What is a Keylogger?

Whether you’re interested in a career in cybersecurity or are simply looking for ways to protect yourself online, you might be asking “what is a keylogger?” Keyloggers belong to a category of malicious software, or malware, that records the individual keystrokes you make while using your computer. They can pose a serious threat to your online safety because they’re often used to capture private information, like passwords, credit card numbers and other sensitive data from individuals and organizations.

Fortunately, there are ways to defend against these malicious attacks using some cyber security basics. In this article, we’ll explore how keyloggers work, the different types of keyloggers, who uses them, how to detect them and what you can do to protect yourself in the following sections:

Keystroke logging is a well-established diagnostic tool with many legitimate uses. It’s the act of tracking and recording every stroke of a computer’s keyboard and is often done without the computer user’s knowledge or consent. When a computer keyboard is used, each keystroke sends a signal that tells the computer’s operating system and the application the user is running what to do. This communication is intended to be kept between computer and user. But when a keylogger is introduced as spyware to record every keypress and command, personal information like passwords, bank account and social security numbers, credit card information, email messages and logins could wind up in the hands of criminals. 

If you’re still asking “what is a keylogger,” understanding the two basic types of keyloggers can help. The two types of malware known as keyloggers are software keyloggers and hardware keyloggers. The software variety can spread from one computer to another over a network. Its hardware counterpart does not have this capability, but can still transmit information to the cybercriminals behind the attack.

Commonly used by hackers to record computer users’ keystrokes, software keyloggers have to be downloaded by the user via an infected application of some kind. Once installed, the keylogger records the user’s keystrokes and automatically transfers this information to the hackers using a remote server. 

A hardware keylogger must be physically connected to the target computer to do its work. An unauthorized person using a device on a network could install a hardware keylogger that could run undetected until after it finished collecting the sensitive information it was seeking. When finished logging keystrokes, the keylogger stores the data and the hacker has to download it from the device.

Unlike the software keylogger, the hacker is not able to get the data while the keylogger is working, but may be able to retrieve the data from the computer remotely by making it accessible via a Wi-Fi connection.

Keyloggers are used for both legal and criminal purposes. They can be used in a variety of legitimate ways related to product development, research or employee or parental monitoring. As noted above, they can also be used by malicious hackers and other cybercriminals to steal information.

They are sometimes used lawfully by:

Software keyloggers can be hard to detect and remove, even by some antivirus programs. They hide deep in your computer’s operating system, at the keyboard API level or in the computer’s memory. Often appearing to be normal files or traffic, this type of keylogger is even capable of reinstalling itself.

With hardware keyloggers, eradication could be either very simple or extremely complex. If the source of the malicious material is an external device, like an external hard drive, you can simply remove the device manually. An internal hardware keylogger, however, makes things much more difficult, potentially requiring a device teardown to discover.

Symptoms that might indicate the presence of a keylogger on your computer are similar to other virus warning signs and may include:

You can help protect yourself from keyloggers in many of the same ways you protect yourself from other cyber security threats: