Final answer:
The default security level for access controls should be 'No access' following the Principle of Least Privilege, which minimizes the risk of unauthorized access by only granting necessary permissions as needed.
Step-by-step explanation:
The default level of security for access controls should be the most restrictive, which is typically 'No access' or 'Least privilege'. This concept is part of a foundational principle in security called the Principle of Least Privilege (PoLP), which dictates that by default, access rights for users, systems, and applications should be limited to the minimum necessary to perform their tasks. When a new account is created or a new system is brought into an environment, it should not be granted any access rights until those rights are necessary and justifiable.
Over time, as a user or system's role changes, permissions can be adjusted to accommodate those changes. By starting with no access, organizations can maintain a tighter control over their resources and reduce the risk of unauthorized access or data breaches. Implementing this strategy is a key aspect of robust IT governance and risk management practices.