Which principle should be used when granting user access to systems within the Cardholder Data Environment (CDE)?

The principle of least privilege is crucial when granting user access to systems within the Cardholder Data Environment (CDE). This principle ensures that users are granted only the minimum level of access necessary to perform their job functions. By limiting access in this way, organizations reduce the risk of unauthorized access to sensitive cardholder data, helping to maintain compliance with PCI DSS requirements.

Utilizing the least privilege principle minimizes potential damage in cases where user accounts are compromised, as attackers will have access to only a limited set of data and functionalities. This also aids in managing access control effectively, as it make it easier to audit and monitor users’ actions within the system.

In contrast, options like full access or open access can expose sensitive data to unnecessary risk, as they grant extensive permissions that are not aligned with users' specific job responsibilities. Role-based access, while it can be effective, may still lead to broader access if roles are not rigorously defined and limited according to the least privilege principle. Therefore, least privilege stands out as the most robust approach for securing the CDE.