CVE-2023-43634 Config Partition Not Protected by Measured Boot

What is CVE-2023-43634?

CVE-2023-43634 is a high-severity vulnerability in EVE OS, published on 21 Sep 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

When sealing/unsealing the “vault” key, a list of PCRs is used, which defines which PCRs are used.

In a previous project, CYMOTIVE found that the configuration is not protected by the secure boot, and in response Zededa implemented measurements on the config partition that was mapped to PCR 13.

In that process, PCR 13 was added to the list of PCRs that seal/unseal the key.

In commit “56e589749c6ff58ded862d39535d43253b249acf”, the config partition measurement moved from PCR 13 to PCR 14, but PCR 14 was not added to the list of PCRs that seal/unseal the key.

This change makes the measurement of PCR 14 effectively redundant as it would not affect the sealing/unsealing of the key.

An attacker could modify the config partition without triggering the measured boot, this could result in the attacker gaining full control over the device with full access to the contents of the encrypted “vault”

Weakness: CWE-922, CWE-522

Which versions are affected by CVE-2023-43634?

3 open source packages ship an affected version, including github.com/lf-edge/eve. It affects 1 product.

Products include Lfedge Eve.

How do I fix CVE-2023-43634?

Upgrade github.com/lf-edge/eve to 0.0.0-20230519072751-977f42b07fa9 or later.

Is CVE-2023-43634 being exploited?

There is no known exploitation of CVE-2023-43634 in the wild and no public exploit code.

Other vulnerabilities in EVE OS

• CVE-2023-43633 Debug Functions Unlockable Without Triggering Measured Boot High 8.8
• CVE-2023-43637 Vault Key Partially Predetermined High 7.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-wc42-fcjp-v8vq, GO-2026-4432.