Secure Boot Is Completely Broken On 200+ Models From 5 Big Device Makers

An anonymous reader quotes a report from Ars Technica, written by Dan Goodin: On Thursday, researchers from security firm Binarly revealed that Secure Boot is completely compromised on more than 200 device models sold by Acer, Dell, Gigabyte, Intel, and Supermicro. The cause: a cryptographic key underpinning Secure Boot on those models that was compromised in 2022. In a public GitHub repository committed in December of that year, someone working for multiple US-based device manufacturers published what's known as a platform key, the cryptographic key that forms the root-of-trust anchor between the hardware device and the firmware that runs on it. The repository was located at https://github.com/raywu-aaeon..., and it's not clear when it was taken down. The repository included the private portion of the platform key in encrypted form. The encrypted file, however, was protected by a four-character password, a decision that made it trivial for Binarly, and anyone else with even a passing curiosity, to crack the passcode and retrieve the corresponding plain text. The disclosure of the key went largely unnoticed until January 2023, when Binarly researchers found it while investigating a supply-chain incident. Now that the leak has come to light, security experts say it effectively torpedoes the security assurances offered by Secure Boot. Binarly researchers said their scans of firmware images uncovered 215 devices that use the compromised key, which can be identified by the certificate serial number 55:fb:ef:87:81:23:00:84:47:17:0b:b3:cd:87:3a:f4. A table appearing at the end of this article lists each one. The researchers soon discovered that the compromise of the key was just the beginning of a much bigger supply-chain breakdown that raises serious doubts about the integrity of Secure Boot on more than 300 additional device models from virtually all major device manufacturers. As is the case with the platform key compromised in the 2022 GitHub leak, an additional 21 platform keys contain the strings "DO NOT SHIP" or "DO NOT TRUST." These keys were created by AMI, one of the three main providers of software developer kits that device makers use to customize their UEFI firmware so it will run on their specific hardware configurations. As the strings suggest, the keys were never intended to be used in production systems. Instead, AMI provided them to customers or prospective customers for testing. For reasons that aren't clear, the test keys made their way into devices from a nearly inexhaustive roster of makers. In addition to the five makers mentioned earlier, they include Aopen, Foremelife, Fujitsu, HP, Lenovo, and Supermicro. Cryptographic key management best practices call for credentials such as production platform keys to be unique for every product line or, at a minimum, to be unique to a given device manufacturer. Best practices also dictate that keys should be rotated periodically. The test keys discovered by Binarly, by contrast, were shared for more than a decade among more than a dozen independent device makers. The result is that the keys can no longer be trusted because the private portion of them is an open industry secret. Binarly has named its discovery PKfail in recognition of the massive supply-chain snafu resulting from the industry-wide failure to properly manage platform keys. The report is available here. Proof-of-concept videos are here and here. Binarly has provided a scanning tool here. "It's a big problem," said Martin Smolar, a malware analyst specializing in rootkits who reviewed the Binarly research. "It's basically an unlimited Secure Boot bypass for these devices that use this platform key. So until device manufacturers or OEMs provide firmware updates, anyone can basically... execute any malware or untrusted code during system boot. Of course, privileged access is required, but that's not a problem in many cases." Binarly founder and CEO Alex Matrosov added: "Imagine all the people in an apartment building have the same front door lock and key. If anyone loses the key, it could be a problem for the entire building. But what if things are even worse and other buildings have the same lock and the keys?"

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