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vulnrichmentASRGVULNRICHMENT:CVE-2023-43630
HistorySep 20, 2023 - 2:37 p.m.

CVE-2023-43630 Config Partition Not Measured From 2 Fronts

2023-09-2014:37:44
CWE-328
CWE-522
CWE-922
ASRG
github.com
1
config partition
measured boot
sha1
sha256
pcr14
vault key
device control

CVSS3

8.8

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

AI Score

6.9

Confidence

Low

SSVC

Exploitation

none

Automatable

no

Technical Impact

total

PCR14 is not in the list of PCRs that seal/unseal the “vault” key, but
due to the change that was implemented in commit
“7638364bc0acf8b5c481b5ce5fea11ad44ad7fd4”, fixing this issue alone would not solve the
problem of the config partition not being measured correctly.

Also, the “vault” key is sealed/unsealed with SHA1 PCRs instead of
SHA256.
This issue was somewhat mitigated due to all of the PCR extend functions
updating both the values of SHA256 and SHA1 for a given PCR ID.

However, due to the change that was implemented in commit
“7638364bc0acf8b5c481b5ce5fea11ad44ad7fd4”, this is no longer the case for PCR14, as
the code in “measurefs.go” explicitly updates only the SHA256 instance of PCR14, which
means that even if PCR14 were to be added to the list of PCRs sealing/unsealing the “vault”
key, changes to the config partition would still not be measured.

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”

CVSS3

8.8

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

AI Score

6.9

Confidence

Low

SSVC

Exploitation

none

Automatable

no

Technical Impact

total

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