One of the company's IT security rules requires to logout the computers whenever or for whatever reasons the persons needs to leave their workstations.
Mary has worked in the organization for several years and knows the rules very well and never left her computer login during breaks or after work.
One morning she needed to leave her seat for seconds just to cross the room to grab a print, at the time the big boss walked in and jumped into Mary's computer to send out a group email to the department.
'to All, tomorrow, I'll buy everybody pizza for lunch, Mary'
Like this, Mary's boss hacked her computer.