Apple iPhone up to X UBS checkm8 privileges management

Summaryinfo

A vulnerability classified as critical was found in Apple iPhone up to X. Affected is an unknown function of the component UBS Handler. Executing a manipulation can lead to privileges management. This vulnerability is tracked as CVE-2019-8900. The physical device can be targeted for the attack. Moreover, an exploit is present. This vulnerability is notable in history due to its background and the response it received. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Apple iPhone up to X (Smartphone Operating System). It has been declared as critical. This vulnerability affects an unknown function of the component UBS Handler. The manipulation with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

A vulnerability in the SecureROM of some Apple devices can be exploited by an unauthenticated local attacker to execute arbitrary code upon booting those devices. This vulnerability allows arbitrary code to be executed on the device. Exploiting the vulnerability requires physical access to the device: the device must be plugged in to a computer upon booting, and it must be put into Device Firmware Update (DFU) mode. The exploit is not persistent; rebooting the device overrides any changes to the device's software that were made during an exploited session on the device. Additionally, unless an attacker has access to the device's unlock PIN or fingerprint, an attacker cannot gain access to information protected by Apple's Secure Enclave or Touch ID features.

The weakness was disclosed 09/27/2019 by axi0mX as 1177542201670168576 as confirmed tweet (Twitter). The advisory is available at twitter.com. The vendor was not involved in the coordination of the public release. This vulnerability was named CVE-2019-8900. Local access is required to approach this attack. No form of authentication is required for a successful exploitation. Technical details are unknown but a public exploit is available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 07/29/2025). This vulnerability is assigned to T1068 by the MITRE ATT&CK project. This vulnerability has a historic impact due to its background and reception. The advisory points out:

EPIC JAILBREAK: Introducing checkm8 (read "checkmate"), a permanent unpatchable bootrom exploit for hundreds of millions of iOS devices. Most generations of iPhones and iPads are vulnerable: from iPhone 4S (A5 chip) to iPhone 8 and iPhone X (A11 chip).

A public exploit has been developed by axi0mX and been published immediately after the advisory. It is possible to download the exploit at github.com. It is declared as functional. As 0-day the estimated underground price was around $5k-$25k. The advisory illustrates:

What I am releasing today is not a full jailbreak with Cydia, just an exploit. Researchers and developers can use it to dump SecureROM, decrypt keybags with AES engine, and demote the device to enable JTAG. You still need additional hardware and software to use JTAG.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Smartphone Operating System

Vendor

• Apple

Name

• iPhone

Version

• 4S
• 5
• 5S
• 6
• 6S
• 7
• 8
• X

License

• commercial

Website

• Vendor: https://www.apple.com/

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