Information
Its critical to limit users ability to set and effective authorization ID that is used with executing a view or stored program. This grant provides a method to escalate privileges within MySQL views and procedures. A user with this privilege can specify an non-existing account as the DEFINER attribute for CREATE PROCEDURE CREATE FUNCTION CREATE TRIGGER CREATE EVENT ALTER EVENT CREATE VIEW and ALTER VIEW
Later a user with escalated privileges could be created, providing unintended access rights which can be improperly used.
This permission is often needed temporarily when performing database migration. Once a migration is complete this permission is typically no longer necessary and should be removed.
Enabling a user to create a view, stored procedure or function and later create a user that improperly escalates privileges may provide unintended access rights which can be improperly used.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
Perform the following steps to remediate this setting:
- Enumerate the non-administrative users found in the result set of the audit procedure
- For each user, issue the following SQL statement (replace with the non-administrative user): REVOKE ALLOW_NONEXISTENT_DEFINER ON *.* FROM '<user>';