PKfail vulnerability in Secure Boot turns out to be more common than expected

A large-scale vulnerability in the Secure Boot security system, dubbed PKfail, turned out to be much more widespread than previously thought. The problem, called PKfail, affects ATMs, payment terminals, medical devices, gaming consoles, corporate servers and even voting machines. The use of test platform keys in production systems for over 10 years has compromised the security of devices from leading industry manufacturers.

Image source: geralt/Pixabay

Binarly researchers found that the number of device models using compromised platform test keys increased from 513 to 972. Affected manufacturers include Acer, Dell, Gigabyte, Intel, Supermicro, Aopen, Fornelife, Fujitsu, HP and Lenovo. Keys marked “DO NOT TRUST” in certificates were never intended for use in industrial systems, but have ended up embedded in hundreds of device models.

Platform keys form a cryptographic root-of-trust anchor between hardware and firmware. They are the foundation for Secure Boot, an industry standard that provides cryptographic security in a device’s pre-boot environment. Integrated into UEFI (Unified Extensible Firmware Interface), Secure Boot uses public key cryptography to block the boot of any code that is not signed with a pre-approved digital signature. Compromising these keys undermines the entire security chain established by Secure Boot.

The situation worsened after the publication of the private part of one of the test keys on GitHub in 2022. This opened up the possibility of carrying out complex attacks involving the introduction of rootkits into UEFI devices protected by Secure Boot. The number of models using this particular compromised key increased from 215 to 490. In total, the researchers identified about 20 different test keys, four of which were recently discovered.

An analysis of 10,095 unique firmware images using the Binarly tool showed that 8% (791 images) contained non-production keys. The problem affects not only personal computers, but also medical devices, game consoles, corporate servers and critical infrastructure.

All previously discovered keys were obtained from AMI, one of the three major providers of software development kits (SDKs) that device manufacturers use to customize UEFI firmware to work on their specific hardware configurations. Since July, Binarly has discovered keys belonging to AMI’s competitors, Insyde and Phoenix. Binarly also discovered that the following three manufacturers also sell devices affected by PKfail:

• Hardkernel Odroid-H2, Odroid-H3 и Odroid-H4
• Beelink Mini 12 Pro
• Minisforum HX99G

The vulnerability IDs are CVE-2024-8105 and VU#455367. PKfail does not pose a threat to devices that do not use Secure Boot, but it does undermine the security of systems where this protection is required, such as government contractors and enterprise environments.