What Are Keyloggers?

A keylogger is a program that records keystrokes and sends them to a third party for malicious purposes. The main difference between a keylogger and legitimate software is that a keylogger does not collect keystrokes for your benefit. Instead, the recorded keystrokes are used by an attacker for their own gain.

Within this definition, there are several different types of keyloggers.

Potentially Unwanted Keyloggers

A keylogger can be identified as a “PUP” (Potentially Unwanted Program). Unlike malware, which infects a computer without the user’s knowledge, PUPs are installed with the user’s consent. These programs are often marketed as legitimate tools for monitoring children or employees and, in theory, have legal uses.

However, these keyloggers are also frequently misused. An attacker with access to someone else’s device can install a keylogger without the owner’s knowledge for malicious purposes. This is common in cases of stalking, harassment, blackmail, and similar activities. As a result, most antivirus programs will detect these legitimate keyloggers as PUPs.

Adware Keyloggers

These keyloggers collect keystrokes in order to:

• Serve you targeted ads;
• Create a profile to better understand you as an advertising target;
• Gain insights into their customer base.

Such programs collect your browser search history and information about every website you visit. Adware keyloggers often go far beyond simple keystroke logging and may gather data such as your browsing history, browser name, installed software, user location, and more.

Typically, these programs trick users into installing them using various lures. For example, using an Adobe Flash Player installer is one of the most common methods, even now when Flash is obsolete. Usually, keyloggers are distributed as trojans—programs that users are deceived into downloading and running.

Malicious Keyloggers

This is the most dangerous category of keyloggers. These programs are designed solely to steal your information. Malicious keyloggers are often used to collect sensitive data such as login credentials, credit card numbers, Social Security numbers, and more.

Malicious keyloggers can infect your computer in several ways:

• Trojan installation via a lure or fake program;
• Device infection through a browser vulnerability that allows arbitrary code execution;
• Manual installation by an attacker who has physical or remote access to your machine.

Additionally, most malicious spyware is not limited to just keystroke interception and includes keylogging as part of a full suite of features, which may also include:

• File collection;
• Screen capture;
• Video and audio capture via webcam and microphone;
• Execution of arbitrary commands.

Therefore, most of these malicious programs are not just keyloggers, but fully featured spyware.

How to Protect Yourself from Keyloggers

• Use antivirus software;
• Set a strong password for your computer login;
• If others use your computer, create a separate user account for them and do not give them administrator rights;
• Be careful with what you download from the internet. Do not download anything from unknown websites;
• Keep your system up to date. Regularly install the latest updates.

Following these rules does not guarantee complete safety, but it will reduce your chances of infection and make it harder for attackers to install malicious software on your device.