CVE-2021-23240

selinux_edit_copy_tfiles in sudoedit in Sudo before 1.9.5 allows a local unprivileged user to gain file ownership and escalate privileges by replacing a temporary file with a symlink to an arbitrary file target. This affects SELinux RBAC support in permissive mode. Machines without SELinux are not vulnerable.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Potential Mitigations

• Follow the principle of least privilege when assigning access rights to entities in a software system.
• Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/132.html
• https://cwe.mitre.org/data/definitions/17.html
• https://cwe.mitre.org/data/definitions/35.html
• https://cwe.mitre.org/data/definitions/76.html

References

• https://bugzilla.suse.com/show_bug.cgi?id=CVE-2021-23240
• https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
• https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EE42Y35SMJOLONAIBNYNFC7J44UUZ2Y6/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GMY4VSSBIND7VAYSN6T7XIWJRWG4GBB3/
• https://security.gentoo.org/glsa/202101-33
• https://security.netapp.com/advisory/ntap-20210129-0010/
• https://www.sudo.ws/stable.html#1.9.5