Keylogger

A keylogger is a type of malware or hardware device that records every keystroke typed on a computer, capturing passwords, email content, documents, and anything else the user types. Software keyloggers run invisibly in the background, while hardware keyloggers are physical devices connected between the keyboard and the computer.

Keyloggers are a severe threat to CUI because they capture data as it's being typed — before encryption or access controls can protect it. They can capture credentials, allowing attackers to access systems as legitimate users, and they can record sensitive content being typed into documents and emails.