With horizontal privilege escalation (or account takeover), an attacker gains privileged access to a standard user account with lower-level privileges. The intruder might steal an employee’s username and password, gaining access to email, files and any web applications or subnetworks to which they belong. Having obtained this foothold, the attacker can move horizontally through the network, expanding their sphere of privileged access among similarly privileged accounts.
Vertical privilege escalation (or privilege elevation) begins similarly, with an attacker using a foothold to try to escalate vertically, gaining access to accounts with higher privilege. For example, they might target accounts with administrator privileges or root access permissions, such as an IT helpdesk worker or a system administrator. A privileged account can be used to invade other accounts.