CVE-2022-0358

A flaw was found in the QEMU virtio-fs shared file system daemon (virtiofsd) implementation. This flaw is strictly related to CVE-2018-13405. A local guest user can create files in the directories shared by virtio-fs with unintended group ownership in a scenario where a directory is SGID to a certain group and is writable by a user who is not a member of the group. This could allow a malicious unprivileged user inside the guest to gain access to resources accessible to the root group, potentially escalating their privileges within the guest. A malicious local user in the host might also leverage this unexpected executable file created by the guest to escalate their privileges on the host system.

Weakness

The product attempts to drop privileges but does not check or incorrectly checks to see if the drop succeeded.

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.

References

• https://access.redhat.com/security/cve/CVE-2022-0358
• https://bugzilla.redhat.com/show_bug.cgi?id=2044863
• https://gitlab.com/qemu-project/qemu/-/commit/449e8171f96a6a944d1f3b7d3627ae059eae21ca
• https://security.netapp.com/advisory/ntap-20221007-0008/