Keyloggers explained: How attackers record computer inputs

What is a keylogger?

A keylogger is a tool that can record and report on a computer user’s activity as they interact with a computer. The name is a short version of keystroke logger, and one of the main ways keyloggers keep track of you is by recording what you type as you type it. But as you’ll see, there are different kind of keyloggers, and some record a broader range of inputs.

Someone watching everything you do may sound creepy, and keyloggers are often installed by malicious hackers for nefarious purposes. But there are legitimate, or at least legal, uses for keyloggers as well, as parents can use them to keep track of kids online and employers can similarly monitor their workers.

What does a keylogger do?

The basic functionality of a keylogger is that it records what you type and, in one way or another, reports that information back to whoever installed it on your computer. (We’ll go into the details in a moment.) Since much of your interactions with your computer—and with the people you communicate with via your computer—are mediated through your keyboard, the range of potential information the snooper can acquire by this method is truly vast, from passwords and banking information to private correspondence.

Some keyloggers go beyond just logging keystrokes and recording text and snoop in a number of other ways as well. It’s possible for advanced keyloggers to:

  • Log clipboard text, recording information that you cut and paste from other documents
  • Track activity like opening folders, documents, and applications
  • Take and record randomly timed screenshots
  • Request the text value of certain on-screen controls, which can be useful for grabbing passwords

What types of keyloggers are there and how do they work?

The term “keylogger” covers a wide variety of tools, some of which produce the same results in wildly different ways. We’ll drill down into the different types and talk a little bit about how they work.

The first general category is keylogger software. These are programs that live on your device and record your keystrokes and other activity.