Which term describes the act of a user, without authority or permission, obtaining rights on a system, beyond what were assigned?

Authentication tunneling refers to encapsulating authentication protocols within other protocols for transport, not to unauthorized rights acquisition.

Administrative abuse describes the misuse of legitimately granted administrative rights, not the act of obtaining rights that were never assigned.

Rights exploitation is not a recognized standard security term for this concept - it has no formal definition in security frameworks or certification bodies.

Privilege escalation describes the act of a user exploiting a vulnerability, misconfiguration, or design flaw to obtain permissions beyond those officially assigned. Vertical privilege escalation involves gaining higher-tier access such as administrator or root, while horizontal escalation involves accessing resources of another user at the same level. This is a foundational concept in attack methodology and access control security.