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

Vulnerability summary

CVE-2023-43634 is a high (CVSS 8.8) Insufficiently Protected Credentials vulnerability in lf-edge, zededa eve os. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 6.4% of scored vulnerabilities.

Timeline

1. 21-09-2023
   PublishedVulnerability first disclosed.
2. 24-09-2024
   Last modifiedVulnerability information updated.

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”

• CWE-522Insufficiently Protected CredentialsThe product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.
• CWE-922Insecure Storage of Sensitive InformationThe product stores sensitive information without properly limiting read or write access by unauthorized actors.