CVE-2021-3917

A flaw was found in the coreos-installer, where it writes the Ignition config to the target system with world-readable access permissions. This flaw allows a local attacker to have read access to potentially sensitive data. The highest threat from this vulnerability is to confidentiality.

Weakness

During installation, installed file permissions are set to allow anyone to modify those files.

Affected Software

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/1.html
• https://cwe.mitre.org/data/definitions/127.html
• https://cwe.mitre.org/data/definitions/81.html

References

• https://access.redhat.com/security/cve/CVE-2021-3917
• https://bugzilla.redhat.com/show_bug.cgi?id=2018478
• https://github.com/coreos/coreos-installer/commit/2a36405339c87b16ed6c76e91ad5b76638fbdb0c
• https://github.com/coreos/fedora-coreos-tracker/issues/889