How do I know if I have a virus? Getting rid of malware

You may be saying…

“I’m certain I have a virus! My machine is running really slow! How do I find it?”

Good instinct. Granted, sometimes devices run slowly because they are old, or because you’ve filled up their memory. But malware (the term usually used these days instead of “virus”) can also eat up your computer’s processor power. So it’s worth checking to see if that’s the problem.

Figuring out what the problem is

Your first steps are:

1. run your security software and

2. get a clearer picture of what’s going on.

Run your security software

Here’s where you go back to the name of your security software, which, as I said in Keep Calm and Log On, you should write down somewhere near your device so you can refer back to at times like this. Go looking for that name on your device, and run its scan to see if it turns anything up.

Don’t have security software, or don’t know if you do? Some devices today also come with built-in security scans. Here’s how to get to them on Microsoft. If you’re looking for add-on security scan software for Apple or Android devices, I recommend Malwarebytes.

For the most part, antivirus software will do a good job of removing malware which has snuck onto your machine. If it doesn’t turn anything up, it’s time to take further action.

OK, the scan didn’t find anything. What now?

It’s time to take a step back and figure out whether the device is just running slow because you’re running out of space on your drive, you have too many browser windows open, or you’re running too many apps at once. Here are some places you want to look, and what to do while you’re there:

• What is eating a lot of your memory?

  • Sometimes our machines run slowly because we just don’t have much space left on them. The first thing to check is how much disk space you have left. Here’s how to do that on Mac, Windows, Android, and iPhone (here’s a video for that last one), with some tips on managing space, too.

  • The rule of thumb is you should have 15% of your drive space free at any time. So if you have less than that left, it’s time to move some extra junk to the cloud or an external drive, or delete it.

• What is slowing your device down?

  • On most devices, you can get a look at what programs are running on the device. On a Mac, use the Activity Monitor. On a Windows machine, the Task Manager. Android devices may have processes running in the background. iPhones usually don’t.

  • Use those tools to see which programs are using more resources than others (they’re usually first in the list, and their numbers are much higher than others).

  • Write down the names of anything unfamiliar in those lists.

  • You’re now at the “Google the name” stage of the chart at the bottom of this article—go ahead and do some searching for the unfamiliar software.

  • Don’t delete anything yet—just hold on to your notes.

• What strange things start running when your device starts up?

  • Restart your device. If it’s a desktop or laptop, write down notes on what appears to start up when the machine starts up. This may be weird words in the all-text part when the Windows machine starts, or apps which bounce in the dock on your Mac. (This is like 80% of the work “experts” do when they fix your computer. Writing down the names of problematic software. I’m serious.)

• Now it’s time to take those notes and use them to figure out what’s going on:

  • If you’re running out of memory, a disk usage visualizer can help you easily see what’s hogging your memory. GrandPerspective is free for Mac. For Windows, I like TreeSize, but here’s a list of other disk usage tools, too. Take notes on the names of things using huge blocks of space, so you can delete them (if you know they’re not being used) or look them up to see if they’re related to malware.

  • If apps eating memory are ones you recognize, try quitting them and re-starting them.

  • Clear the cache in your browsers—here’s how to do it in Chrome, Safari on Mac and iPhone, Firefox, and Edge, or just poke around Clear My Cache until you find the answer.)

  • You may also want to clear cookies in your browsers, but be aware, this may log you out of some sites and forget other information you like to have stored in your browsers. But if browsing the internet is still going slowly for you, clearing cookies may help.

  • If you’ve found some suspicious software, it’s time to move on to the next step. You can do this yourself with these guides! But this is also a fine time to ask for help. Whoever is helping you will appreciate your notes, so bring them along.

Weed out malware by hand

This is not something you should do in every case. But if you see the same problem from the same malware over and over, it may be time to take more aggressive steps.

Bleeping Computer has a series of excellent step-by-step guides for removing some malware by hand, including ransomware (they even have anti-ransomware downloads to help you eliminate some kinds of ransomware—look in the security section of their downloads).

To use them, first use Bleeping Computer’s search engine on the name of the specific malware you’re seeing on your device. Sometimes you can even search for the wording you’re seeing in a strange error message, like “Can’t play this video!” or “Your Windows 10 is not updated” (they have guides with those messages as titles). Then follow the steps they list to weed out as many traces of the offending software as possible.

Keep defending your security “victory garden”

There are also a few browser extensions which can help block malware before it is installed. uBlock Origin helps fight malware by keeping ads from loading as you browse online. Ads are common sources of malware, as well as being drains on our attention. Here’s where to get uBlock Origin for Chrome, Microsoft Edge, and Firefox.

Ad Aware is also effective, but does not default to blocking all ads. You’d need to train it to block more things.

NoScript offers even more vigorous protection against malware, but you may need to add some sites to its trusted site list to keep things running smoothly.

But remember: no one device or app can protect your security. Your own security behavior is critical to protecting your digital valuables. For more tips, check the security section of this website, and take a look at Keep Calm and Log On.

You may be saying…

“Someone else usually does this for me. I’m not good at computers. I don’t know what’s malware and what isn’t!”

Look, nobody is born knowing how to fix a computer. Everyone who has helped you with your device has learned to do this at some point—and a lot of the time, the way they learned was by looking around in all the deepest parts of their machine to understand what it was doing. To be honest, most of the basic security settings on our machines are a matter of turning something on with a single button.

The cartoonist Randall Munroe provides this guide to how computer “experts” fix things:

This dangerous era of cyberattacks calls for us all to know more about the devices in our lives, to protect ourselves and our communities. It’s time to step up! For more tips on how you can support the global cybersecurity effort, check the security section of this website, and take a look at Keep Calm and Log On.