Julia is a senior security analyst for Berber Consulting group. She is currently working on a contract for a small accounting firm in Florida. They have given her permission to perform social engineering attacks on the company to see if their in-house training did any good. Julia calls the main number for the accounting firm and talks to the receptionist. Julia says that she is an IT technician from the company's main office in Iowa.

She states that she needs the receptionist's network username and password to troubleshoot a problem they are having. Julia says that Bill Hammond, the CEO of the company, requested this information. After hearing the name of the CEO, the receptionist gave Julia all the information she asked for.

What principal of social engineering did Julia use?