5.9

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2023-43634

CVE-2023-43634: 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

(GitHub Advisory)

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CVE-2023-43634

CVE-2023-43634:

5.9

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
github.com/lf-edge/eve	go	< 0.0.0-20230519072751-977f42b07fa9	0.0.0-20230519072751-977f42b07fa9

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability, as described, is due to an incomplete set of Platform Configuration Registers (PCRs) being used to seal the disk encryption key. The configuration partition's measurement was moved to PCR 14, but the sealing process did not include this PCR. This allows for tampering with the configuration partition without invalidating the sealed key.

The analysis of the provided patch commit d9383a7ee4e1c39f5c8c6d4a63cb2ebd00695e8a confirms this. The commit modifies the DiskKeySealingPCRs global variable in pkg/pillar/evetpm/tpm.go to include PCR 14 and updates the hashing algorithm. This variable dictates which PCRs are used for sealing operations.

By inspecting the source code of pkg/pillar/evetpm/tpm.go, the function SealDiskKey was identified as the function that utilizes the DiskKeySealingPCRs variable to perform the sealing operation via tpm2.Seal. Therefore, SealDiskKey is the function that would be executing the vulnerable logic. During exploitation, an attacker would cause this function to seal a key without accounting for the state of the configuration partition (PCR 14), which could then be maliciously modified.

Vulnerable functions

SealDiskKey

pkg/pillar/evetpm/tpm.go

The `SealDiskKey` function is responsible for sealing the disk encryption key using a set of PCRs (Platform Configuration Registers). The vulnerability lies in the fact that the list of PCRs used for sealing, defined in the `DiskKeySealingPCRs` global variable, was incomplete. Specifically, it was missing PCR 14, which is used to measure the configuration partition. This omission would allow an attacker to modify the configuration partition without invalidating the sealed key, as the change would not be reflected in the PCRs used for sealing. The `SealDiskKey` function, by using this incomplete list of PCRs, creates a sealed key that is not properly protected against modifications to the config partition.

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WAF Protection Rules

WAF Rule

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Reasoning

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5.9

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Basic Information

Basic Information

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CVE-2023-43634: EVE Doesn't Protect Config Partition with Measured Boot

Impact

Patches

Workarounds

Resources

CVE-2023-43634:

5.9

-

Basic Information

Basic Information

Is this CVE running in your environment?

Technical Details

Technical Details

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Root Cause Analysis

Vulnerable functions

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WAF Protection Rules

WAF Rule

Reasoning

CVE-2023-43634: EVE Doesn't Protect Config Partition with Measured Boot

Impact

Patches

Workarounds

Resources

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

Basic Information

Basic Information

5.9

5.9

Technical Details

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