A company's IT security engineer has noticed several employees periodically checking their social media accounts. One such platform allows chat, which can include sharing links, photos, and videos. When the engineer casually observes one user about to click a link to view a video, she stops the worker. Afterward, she approaches the chief information officer $($CIO$)$ and advises that all social media accounts be blocked, and that only online training videos authorized by the company be allowed to be viewed. What threat is the IT security engineer concerned about?

Question $18$ options:

Spam

Trojan horse

Denial of service $($DoS$)$ attack

Covert channel