What is privilege escalation?

Privilege escalation is the process of exploiting vulnerabilities or misconfigurations in systems to elevate privileges from one user to another, typically to a user with administrative or root access on a system. Successful privilege escalation allows attackers to increase their control over a system or group of systems that belong to a domain, giving them the ability to make administrative changes, exfiltrate data, modify or damage the operating system, and maintain access through persistence, such as registry edits or cron jobs.

From a penetration tester's perspective, privilege escalation is the next logical step after the successful exploitation of a system and is typically performed by bypassing or exploiting authentication and authorization systems, whose purpose is to segregate user accounts based on their permissions and role.

A typical approach would be to use an initial access or foothold on a system to gain access to resources and functionality that is beyond what the current user account permissions offer. This process is commonly referred to as getting root privileges on a system.

Before we can get started with the various privilege escalation techniques, we need to understand how user accounts and permissions are implemented in modern operating systems.