A keylogger, also known as keystroke logger or keyboard capture, is a type of surveillance technology used to monitor and record each keystroke on a specific computer or mobile device. Keyloggers can be either hardware or software-based, and they can be used for legitimate purposes like feedback for software development, IT troubleshooting, or employee monitoring. However, they can also be misused by cybercriminals to steal personally identifiable information (PII), login credentials, and sensitive enterprise data.

Hardware keyloggers are physical components built-in or connected to a device, and they can track keystrokes without even being connected to the device. On the other hand, software keyloggers are malware that can be installed on a device either purposefully or unwittingly. Once installed, the keylogger records every keystroke made on the device and periodically uploads the information over the internet to whomever installed the program.

There are different types of software-based keyloggers, including:

• API-based: These keyloggers hook keyboard APIs inside a running application. The keylogger registers keystroke events as if it was a normal piece of the application instead of malware. The keylogger receives an event each time the user presses or releases a key.

• Kernel-based: A keylogger using this method can act as a keyboard device driver and gain access to any information typed on the keyboard as it goes to the operating system.

• Form-grabbing: This type of keylogger is designed to capture data entered into web forms, including login credentials, credit card numbers, and other sensitive information.

To protect against keyloggers, it is recommended to use anti-malware software, keep software and operating systems up to date, and avoid downloading software from untrusted sources.