Malware affects us all.

The increasing number of Internet users worldwide creates an equal (or larger) number of opportunities for cyber criminals to take advantage of our systems. As we become more dependent on the online environment, we can clearly see a massive growth in malware and cyber criminal activities all across the globe.

total malware evolution

Source: McAfee Labs Threats Report, August 2015

With so many ways out there to access and exploit vulnerable systems, we need to make sure we’re able to recognize a malware infection in order to prevent and defend our systems. You need to know how to tell if you have malware!

Because it is a battle and you need to be ready.

This article will show you what the main symptoms of a malware infected system are. You’ll also learn to correctly evaluate the risk and know where to look for a solution. Let’s get to it!

Symptoms of a malware infection




slow computer

Does it take longer than normal for your operating system to boot up?
Are you waiting too long for some of your programs to start?

It is a known fact that malware has the tendency to slow down your operating system, your Internet speed or the speed of your applications.

If you notice something like this and you’re not using any resource-heavy program or application, check for other causes first. It may be a lack of RAM memory, a fragmented system, a lack of space on your hard drive or maybe a hardware issue affecting your drive. These 10 tips will come in handy when evaluating such problems.

If you have already thoroughly verified these possible causes and all seems fine, you can start considering a potential malware infection.





One of the most annoying signs of malware is represented by the unwanted pop-up windows. Unexpected pop-ups which appear on the system are a typical sign of a spyware infection.

In this particular case, the main issue is created not only by the numerous pop-up windows that affect your Internet navigation, but also because it is quite difficult to remove them from the system.

Pop-ups are not only annoying, but they usually come bundled with other concealed malware threats, and which could be far more destructive for our systems.

To avoid spyware and its impact on our systems, keep in mind a few security practices:

  • don’t click any suspicious pop-up windows
  • don’t answer unsolicited emails/messages
  • be careful when downloading free applications

To remove this type of threat, you need a very good security product against spyware. A few popular products capable of removing spyware from your system are Malwarebytes, Spybot Search and Destroy, Lavasoft’s Ad-Aware and others. This guide can help you get rid of this pesky problem.





If your programs or your system crash constantly or the infamous BSOD (Blue Screen of Death) appears regularly, it’s a clear warning that your system is not working properly and you should look into it.

There are two things that can cause this type of issues:

  • You could be dealing with a technical issue caused by a potential incompatibility between your software and/or hardware
  • Or it may be a malware issue.

If you suspect a technical issue, multiple software problems may lead to this.

Are you running various programs which may conflict with each other? Are there any orphan registry keys which have not been removed that could down and eventually crash your system?

If you are checking for malware, simply run a complete scan on the system with a good antivirus product. It is important to have a reliable security solution on your system, which should include real-time scanning, automatic update and a firewall.

To find the best solution, check the antivirus test results run by big company names in the security industry, such as AV Comparatives, PC Magazine, AV-TEST or Virus Bulletin and select the best antivirus solution for your system.




Another warning sign of a potential malware infection on your system is the hard drive activity.

If you notice that your disk continues to exhibit excessive activity even when you don’t use it and there is no program or download running at that moment, this could be the right time to check your system for malware.

We have to mention that another possible cause for the abnormal hard disk activity could be a hardware failure of the disk. You should also take this into consideration.




low disk space

Regarding the hard drive, you also need to check if your physical storage space has been increasing lately or if some of your files disappeared or changed their names.

This is another sign of malware activity, since there are numerous types of malicious software which use various methods to fill up all the available space in the hard drive and cause it to crash.





There are cases where the user is not connected to the Internet through his browser, and there is no program that may connect to online servers to download or upload any data,  but high network activity can still be observed.

First of all, we need to check the following:

  •  Is there any Windows update at that moment?
  •  Is there any program or application that’s downloading or uploading any data?
  •  Is there any update for a certain app running at that moment?
  •  Is there a large download that you started and forgot about, which may still be running in the background?

If the answer to all these questions is No, then maybe you should check where all that traffic is going.

  • To check for a malware infection, use a good antivirus product to check your system.
  • If you suspect that your computer has been infected by a dangerous financial malware, you need a specialized security suite designed to address these type of threats.




Have you noticed that your home page has been changed and you don’t remember doing it yourself?
Did a new toolbar pop out of nowhere and landed at top of your web browser?
Have you tried to access your favorite blog, but you were redirected to a different address?


This usually happens when you visit a website and you accidentally click a link or a pop-up window. This triggers unwanted software to download and install on your device. Its effects are not only annoying, but also malicious.

Run a complete scan with your security solution as soon as possible. Because these type of threats don’t go away easily. Make sure you run additional scans with specialized software, such as anti-spyware programs as the ones mentioned above.




A few warning signs should really make you suspicious. If any of these happen, pay closer attention and try finding the cause:

  • if, all of a sudden, you see programs opening and closing automatically
  • your Windows operating system shutting down without reason
  • if you notice strange windows in the booting process
  • or if Windows informs you that you’ve lost access to some of your drives.

Though the root cause may be a technical one, it could also be a sign that malware has compromised your system. If this is the case and you lost access to some important areas of your operating system, you need to prepare for the worst. These are the cases when a complete wipe and reinstall of the operating system is taken into consideration.




If your antivirus solution doesn’t seem to work anymore or if the Update module seems to be disabled, then check to see what happened immediately!

You should know that some types of malware are especially designed to disable security solutions, leaving you without any defense. If you already tried to reboot your computer, close and open the security solution and all your troubleshooting efforts were useless, you could consider the malware infection scenario.

This is especially the case since traditional antivirus solutions are sometimes unable to block and remove advanced malware, such as ransomware or financial malware. There are a couple of strong reasons why this is happening, and you should read about them, so you can enhance your protection by adding multiple layers.

For a more in-depth guide on how to remove all types of malware, not just spyware and adware, we recommend you check out our malware removal guide.




Are your friends telling you that they received suspicious emails from you or instant messages from your social media account, which often include attachments or links?


Source: Malware spread via Facebook chat

First of all, you need to verify whether those emails or messages were sent from one of your accounts (so check your Sent Items folder in your email/social media account). If there’s nothing there, those messages could have been delivered from an application which is out of your control.

If you discover the messages were sent from one of your accounts, take these steps:

  • Make sure you logged out from all your accounts. We access the same accounts on our work computers, on our home laptops and of course, on our mobile devices. Since we log in to our favorite online accounts on so many devices, it can happen that sometimes we forget to log out. Therefore, always make sure to log out from your online accounts on all devices.
  • Set strong passwords for your accounts. Don’t use the same password for all your accounts! Even if you are hacked, having different passwords for each account will help you limit a potential loss. Make a habit of managing your passwords safely.
  • Use two-factor authentication. This option can significantly increase your control over your accounts’ security. Using two-factor authentication means that, besides entering your credentials, you will also need to enter a code sent to your phone.


Knowledge is our best weapon


Knowing how malicious software behaves on a regular system may just prove to be the key element between staying safe and having your system wrecked or your online identity stolen.

Since we live in a connected and complex environment, online security doesn’t end with installing a series of security programs and forgetting about them. It’s essential that we also understand how malware behaves on the system, so we can mitigate its impact.

In the end, it is our knowledge of malware tools and methods that keeps us safe, because it is far easier to prevent a threat from becoming reality than to take actions against it when it’s already too late.

*This article was initially published by Aurelian Neagu in September 2014 and it was updated in May 2016.

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Good Article
keep it up
good to share for society,

[…] ZAHARIA, A. (2016, May 16). 10 Warning Signs that Your Computer is Malware-Infected [Updated]. Retrieved from Heimdal: […]

Hey Andra, Yday when i was browsing some genuine site, my laptop gives pop-up that malware detected. I updated default anti-virus system, what should i look more for? Hope my system is secure. Thank in advance.

Hi John! I’d recommend you use this guide to look into the issue more thoroughly:

sharanya patane on May 7, 2017 at 8:53 am

my connection is not secured my default home page has changed automatically i dont have access to select my homepage even youtube is not working

Mam/Sir, I would like to know Is there any powerful Total Security which is more effective than Malwarebyte to remove malwares and also my chrome browser keep showing these search engines “initialsite123” and “” and it’s so annoying, please help me how to remove these viruses??

Thank you!

hi i have a qustion my pc is keeps ruuning a scan disk then when i type in a explorer window i type in a web broswer and it reboots
also when i type something it goes to the next window without me pressing next
any help would be helpful

You can try this guide and see if you find anything malicious on your PC:

my home computer is really slow but we have really good internet.

Hi, I have a problem that I just cant find the solution to. My laptop is always connected to the WI-Fi. I have an antivirus program enabled. What happens is that even when I am not on the browser (like preparing a report in excel), even then my antivirus shows messages like “We have blocked this website for your safety”. And the trend is that most of those sites blocked are wordpress blogs that are probably spam. Just today, those sites turned into pornographic sites(and I might add ashamedly that the sites it tried accessing corresponding to my interests in that dirty field). It seems like my system is trying to access these sites in the background while also getting information and usage patterns on me and the antivirus is constantly blocking it. I have run two full scans, one in safe mode, one normally. Both times the scan showed no threats. Pls advise me what to do.

It seems like you could greatly benefit from what Heimdal PRO can do in terms of traffic filtering (which is more than the web traffic filtering in most AV products). But if you’d rather try another option, I’d recommend you try this guide and see if you find anything malicious on your PC:

I want to be a security system expert which course is best for me?


chantel williamson on March 15, 2017 at 11:11 pm

my computer is freezing like when you log on the mouse is stock and the websites wont open

Hi Chantel,

Sorry to hear that, but we don’t provide malware removal support. You can use this guide to start cleaning up your PC:


what if having immediately off while using your loptop? what the problem of this?

Found this while searching for a solution… but my issue is not on here. For the past week or so, every time we get on a search engine (we have google chrome, firefox and microsoft edge) (on a three-month old PC) it works at first, and then stops working…ALL of them! I ran free versions of malwarebytes…nothing, and superantispyware …cookies. I looked at programs in the control panel…nothing unusual popped up. When I restart the computer, I am able to get on the search engines. Using another device, I looked up possible solution, and for google chrome, it said to clear browsing history. I did, and that seems to have helped (I am on this site now!). I will try the same with the other search engines. But it seems that there should be something I need to clear off the computer. Any ideas?

Hello there! What I would do is also run a cleaning session with CCleaner. Maybe that can help.

You should try Google Cleanup Tool if you are still experiencing issues. URL:
Also, check on the extensions in each browser as you may potentially have adware such as unwanted toolbars. The Google Cleanup tool will scan your browser for known programs and will reset your browser “This will reset your startup page, new tab page, search engine, and pinned tabs. It will also disable all extensions and clear temporary data like cookies. Your bookmarks, history and saved passwords will not be cleared.”

You can also give Norton power Eraser a try, here is the URL:
When you use Norton Power Eraser, scan for unwanted applications then scan for risks. Save all of your files as you will be required to restart your computer for a rootkit scan. Do not go into the advanced settings unless you are considered an advanced user or a technician.

Hopefully, I helped in some way.

Great advice. I am going to share it with my students.

[…] you’ve been having these sort of symptoms and others like it, then there’s a very high chance your device might be malware infected. It’s certainly not […]

This is a good list. Some of these problems took me back a while. That IE toolbar picture is crazy haha. I think one of the most common one’s I see is the browser homepage being changed.

Another thing that catches a lot of people is the “Malware” that they install when installing another program. Spamming the next button can get you into trouble if one of those next buttons has a checked box that makes you agree to install something else. These have got me a couple times before as well.

I think we all fell for these at some point, just like you said, Dave. I’m glad you enjoyed the article and thanks for taking the time to share your thoughts!

Hi,my phone crashes on an app does that mean I have a virus also it says I have a virus and tells me to click on it do i

My phone has same issue, and other than that, my PC too gets hang up after 5 min usage. don’t know if both device are having virus attack.

Hi Andra. I have a quick question. If a pop-up appears on screen that says you are currently being hacked, should I trust those pop-ups if they aren’t from my anti-virus software? Thanks!

hi, in all my browsers( Mozilla, Google Chrome, Internet explorer) when i try to open “” or “ ” it gives me an error stating that ” your connection is not secure” pleases pleases help me to fix this, idont know what to do.

Hi there! Unfortunately, we can’t help with specific issues. Please verify your software and hardware for issues.

Are you currently a student using an account created by the school or your network administrator? (You may be the administrator) If so, log out of that account or start browsing in guest mode. That way, you can browse whatever you want. The same thing happened to a friend of mine. Oh, and another fix, do you currently see, or have. SafeMode enabled anywhere? If so, disable it. If there is no option to disable it, contact your network administrator or provider. Hope this helped!

I have a problem with my PC. I tried to download something and now something called arcing pops up and says it has stopped working. What should I do. I have a HP windows 10 laptop

Hi Alexander! We don’t provide assistance for malware infections for individual users, but you can certainly find help here: It seems that you’re infected with adware:

I’m using McAfee and Heimdal on my HP Laptop. My internet connection is 3G & have some speed problem. So patches are not updated many times. Should I need some more security software? Please suggest.

Hi there! I think that your internet provider may be the cause here. However, you can always send us an email at if you think we can help.

The disk continues to exhibit excessive activity even when you don’t use it…
I scanned with Malwarebytes Anti-Malware (updated) but the Heuristic Search
didint seek anything… anysuggestion?

Many things could cause this behavior, Roy, not only malware. It really depends on the hardware and software you use. Maybe someone from these forums can help:

Can a malware still don’t show these signs and lurk in the system?

Can you please help to suggest any best antivirus for my dell laptop ?

We actually have a guide dedicated to just that:

Can someone please help? I was on my laptop looking at a website and all of a sudden this thing popped up and it said: Your laptop has been hacked and blah blah blah and I don’t remeber the rest and I don’t know if it’s real or not. Please help.

So sorry to hear about your issues, Leen. I can’t tell by the details, but I’m sure you can find help on any of these great forums:

Most of those are scams designed to make you call a number in India to some boilerroom where they try and get you to give them access to your computer online, where they steal all of your personal information. I get these all the time—don’t ever call the phone number that they give you—it’s a scam.

how about Bug they keep showing up when i press a app

I can’t open some website, it said “What can I do to prevent this in the future?

If you are on a personal connection, like at home, you can run an anti-virus scan on your device to make sure it is not infected with malware. If you are at an office or shared network, you can ask the network administrator to run a scan across the network looking for misconfigured or infected devices.”

[…] you have spyware on your computer already, you need to find a program that removes the type of spyware you have on your system. There are […]

my computer suddenly gets distorted example the time in the right appears on the left behind the widows start menu and when my mouse rolls over icons they change pictures to other icons what is that whats wrong with my computer is it really because i didn’t upgrade to win10 and then reformatted my computer after all support for win7 stopped?? OMG I’m going nuts I reformatted my computer 5 times now.

Sorry, Teeri, but this looks like a problem you’ll have to contact Microsoft about (at first). Maybe you can use one of these forums to find help:

[…] And here’s how you can tell if your computer was infected with malware. […]

[…] following these basic rules and tips you will avoid most online threats such as phishing attempts, malware infections and so […]

hii.. i am using windows 8 ,sometimes it works so slow to loading the web page on internet and it also show with “Mozilla Firefox not responding”….what i do..please give any opinion on it,,your cute boy_ vicky

Hey i just bought a new gaming pc it has good ram and stuff but i installed a program that was claimed to be safe after using it i get a low framerate in games and my pc got too slow how it used to be ! i tried ti install Avast but it gives an error that file was corrupt or it was banned to be installed in my pc ! please help 😀

[…] that business owners and private internet users know the signs that their system has been hacked. Viruses can slip onto a hard drive undetected, but this is quite rare. In most cases, there will be a sign […]

[…] And here’s how you can tell if your computer was infected with malware. […]

really good post! Now i have a clear idea about viruses.

Can adware affect my bank account

No, but it can pave the way for other malware to infect your PC. Read more here:

mine keeps opening random tabs

Is computer malwares or virus can affect ups or other hardware attached?

Yes, it can, especially ransomware.

my computer keeps clicking randomly………

hai, i am using avast anti virus and it is updated monthly. does avast antivirus scans or identifies spyware ? and by using internet download manager ie , after the trail version of idm completed , i have installed the free trail version of idm by seeing tricks in the youtube ,by changing the existing trail version data in the windows run file.this type of shortcuts will harm the system ?

i brought a new pc,and now the antivirus shows me it has expired.
my sytem has been also slowed down ,it takes long time for the windows to boot.
and recently when i downloaded office 2016 from the net the sytem showed malware detected and asked me to restart the system.
i have got mccafee antivirus in my system
what should i do.
can u help me to figure out this problem?

We do not offer this kind of assistance, but maybe you can get some help here:

hi we have a net cafe and we have 5.5mbps internet connection then suddenly we experience low internet connections yesterday i conducted a speedtest we found out that our internet subscriber give only 1.22 mbps so we call thier attention thier technician arrive and test everything when they use their device a laptop the connection is fine its 5.5mbps but when our computer its only 1.22mbps they said that maybe some of our computer have virus they said thats the reason why whe have slow internet connection?is that possible? what would i do?we have 11 computers here…pls help me…..

We do not offer this kind of assistance, but maybe you can get some help here:

How to upgrade my HCL laptop RAM supporting DDR2 to DDR4 is it possible ?

when i open google or any sites on any browser .my antivirus shows a malware is blocked but my computer is very fast no pop-up messages are displaced .Is there anyone who can help me

[…] 10 Warning Signs that Your Computer is Malware-Infected [Updated] […]

Thank you for this information about knowing if a computer is infected or not. It is good to know that slow downs are a warning sign to pay attention to. This would be a problem because it could end up influencing the hard drive. Something to consider would be to seek professional help as soon as a problem is suspected.

Thrilled we could help, Jade! I hope you never have to deal with such an issue.

[…] and if you did get infected with malware, you most likely won’t notice. Second-generation malware, […]

[…] and if you did get infected with malware, you most likely won’t notice. Second-generation malware, […]

i got better solution to this all problem run them first in the virtual machine and leave it, in couple of minutes if strange happening to VM. or an annnoying pop-up to your screen, or system fails thats it its a malware.

Interesting. I have tried some scanning tools but most of them give you more malware. Do you know of any safe scanning software?

I will double check this symptoms in my PC. Ive experienced irregularities lately. Aside from ESET Antivirus, what other AV softwares can you suggest?

These are really helpful tips. Thanks for sharing. Most of these things were happened to me before. Then a friend recommends me to use ESET Antivirus and since then, none of these things are happening to my system anymore.

I was already familiar with all warning sings on the list, except #6 UNUSUALLY HIGH NETWORK ACTIVITY. I will be trying Glasswire now.

Patricia LongIsland on July 29, 2016 at 10:30 pm

I have a very unusual problem. There is one and only one website that I sometimes access where my letter U does not work at all. I try to leave a message or make comments and everywhere a letter U should be, there is nothing, not even a space. It’s like I just misspelled a word. Therefore, any message or comment I try to leave does not make sense. I have absolutely no other problems with my computer. Do you have any suggestions? Also, I use Google Chrome for Internet access. Thank you.

Hi Patricia,

This sounds very strange indeed. I couldn’t tell if it’s a hardware or a software problem, so I recommend you ask someone to take a look at it, because we don’t offer tech support and it’s difficult to offer specific advice from afar.

Best of luck!

I have had the very same issue mentioned above.. although it seems to have now gone away.. it was with Facebook messenger.. most frustrating as you can’t even type a Capital U to around the issue.

I believe it’s was Facebook but have been Viber ?

[…] 10 Warning Signs that Your Computer is Malware Infected … – How can you tell your system is infected with malware? Look for these 10 warning signs and learn what to do about them. […]

I have a problem before with malware. Usually when your computer is infected by it you will notice that your computer starts to slow. One way to address the problem is update your antivirus software and run a scan to rule out the problem. If you have time please check out Computer Repairs Adelaide

Marhasak DM Manurung on June 10, 2016 at 3:12 pm

when I connect my laptop to internet, everything on my computer are running slow. can you help me how to fix it?

Hi there,

Unfortunately, we don’t offer technical support. Please contact a company that provides this kind of services.

many possible why your PC so slow,one of that too many background process please your task manager what kind of apps eating your ram,processor, and hard disk space.
and terminate it,
if your PC, an regular apps become hungry of process power and ram sucker this the sign your PC infected of a malware, you run an anti-malware like malwarebytes

Glad I didnt have any of these things happening to my PC right now. I am using ESET Antivirus and im glad that my PC is still protected.

[…] behind advertisements attempting to convince users to either click them, inadvertently triggering malware installation, or download adware or fraudulent programs asking for personal […]

[…] And here’s how you can tell if your computer was infected with malware. […]

Thank you, very useful article.
My Laptop got slow when i uses any browser can you tell me what to do.

[…] Source: MalwareBytes , heimdalsecurity, kaspersky […]

How funny to run into a Romanian. I am a Romanian myself and I was researching an issue that I have with comments. Since a few days ago when I try to submit a comment on a blog, the computer is warning me that I am sending it on a form that is not secure. I have no idea what that means. Should I not send it? Does my computer have malware?

Hi Anda! So nice to have you here!
That sounds strange indeed. Our blog uses HTTPS, so the data you send us is encrypted for safety. Have you experienced this with other blogs as well?

Hi Anda,

Sorry that I only saw your comment now.

Our website is protected with SSL. Do you still have this issue? If so, we’ll look into it to make sure everything is in order.

Both Disqus and the Heimdal blog are safe to use, so maybe it was a temporary issue.

Thank you for your feedback!

and also check your internet connection, some problem laid to the internet provider

[…] For an increased protection, you can also relate to our articles on online safety, like The Ultimate Guide to Secure your Online Browsing and 10 Warning Signs That Your Computer is Malware Infected. […]

funny how I ran into a Romanian author 😀

[…] teach them to immediately get you or whoever in your house is the best with computers if anything starts acting funny on the computer screen. That way any problem can be stopped before too much damage is done by a […]

Updating operating system may improve the reliability speed and security of our computer. It is essential to improve and update your operating system from time to time. Latest version of OS allows you to do the updating automatically although may take a bit of time but it worth the effort.

[…] financial protection. We presented the main online scams that can be used against you and how to recognize a malware infection. But the fight against malware takes time and continuous knowledge since there’s a rapid […]

[…] for when if the antivirus kicks in (you should install this right after the initial setup) or for signs of malware infection and assure that them that they can give you a call anytime they have […]

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