CVE-2023-43631

SSH as Root Unlockable Without Triggering Measured Boot

Published Sep 21, 2023 CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Description

On boot, the Pillar eve container checks for the existence and content of
“/config/authorized_keys”.

If the file is present, and contains a supported public key, the container will go on to open
port 22 and enable sshd with the given keys as the authorized keys for root login.

An attacker could easily add their own keys and gain full control over the system without
triggering the “measured boot” mechanism implemented by EVE OS, and without marking
the device as “UUD” (“Unknown Update Detected”).

This is because the “/config” partition is not protected by “measured boot”, it is mutable, and
it is not encrypted in any way.




An attacker can gain full control over the device without changing the PCR values, thus not
triggering the “measured boot” mechanism, and having full access to the vault.



Note:

This issue was partially fixed in these commits (after disclosure to Zededa), where the config
partition measurement was added to PCR13:

• aa3501d6c57206ced222c33aea15a9169d629141

• 5fef4d92e75838cc78010edaed5247dfbdae1889.

This issue was made viable in version 9.0.0 when the calculation was moved to PCR14 but it was not included in the measured boot.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2023-48031 On boot, the Pillar eve container checks for the existence and content of “/config/authorized_keys”. If the file is present, and contains a supported public key, the container will go on to open port 22 and enable sshd with the given keys as the authorized keys for root login. An attacker could easily add their own keys and gain full control over the system without triggering the “measured boot” mechanism implemented by EVE OS, and without marking the device as “UUD” (“Unknown Update Detected”). This is because the “/config” partition is not protected by “measured boot”, it is mutable, and it is not encrypted in any way. An attacker can gain full control over the device without changing the PCR values, thus not triggering the “measured boot” mechanism, and having full access to the vault. Note: This issue was partially fixed in these commits (after disclosure to Zededa), where the config partition measurement was added to PCR13: • aa3501d6c57206ced222c33aea15a9169d629141 • 5fef4d92e75838cc78010edaed5247dfbdae1889. This issue was made viable in version 9.0.0 when the calculation was moved to PCR14 but it was not included in the measured boot.
Github GHSA Github GHSA GHSA-3mq9-xhgq-r7gj EVE: SSH as Root Unlockable Without Triggering Measured Boot
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
ASRG
Published
Updated
Sep 24, 2024, 5:41 PM
Reserved
Sep 20, 2023, 2:34 PM
Status
Modified
Published
Sep 21, 2023, 2:15 PM
Modified
Jun 17, 2026, 6:26 AM