Privilege escalation is gaining a higher level of access than the account being used has been given. In hacker terms, this is called rooting the box. This comes from the UNIX/Linux world, where root is the administrator account. With this level of access, you own the box. In Windows systems, the administrator account has admin-level access and can do just about anything to the system. Still, in Windows, there is an even higher level of access, called system. With this account, you have full control over all levels of the system. This is the level of access that we want.
Gaining access to a user account is far easier than gaining the domain administrator's account in an attack. User accounts are far more numerous than administrator accounts, so snagging one of these off the wire (or wirelessly) is easier simply by the numbers. User accounts are...