title:  Config Partition Not Protected by Measured Boot
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”
problem types: CWE-522 Insufficiently Protected Credentials
affected:
{
defaultStatus: unaffected
packageName: EVE OS
product: EVE OS
programFiles: [https://github.com/lf-edge/eve/tree/master/pkg/pillar/evetpm/tpm.go, https://github.com/lf-edge/eve/tree/master/pkg/grub/rootfs.go, https://github.com/lf-edge/eve/tree/master/pkg/measure-config/src/measurefs.go]
repo: https://github.com/lf-edge/eve
vendor:  LF-Edge, Zededa
versions:
lessThan: 8.6.0, status: affected, version: 0, versionType: release
lessThan: 9.5.0, status: affected, version: 9.0.0, versionType: release
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: LOCAL
availabilityImpact: HIGH
baseScore: 8.8
baseSeverity: HIGH
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: LOW
scope: CHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
version: 3.1
]
format: CVSS
scenarios: GENERAL