What is Keylogger?

A Keylogger is a type of surveillance tool or malware that records a user’s keystrokes to secretly capture sensitive information such as usernames, passwords, or credit card numbers.

Expanded Explanation

Keyloggers can be implemented as software programs or physical hardware devices and are commonly used in both malicious cyberattacks and authorized security audits. Software-based keyloggers run covertly on the target system, often disguised as legitimate processes, and log all typed input to a file or remote server. Hardware keyloggers are typically inserted between a keyboard and computer, silently capturing keystrokes without requiring installation. While keyloggers are frequently associated with cybercrime—particularly credential theft—they are also used by ethical hackers during penetration tests to demonstrate the risks of unmonitored physical access and poor endpoint defenses. Advanced variants may also take screenshots, capture clipboard data, or monitor application activity.

Related Terms

Spyware, Surveillance tools, Credential harvesting, Physical device exploitation, Endpoint monitoring

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