Avast Academy Security Malware What Are Keyloggers and How Do They Work?

What Are Keyloggers and How Do They Work?

Usernames, passwords, bank account numbers, private messages: keyloggers capture all your keystrokes. Keep reading to learn what keyloggers are, how they work, and how to prevent them from spying on and capturing your personal data. Then, get a world-class security app to protect yourself against keyloggers and other malicious software.

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Written by Nica Latto
Published on October 22, 2021

What is a keylogger?

Short for “keystroke logging,” a keylogger is a type of malicious software that records every keystroke you make on your computer. Keyloggers are a type of spyware — malware designed to spy on victims. Because they can capture everything you type, keyloggers are one of the most invasive forms of malware.

There are two main types of keyloggers: software and hardware. Keylogger software is more common than keylogger hardware, because the latter requires actual physical access to a device.

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    Keylogger software

    Keylogger software is more common than keylogger hardware, because you don’t need physical access to a targeted device. Keylogger software works like other malicious software: it infiltrates your device through malicious links or attachments, or even exploits or Trojans. A keylogger runs silently in the background of your computer until you discover and remove it.

    Keylogger software is usually malicious, but some companies and parents use it to keep tabs on employees and kids. Depending on their application, time-tracking software and parental monitoring apps can easily verge into spying territory. When keyloggers are used to spy on loved ones, they’re referred to as stalkerware.

    What can keylogger software do?

    • Record all your keystrokes, including your passwords and credit card numbers.

    • Record both sides of conversations in messaging apps and emails.

    • Record your browsing and search history.

    • Take screenshots when certain keywords are typed.

    • Take remote control over your device.

    • Remotely log in or out of your device.

    • Record how long you use specific apps.

    • Print or email logs back to the hacker.

    • Hide in the background.

    Keyloggers record what you type, spying on your passwords, messages, and more.Keyloggers record what you type, spying on your passwords, messages, and more.

    Hardware-based keyloggers

    Hardware-based keyloggers take the form of a physical device, like a USB stick or another item that may look similar to a charger. They record keystrokes and other data, to be retrieved later by a hacker. Hardware keyloggers are difficult to detect with antivirus software.

    For a hacker to install a hardware-based keylogger, they must have physical access to your device. They’ll usually try to hide the hardware in the back of a desktop PC tower or somewhere else you’re unlikely to look.

    How do keyloggers work?

    Keyloggers work by sneaking onto your computer, often hidden inside a Trojan or other malware. A keylogger records your keystrokes in small files to be viewed by the attacker. The files may be periodically emailed to the hacker, uploaded to a website or database, or wirelessly transmitted.

    With hardware-based keyloggers, files may be stored on the computer until the hacker retrieves the keylogging device.

    Keyloggers hide on your device, recording your keystrokes and sending them back to the attacker.Keyloggers hide on your device, recording your keystrokes and sending them back to the attacker.

    Why keyloggers are a threat

    Because keyloggers can record everything you type, they pose a huge risk to your data security. A hacker with access to your usernames and passwords is just one step away from identity fraud, monetary theft, selling your private data on the dark web or to data brokers, exposing your personal info, and causing all kinds of other havoc.

    Keyloggers are one of the most dangerous forms of malware out there.

    Can keyloggers be detected?

    Yes, keyloggers can be detected, but it can be tricky. Like most types of malicious software, keyloggers are designed to remain hidden. The easiest way to detect malware is to use strong antivirus software that will detect and block keyloggers before they can infect your device.

    If you think you’ve already been infected with a keylogger, look out for the typical warning signs and use a malware removal tool immediately.

    What are the warning signs of keyloggers?

    The warning signs of keyloggers are similar to those for other types of malware. Here’s what to look for if you think you may have a keystroke logger on your device:

    • Slow performance. If your computer is suddenly transmitting all your keystrokes back to a hacker, your performance will take a hit across the board.

    • Unexpected crashes and freezes. All the processing power needed for recording can make your other apps crash and freeze more often than usual.

    • Changed settings. If you suddenly have a new browser homepage, toolbars, or icons, it could be a sign of malicious software like a keylogger.

    • Weird redirects. If you’re typing in searches and getting redirected to an unexpected search engine or web pages that don’t look quite right, it could be a malicious redirect.

    To find out if a keylogger is lurking on your machine, download a spyware removal tool. Avast One detects all kinds of spyware: keyloggers, infostealers, adware, and rootkits — and it will help you remove it in just a few clicks. Get protected by one of the largest threat-detection networks in the world so you’ll never fall victim to spies again.

    Are keyloggers illegal?

    The legality of keyloggers depends on consent — and keyloggers are illegal if content is not given. If you work for a company that uses employee monitoring or tracking software, you have to agree in your contract that you consent to this type of keylogging. Parents are legally allowed to monitor their children if they are under 18 years of age.

    Malicious keylogging by hackers against victims is illegal. The victim did not consent to be monitored, and keylogging is against several data theft, wiretapping, cybercrime, and hacking laws.

    It’s generally legal to install a keylogger on devices you own, but not on ones you don’t. Even letting someone borrow your computer without telling them about your keylogger is illegal. And using information obtained illegally from keylogging — such as usernames and passwords — for further crimes, like theft or fraud, can result in even harsher criminal penalties.

    Who uses keyloggers?

    Keyloggers aren’t explicitly malicious, and they are sometimes even used for legitimate purposes. Here are some of the people who might use keyloggers:

    • Parents: Some parental monitoring software is essentially spyware or even a keylogger. While it’s legal for parents to monitor their under-age children, it may harm family relationships. We recommend talking openly about internet safety with your kids.

    • Companies: Some companies use keyloggers (styled as “employee-monitoring software”) to track which apps employees use, and how they are using their time. But companies must get your consent to do this.

    • IT support: If you’re having an issue with your computer, the IT department may use a keylogger to watch what’s happening remotely to find a solution. But they also need your consent — and watch out for tech-support scams.

    • Law enforcement: Police may use keylogging software to track suspects’ activity — but they need authorization through appropriate search warrants.

    • Hackers: When most people think of keyloggers, they think of hackers.

    • Abusers: A disturbing trend, stalkerware is on the rise and keyloggers may be used in conjunction with intimate partner violence. See this guide to digital safety for intimate partner violence survivors if you need help.

    How to prevent keylogging

    The best way to prevent keylogging is to practice smart digital habits and hygiene. Putting these tips into practice will prevent keyloggers along with viruses, ransomware, adware, and other types of malware.

    Here’s how to prevent keylogging:

    • Get an ad-blocker and avoid clicking on pop-ups. Though rare, ads can be laced with malware, and it's a good idea to use an adblocker anyway.

    • Be wary of attachments. If a contact sends you an attachment you weren’t expecting, be careful before clicking. They may have been hacked and the attachment may execute malware clicked on.

    • Never give out personal information over email. Legitimate companies won’t contact you and ask for your password or other personal information. Such requests are likely phishing attempts — hackers trying to use social engineering methods to access your data.

    • Always install updates when they become available. Updates contain bug fixes and security patches that prevent exploits among other things.

    • Download software only from trusted sources. Third-party download sites may bundle legitimate software with bloatware or malicious software.

    • Don’t leave your devices unattended in public. A hacker could be lurking in the cafe, ready to install a software or hardware keylogger.

    • Use robust antivirus software. Installing a strong antivirus app is the best protection against all types of malicious software.

    Remove and prevent keyloggers with Avast

    Even the savviest internet users can be fooled by a determined hacker. But with Avast One, you’ll never be caught off guard. Avast One is cloud-light, award-winning malware-prevention software that will keep keyloggers far away from your keystrokes. Block malware and stop worrying about spies with Avast.

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    Nica Latto