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How to Tell If Your Computer Has Been Hacked

Even if you're not a CEO or government official, hackers may be out to steal your private information. Here are the signs that you might be under attack, and what to do about it.

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Signs your computer was hacked

Living in a digital world has its perks, but it also comes with some risks. One of those risks: hackers accessing your smartphone and computer. You may have heard about hackers installing spyware on computers, but what exactly is spyware? “Spyware is any piece of software that collects and transmits information without the user’s consent and with covert methods,” shares Steven Solomon, co-founder and former CTO of Arcutek. It is used to gather information on a target, usually passwords, credit card, and financial information, system files, and, in extreme cases, keylogging and screen capture, he says.

Since hackers can get this sensitive information, it’s important to stay alert about what’s happening on your computer—especially if something odd comes up. Here are some signs your computer was hacked, and what you can do about it.

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Your computer starts running slower

If your computer suddenly starts taking forever to turn on or open up applications, that could be a symptom of malware infection, especially a worm or a Trojan horse, warns Sophie Miles, CEO and co-founder of “This happens because malicious software consumes too many CPU resources, which overloads your computer and causes it to run much slower than normal,” she says. However, computers can be slow for a host of other reasons, including lack of maintenance, full hard disk, overheating of the processor, and more, so it’s not a definitive sign that it has a bug. Here are the times you shouldn’t accept cookies on a website, by the way.


Your fans go into hyperspeed

“One the simplest ways to tell if a machine or mobile device has spyware, crypto-mining malware, or other viruses that consume processing power is paying attention to the physical temperature and battery life of the machine,” says Bill Siegel, founder of Coveware. So if your phone suddenly needs to be charged three or four times a day, its fan is running more than half the time, and it is always hot in your pocket or handbag, this can be a sign that malware is running and burning a significantly higher amount of CPU power. Don’t forget to bookmark these secrets from people who never get hacked—they really come in handy.

close up of a web cam on a laptop in a home settingWollertz/Shutterstock

Your webcam randomly starts recording

If your webcam or microphone turns on by itself that could be a sign of an infection, says David Geer from Geer Communications. And spies aren’t only trying to see you in an uncompromising position—hackers will try to catch your various passwords as you type them in. Something else to read up on: does taking Facebook quizzes put your information at risk?

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You see unknown sending and receiving lights

Another indicator that someone else is controlling your computer? “Blinking send and receive lights when your computer is idle is a warning sign,” says Jack Vonder Heide, president of Technology Briefing Centers, Inc. Make sure you know how to block emails, especially those spam ones that could put your device at risk.

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Your apps act up

“A known approach to data collection is injecting attacker code to the target application,” says Lindsay Hull, Senior Strategist at Zer0 to 5ive. The result is an app may run slowly or crash frequently. Heads up: if these apps are on your phone, someone may be spying on you.

Stylish African American black businessman types information from his credit card to the smartphone standing before a modern glass building outsideIVASHstudio/Shutterstock

You start seeing more pop-up ads

“If all of a sudden you have browser add-ins or plug-ins you don’t remember installing, your machine may be infected,” says Richard Ford, PhD, chief scientist at Forcepoint. “Often, these add-ins help an attacker monetize their access to your machine. Similarly, if the web now seems full of pop-up advertisements, you may be infected.” If you want to protect your privacy, here’s how to see (and delete) all of your Google activity.

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Your homepage changed

“If you open your web browser and are taken to an unfamiliar page instead of your normal homepage, or if you type a search term into your browser, and another browser pops up with a list of websites for your search term, this could be a sign of spyware,” says Stacy M. Clements of Milepost 42. “This is especially true if you realize your browser settings have been modified and you are unable to change the settings.” Here’s how to delete yourself from Google searches and regain a little privacy.

Hand of a man using laptop computer working overtime at his desk in the office late at nightAtstock Productions/Shutterstock

Mysterious tools start showing up

“Other signs of potential spyware are files appearing on your computer, or toolbars and tray icons that you didn’t install suddenly showing up,” Clements says. You may also find that your antivirus software or some system tools on your computer are unresponsive or don’t work properly. If you’re cleaning up your online life, here’s how to delete a good portion of your digital footprint.

business, overwork, people, deadline and technology concept - stressed businessman in glasses with laptop computer thinking at night officeSyda Productions/Shutterstock

Websites suddenly stop responding

“I’m not talking about one or two websites but multiple ones that aren’t related,” says Trave Harmon of Triton Computer Corporation. And if your co-workers or other people on your same network aren’t having any problems accessing these same sites, that’s an even bigger sign something is afoot. If you want to block certain websites, here’s a guide on how to block websites on Chrome.

young cell phone addict man awake at night in bed using smartphone for chatting, flirting and sending text message in internet addiction and mobile abuse conceptMilan Ilic Photographer/Shutterstock

You get a warning

“If an anti-virus warning pops up, don’t ignore it,” says Adam Dean, security specialist at GreyCastle Security. And don’t presume it has removed the virus, either. “If you see a malware detection by anti-virus software, assume it’s letting you know you have an issue, not that it has deleted the virus,” he says.

Businesswoman working at a laptop late at night in officeAntGor/Shutterstock

How to protect your computer from hackers

The best way to avoid infection is to have a solid, reputable antivirus/antimalware program installed on your computer, says Troy Wilkinson, CEO of Axiom Cyber Solutions. Fortunately, even advanced antivirus/antimalware solutions are not expensive. “These cost just a couple of dollars a month, so there really is no valid reason not to use one. But if you get infected, spyware can run hidden in the background, silently collecting your information and could cost you hundreds or thousands in the long run.”

Here are other tips for protecting your computer from hackers and spyware:

  • Avoid interacting with pirated material
  • Don’t open suspicious emails or click on suspicious links
  • Make sure you use strong passwords
  • Don’t use USBs that aren’t yours
  • Use a firewall
  • Keep your computer updated
  • Use multi-factor authentication

Next, learn how to tell if your phone was hacked and what you can do about it.


Joe McKinley
Joe McKinley is a regular contributor to Reader's Digest, covering cars, careers, tech and more.

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