How to tell if your computer is hacked

A hacked computer usually shows itself through slowness, unexpected pop-ups, changed settings, or programs running without your permission. The most reliable signs are a spike in network activity when you are not using the machine, unfamiliar programs in your installed software list, or a browser that redirects you to sites you did not click. If your antivirus software is disabled and you did not disable it, that is a strong indicator someone else has access.

Not every slow computer is hacked—age, dust buildup, and too many programs at startup cause slowness too. But when slowness arrives suddenly alongside other signs, or when your antivirus reports threats it cannot remove, you are likely dealing with malware or unauthorized access rather than normal wear.

Key Takeaways

  • Sudden slowness, unexpected pop-ups, disabled antivirus, and unfamiliar programs in your software list are the most common signs of a compromised computer.
  • Check your Task Manager (Windows) or Activity Monitor (Mac) to see which programs are running and how much network traffic they are using.
  • Run a full scan with your antivirus software in Safe Mode, where fewer programs load and malware has less protection.
  • Change your passwords from a different device while your computer is offline, because malware can capture keystrokes on the infected machine.
  • If your antivirus cannot remove the threat or your computer remains compromised after scanning, contact a local repair shop or IT professional for hands-on removal.

Unexpected slowness and freezing

A hacked computer often runs slowly because malware consumes processor power and memory in the background. You might notice the machine takes longer to open files, applications freeze mid-task, or the entire system becomes unresponsive for seconds at a time. This slowness typically appears suddenly rather than gradually—yesterday it was fine, today it crawls.

To check what is using your resources, open Task Manager on Windows (press Ctrl+Shift+Esc) or Activity Monitor on Mac (Applications > Utilities > Activity Monitor). Look at the CPU and Memory columns. If a program you do not recognize is using 20 percent or more of your processor, or if the total memory usage is very high even though you have only a few windows open, something is running without your knowledge.

Legitimate programs sometimes spike in resource use during updates or large file operations. But if an unknown program stays at high usage for hours, or if you cannot identify what it is, that warrants investigation.

Pop-ups, redirects, and changed browser behavior

Malware often hijacks your browser to show advertisements, redirect you to malicious sites, or capture your search queries. You might see pop-ups that appear even when no browser window is open, or your search engine might change to one you did not set. Your homepage might redirect to a different site, or clicking a legitimate link takes you somewhere else entirely.

Check your browser settings by opening your browser's menu (usually three horizontal lines in the top right corner) and selecting Settings or Preferences. Look at your homepage, search engine, and installed extensions. If you see extensions you do not remember installing—especially ones with generic names like "Helper" or "Optimizer"—those are often malware. Uninstall them when ready.

Some malware also modifies your hosts file, a system file that tells your computer which web addresses to block or redirect. This requires more technical steps to fix, which is when calling a professional becomes the practical choice.

Disabled antivirus and security warnings

Malware frequently disables your antivirus software so it can operate without being detected. If you open your antivirus program and see that protection is turned off, or if the software will not start at all, that is a strong sign of infection. Similarly, if Windows Defender (on Windows) or your antivirus reports threats but cannot remove them, the malware has likely dug in deep enough to resist automatic removal.

Some malware also generates fake security warnings—pop-ups claiming your computer is infected and asking you to click a link or read a "fix." These are scams designed to trick you into installing more malware. Do not click them. Close the pop-up by clicking the X button, not any button within the pop-up itself.

If your antivirus is disabled and you did not disable it, restart your computer in Safe Mode with Networking (Windows) or Safe Mode (Mac). In Safe Mode, fewer programs load, which gives your antivirus a better chance to run and scan without interference.

Unfamiliar programs and startup items

Open your list of installed programs and look for anything you do not recognize. On Windows, go to Settings > Apps > Apps & Features. On Mac, open Applications in Finder. Malware often installs under vague names like "System Optimizer," "PC Cleaner," "Browser Update," or random strings of letters and numbers.

Also check what runs when your computer starts. On Windows, press Ctrl+Shift+Esc to open Task Manager, then click the Startup tab. Disable anything you do not recognize by right-clicking it and selecting Disable. On Mac, go to System Settings > General > Login Items and remove unfamiliar programs from the list.

Uninstall suspicious programs through your normal uninstall process (Add/Remove Programs on Windows, or drag to Trash on Mac). If a program refuses to uninstall, or if uninstalling it does not stop it from running, that is a sign the malware has embedded itself deeply and may need professional removal.

Network activity and unusual account behavior

Malware often sends data out of your computer without your knowledge—stealing passwords, browsing history, or personal files. You might notice your internet is slow even though you are not downloading anything, or your monthly data usage is much higher than usual. Some routers show a list of connected devices; if you see devices you do not recognize, someone may have gained access to your network.

Check your online accounts for unfamiliar activity. Log into your email, banking, and social media accounts from a different device and look at recent login history or active sessions. If you see logins from locations you were not in, or at times you were asleep, someone has your password. Change it when ready from the other device, using a strong password you have never used before.

If your email account shows recovery options (backup email address or phone number) that you did not set, change those too. Hackers often add a recovery option so they can regain access even after you change your password.

What to do if you think you are hacked

Start by running a full antivirus scan in Safe Mode. Restart your computer and enter Safe Mode (on Windows, restart and press F8 or Shift repeatedly during startup; on Mac, restart and hold Shift). Open your antivirus software and run a full system scan. This may take an hour or more, but Safe Mode gives the scan the best chance to find and remove malware.

While the scan runs, change your passwords from a different device—a phone, tablet, or another computer. Do this for email first, then banking, then social media and other accounts. Use passwords you have never used before and make them at least 16 characters long with a mix of letters, numbers, and symbols. Do not change passwords on the infected computer, because malware may be logging your keystrokes.

If the antivirus scan finds and removes threats, restart your computer normally and run another scan to confirm the infection is gone. If the scan finds threats it cannot remove, or if your computer remains slow and unstable after scanning, contact a local computer repair shop or IT professional. Removing deeply embedded malware often requires manual intervention that antivirus software alone cannot handle.

When to call a professional

You should contact a repair technician if your antivirus software cannot remove detected threats, if your computer remains compromised after a full scan, if you cannot access your antivirus software at all, or if you are not comfortable working in Safe Mode or Task Manager. A professional can use specialized tools, perform a deeper scan, and in some cases rebuild your system from scratch if the infection is severe.

Choose a local, established repair shop rather than calling a number from a pop-up or email. Ask friends or family for recommendations, or search for computer repair services in your area with reviews on Google or Yelp. Expect to pay a diagnostic fee (usually $50 to $150) before they tell you what is wrong and what removal will cost.

If you suspect your financial accounts have been compromised, also contact your bank and credit card companies. They can monitor for fraudulent activity and may issue you new cards or accounts.

Frequently Asked Questions

Can I get hacked just by visiting a website?

Yes, but it is uncommon. Visiting a legitimate website is usually safe. Clicking links in suspicious emails, downloading files from untrusted sources, or visiting sites known for malware distribution is much riskier. Keeping your browser and operating system updated patches security holes that malware exploits.

Does restarting my computer remove malware?

Restarting removes malware from your computer's memory temporarily, but most malware reinstalls itself when you restart because it has modified system files or startup programs. A restart can buy you time to change passwords or back up important files, but it is not a fix on its own.

Is my Mac safe from hacking?

Macs can be hacked, though less frequently than Windows computers because fewer people write malware for Mac. The same signs explore: unexpected slowness, unfamiliar programs, disabled security software, and unusual account activity. The steps to check and remove malware are similar, just using Mac-specific tools like Activity Monitor and System Settings.

What if I cannot afford to take my computer to a repair shop?

Run a full antivirus scan in Safe Mode first—this is free and removes many common infections. If that does not work, some nonprofits and libraries offer low-cost or free computer repair services. Search online for "free computer repair [your city]" or call your local library to ask about resources.

Should I wipe my computer and start over?

Wiping your hard drive and reinstalling your operating system is the most thorough way to remove malware, but it erases everything on your computer. Only do this if antivirus scans and professional removal have failed, or if you suspect your files themselves have been compromised. Back up any important files to an external drive first, then contact a professional to handle the reinstall.