermore, enabling users to inspect their devices does not increase device issues, on the contrary, organizations that permit CYOD policy would prefer devices that are inspectible, especially in the Defense / Government sectors.

Update to ZecOps Task-For-Pwn-0 Project

Following this release, ZecOps decided that we should focus more on bootrom vulnerabilities for both iOS and Android.

iOS Bootrom vulnerabilities for A12/A13: We’re willing to offer up to $250,000 bounties for A12 and A13 bootrom vulnerabilities.
Android support: With this blog post, we are happy to announce that we are opening up our program for Android devices too. As a starting point, we’ll only examine Android boot-level bugs.
Existing LPEs on iOS 13+: Until we receive bootrom submissions, on iOS we’ll focus exclusively on LPEs for A12/A13 devices.

Other TFP0 Term & Updates

Disclosures / (non)-exclusivity / and other terms will be discussed with researchers at the time of the submission. Price for the bounty will be determined following an agreement on the terms.

Submissions

Send submissions to [email protected]. The public key is available at the bottom of this post.

It has been almost two months since we launched the program and so far it has been a great success, since it helps our DFIR investigations globally! More updates to this program will be provided soon, as it is continuously evolving.

We would like to thank everyone who supports #FreeTheSandbox initiative and hope that soon we will all be allowed to inspect devices we purchased without the need to break into them.

If you wish to analyze suspected devices – please contact us here [email protected]

The ZecOps TFP0 Team

Bonus

If you read all the way till here – here’s a bonus:
To receive #FreeTheSandbox stickers delivered to you, fill this form

[email protected] public key below:

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