Least privilege

Least Privilege is a fundamental security principle stating that users, applications, or systems should only have the minimum level of access (privileges) required to perform their legitimate tasks—and nothing more. 

If a marketing user only needs to view campaign data, they shouldn’t be able to edit system configurations. If an application only requires read access to one database table, it must not have admin rights over the entire database. The concept traces back to early operating system design (like in the 1970s with MULTICS), aiming to limit damage if any account is compromised or misused. 

In practical terms, least privilege is implemented via carefully scoped permissions, role-based access, or attribute-based rules. It’s an ongoing process: as tasks change, privileges must be updated or revoked. Many frameworks (NIST SP 800-53, ISO 27001) reference least privilege as a core requirement for robust security posture.

How does it affect identity security?

If an attacker compromises an account with minimal rights, the damage is limited because that account cannot escalate or access sensitive data by default. In contrast, if users or services have broad or admin-level access, a single stolen credential can lead to catastrophic breaches. Thus, least privilege reduces the attack surface and containment. It also mitigates insider threats: even malicious insiders can do less harm if their privileges match their actual job. 

Real-world breaches (Target in 2013, Equifax in 2017) often hinged on excessive or incorrectly assigned privileges that let attackers pivot deeper. Adopting strict least privilege policies ensures identity security is more resilient—each identity can only do what is necessary. This principle also fosters better accountability: logs become more meaningful if each user can only act in their rightful domain. 

Overall, least privilege forms the backbone for many identity security strategies like zero trust, layered defense, and compliance with regulatory demands for minimal data exposure.

Case studies

Attackers initially stole credentials from Target’s HVAC contractor, who had remote access beyond just environmental controls. Once inside, hackers accessed PoS systems, stealing 40 million card records. If that vendor account had been restricted (e.g., limited to separate network segments), the breach scope might have been vastly smaller.

Another example is the Ubisoft 2020 internal hack where an attacker abused an overprivileged internal account to pivot across Ubisoft’s internal network. The credentials should have only provided partial access to a specific project environment, but misconfigurations allowed wide reading rights. In both cases, ignoring least privilege gave attackers broader or deeper infiltration.

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