• You can tell your computer has been hacked if you see frequent pop-up messages, mass emails sent from your account, or unexpected programs appear.
  • If your computer has been hacked, you run the risk of losing data, having your identity stolen, or suffering financial losses. 
  • Here are seven signs that your computer has been hacked and five steps you can take to prevent hacking. 

Computer hacking doesn’t only happen in the movies. Unless you take precautions and make your computer’s security a priority, it’s possible you can get hacked, which can result in lost or stolen data, ID theft, and worse. 

But what does getting hacked actually look like? The signs might be subtle, but they’re often easy to identify. You might find unexpected changes to your computer, sudden slow performance, and an increase in unwanted behavior like pop-up windows. Here are seven of the most important signs you’ve been hacked, as well as tips on how to protect your computer from getting hacked. 

Common signs of a hacked computer

There’s no single set of signals that you’ve been hacked, mainly because there are a lot of different ways you might be attacked. Here are seven ways to tell that you might have been hacked. 

Watch for pop-up messages and antivirus warnings

Pop-up windows warning you about viruses and malware attacks sound helpful in principle, but be sure you’re seeing an authentic message from the antimalware software you actually have installed before responding to or acting on its recommendations. The reality is that many of these messages are evidence that your computer has been hacked — infected with malware that’s masquerading as antivirus software. 

If you see any kind of unexpected warning message, don’t click. Instead, close your web browser and run your computer’s antimalware software to look for the presence of malicious software.

Unauthorized email sent from your account

One common goal of hackers is to infect as many computers as possible. One way to do that is to take control of email apps and email services, and use them to send infected email messages to as many people in the hacked address book as possible. A serious signal that you’ve been hacked: hearing from friends and colleagues that they’ve received spam from your email account. 

New programs installed on your computer

It’s not surprising that there are more programs installed on your computer than you regularly use. Your computer vendor may have pre-installed a lot of apps, for example. But if you suddenly discover unexpected apps running when you start your computer, or you see new programs in the taskbar or notification tray, then it’s likely you’ve been hacked or infected with malware, and these unknown programs are performing malicious acts on your PC. 

The startup apps list in Windows 11.

You can inspect the list of startup apps on your computer to see if there are any new or unexpected ones installed.

Dave Johnson

If the uninstaller does not work or you can’t otherwise remove these unknown programs, there’s a very good chance your computer has been compromised. 

Password and access changes to apps and services

In most cases, you should get an email or text message notification when your password or access settings change for common online apps and services — especially banking and other financial services. If you get emails notifying you about changes to your account settings that you didn’t request or authorize, that’s an enormous red flag that you’ve been hacked. Contact the financial institution or other service to see if you still have control of the account.

Be very careful, though. A common phishing trick involves sending a fake email about a password reset or some other account change. If you click a link or call the phone number in the message, you could be reaching out directly to the hackers, who will milk you for personal information and possibly get enough information to hack your account for real. When you follow up on a possible hack, always contact the service using an email or phone number you have found in the service’s app or on its website. 

Slow performance and frequent crashes

As your computer ages, it often starts to feel like it’s running more slowly than when you first brought it home, whether because Windows slows down or the hard drive fills up and doesn’t access data as efficiently. But if your computer suddenly starts acting weird — it slows down, crashes frequently, seems to get hotter than usual while running — then that might be a sign that your computer has been hacked and is running malware. Malware is typically buggy and inefficient, which can lead to poor performance and lots of crashes. 

Changes to your web browser

Did your web browser’s home page change without your permission? You might be hacked. Also, watch out for unexpected browser toolbars, plugins, and extensions, as well as a sudden increase in the number (and kind) of ads that your browser displays. Any of these are signs that you’ve lost exclusive control of your computer and hackers are installing malware in your browser. 

Unusual webcam activity

Your webcam has a status light that comes on when it’s in use. If you see your webcam come to life unexpectedly — such as when you are not using any web chat software — it probably means you’ve been hacked. Criminals may turn on the camera to see if they can read passwords as you enter them on the keyboard or see other personal information. 

How to prevent your computer from getting hacked 

Even though there are serious risks from hackers, a few common sense and simple precautions can protect you from hacks like these. 

  • Keep your operating system up to date. First and foremost, make sure that your computer’s operating system is up to date. Modern PCs and Macs install updates automatically, so make sure you don’t pause, disable or interrupt that process. For best results, don’t power off your computer after hours; put it to sleep so updates can install automatically when you are not using it. 

Windows Update in Settings.

Check your computer to make sure all the latest OS updates are installed.

Dave Johnson

  • Run antimalware software. Every computer should have antimalware and firewall software installed and kept up to date automatically. You don’t need an expensive third-party antivirus app; as long as you use the Windows Defender software that comes with Windows or XProtect for the Mac, you should be adequately protected. 
  • Always use strong passwords. When you create accounts for apps and services, always use strong and unique passwords. That means not repeating the same password on multiple accounts — if your online storage account is compromised, for example, hackers shouldn’t be able to use that login info to get into your banking app. And a strong password is a long string of numbers, letters, and symbols.  
  • Implement two-factor authentication (2FA). No matter how good your password is, take advantage of two-factor authentication for any app or service that offers it. This keeps someone who cracks your credentials from being able to access your account without having physical access to the device (like your phone) that you use for authentication. Any kind of 2FA is good, but using an authenticator app that generates one-time codes every time you want to log in is especially secure.

Authy two-factor authentication app for iOS.

Use two-factor authentication with an app like Authy to ensure you can’t get hacked using a username and password alone.

Dave Johnson

  • Don’t use public or unsecured WiFi. Most public WiFi networks are unsecured, which means your data can be intercepted while you’re online. Avoid using public WiFi, but if you must be especially wary of logging into services that require entering a password for access, and in particular avoid using banking and financial services.