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January 28, 2016updated 30 Aug 2016 3:11pm

How to tell if your computer is infected with malware

List: Computer crashing? Annoying pop-ups? Disabled anti-virus? All these signs point to malware.

By Ellie Burns

Malware is an umbrella term used for a variety of malicious software such as spyware, ransomware, viruses, worms, adware – the list goes on and on. The industry is clear in illustrating the dangers and threats posed by malware – but how can you tell if your system is infected?

CBR runs down the symptoms of a malware infection, giving you the key signs to watch out for if malware strikes your device.

1. Slow speed

This is the first sign you should always watch out for. After checking that it is not your RAM memory or other technical issues, your system slowdown is a clear sign of malware, as Mike Hickson, Managing Director of LSA Systems, told CBR:

"One of the simplest and earliest malware warning signs is your computing operating at an unusually slow speed. A computer that is slowing down due to excess programmes and data transferrals, when you have closed down all of the known open programmes is one key indicator of a malware infection. However, this is one of the first things overlooked by many people. Paying attention to the speed of your computer is one of the earliest ways to catch a malware infection as well as one of the simplest."

2. Annoying Pop-ups

A sign of a typical spyware infection is unexpected pop-ups, but the dangers of pop-ups are two-fold. One, the unsolicited pop-ups impact your internet navigation and secondly, and more importantly, they may be hiding other malware threats. These hidden malware threats which are concealed by the pop-ups could prove much more destructive than the annoying pop-ups.

David Flower, MD EMEA at Bit9+Carbon Black, told CBR: "Endpoint devices such as computers and laptops are not necessarily covered by traditional anti-virus (AV) software or firewalls, as these are rarely capable of dealing with the increasingly sophisticated standards of malware that are becoming more common. Malware can also very easily get around these defences through a phishing attack, which we have seen becoming far more convincing than they have been in the past."

Spyware infections are notoriously hard to get rid of, needing strong security products to clean your system. Malwarebytes and Spybot are just two companies offering such products.

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If you do get hit by pop-ups remember – never click!

Pop-up malware


3. Computer crashes & problems with programs

Do you frequently experience crashes, resulting in a red rage and the slamming of your computer mouse? Moving past the huge annoyance of computer crashes, the issue may be more than a simple technical issue. Malware may be the cause of the crashes, which means you have to act quickly. You must run a complete scan on your system and check your firewalls.

Another clear sign of malware is if you find that your security, like your anti-virus, has been disabled. Some malware is designed purely to disable such security programs, leaving your system wide open to other malicious software. In the same vein, you may also see programs which you don’t remember having installed suddenly appearing in your start menu.

This is another clear sign of malware, as Chris Boyd, Malware Intelligence Analyst at Malwarebytes, told CBR: "You may also see toolbars, desktop apps, and programs you don’t remember installing in your start menu.

"Malware can be a lot stealthier with regards detection, but random crashes, slowdowns and security software becoming randomly disabled can be key indicators."

Bolster you computer security with added software to add another layer of defence to this type of malware.


4. Unwanted Browser Revamp

If you have not followed our advice on pop-ups, and have been clicking, you may be seeing changes in your browser which you did not want, and did not need. Have toolbars been added to your browser? Is your default browser page directing you elsewhere? Are you being overwhelmed by redirects? If the answer to these questions is yes, then you may have malware on your system. As Piers Wilson, head of product management at Huntsman Security, told CBR:

This may have happened when a click on a link or pop-up triggered the downloading and installation of malicious, secondary, software. As Piers Wilson, head of product management at Huntsman Security, told CBR:

"Sometimes all it takes is for a user to click the wrong link, visit a compromised website, or open a suspect attachment and a new piece of malware that hasn’t yet been covered by AV companies or that uses a zero-day security exploit can get through."

This reiterates the importance of anti-spyware software – these threats from pop-ups are hard to remove so invest in a good product and scan immediately if you see these browser changes.

Toolbar malware


5. Being weird on Twitter?

CBR’s Editor Ellie Burns was alerted to a malware infection when she seemingly sent a message to a friend asking for one million Jamaican dollars for a lucrative business opportunity. No, there is no such opportunity. If your friends are telling you that they have received suspicious social media message or emails, then it’s a pretty sure sign you have malware. However, that is not always the case, as Malwarebytes Chris Boyd told CBR:

"While social media accounts you own posting messages you didn’t write can also be a sign of infection, in many cases that can be as a result of being phished or installing a dubious app — if this happens, be sure to check the permissions in your social media account before panicking, as your PC may not have been compromised in those cases."

If you see this activity, log out of all accounts, choose stronger passwords and, if able, deploy two-factor authentication.


As all security experts will testify to, prevention is the best form of defence. With that in mind, Paul McEvatt, Senior Cyber Threat Intelligence Manager, UK & Ireland at Fujitsu, gave CBR a malware prevention checklist – follow these points and you will be sure to remain malware free!

– Install security software on your device and keep it up-to-date
– Use an adware browser plugins and scan your device on a regularly basis to track cookies or other malware not identified by the firewall software
– Don’t install software/utilities from an unknown source, as those tools may install unwanted software on your device
– Don’t ignore warnings generated by security solutions
– Patch your device
– Ensure your AV is up to date
– Don’t follow links in emails, particularly suspicious ones, always type the URL in a browser
– Don’t click on attachments unless you are sure it is for you
– Enable click-to-play for Adobe Flash or remove it altogether
– Enable two factor authentication on emails
– Add privacy to social media accounts
– Use a client side Virtual Private Network (VPN) such as Freedome
– Never use a free public Wi-Fi

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