GAQM CPEH-001 Exam - Topic 3 Question 2 Discussion

Lori is a Certified Ethical Hacker as well as a Certified Hacking Forensics Investigator working as an IT security consultant. Lori has been hired on by Kiley Innovators, a large marketing firm that recently underwent a string of thefts and corporate espionage incidents. Lori is told that a rival marketing company came out with an exact duplicate product right before Kiley Innovators was about to release it. The executive team believes that an employee is leaking information to the rival company. Lori questions all employees, reviews server logs, and firewall logs; after which she finds nothing. Lori is then given permission to search through the corporate email system. She searches by email being sent to and sent from the rival marketing company. She finds one employee that appears to be sending very large email to this other marketing company, even though they should have no reason to be communicating with them. Lori tracks down the actual emails sent and upon opening them, only finds picture files attached to them. These files seem perfectly harmless, usually containing some kind of joke. Lori decides to use some special software to further examine the pictures and finds that each one had hidden text that was stored in each picture. What technique was used by the Kiley Innovators employee to send information to the rival marketing company?