Описание
EVE Doesn't Protect Config Partition with Measured Boot
Impact
Config partition measurement was moved from PCR 13 to PCR 14 in a commit, but PCR 14 was not added to the list of PCRs that seal/unseal the vault key. As a result, an attacker can remove the disk, use another server to modify the files in the config partition, and then re-insert the disk.
Patches
Fixed in EVE version 9.4.3-lts
Workarounds
None (apart from preventing physical access to the device)
Resources
https://help.zededa.com/hc/en-us/articles/43295940828827-TPM-PCR-Index-Security-Implications https://github.com/lf-edge/eve/commit/d9383a7ee4e1c39f5c8c6d4a63cb2ebd00695e8a
Пакеты
github.com/lf-edge/eve
< 0.0.0-20230519072751-977f42b07fa9
0.0.0-20230519072751-977f42b07fa9
Связанные уязвимости
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”