What are blocked and allowed lists used for in software security?

Blocked and allowed lists are fundamental security mechanisms employed to manage and control access to resources based on specified criteria. In the context of software security, these lists serve to permit or deny access to systems, applications, or data by evaluating the identity of users or entities attempting to gain access.

The primary purpose of an allowed list is to specify which entities are permitted to access certain resources, while a blocked list contains those that are explicitly prohibited from access. This approach aligns with the principle of least privilege, ensuring that only authorized individuals or systems can interact with sensitive resources, thereby reducing the risk of unauthorized access or potential security breaches.

By implementing these lists, organizations can effectively strengthen their security posture, as they clearly outline access control policies and help to mitigate risks associated with unauthorized access, data breaches, and other security threats.