Protect your company from malware

Goldoson, Chameleon and Rorschach. These are not names of villains in the latest James Bond film, but of malicious software, or malware. Have you suddenly lost files, or is your computer not working at all? Chances are malware is the cause. Find out how to protect your business against it.

Cybercriminals are constantly inventing new ways to spread malware. For example, in early 2023, they exploited the growing interest in AI chatbots, such as ChatGPT. On social media, they spread advertisements with a link to useful software based on ChatGPT. This was in reality malware. So never just click on any link. And take measures to keep malware out.

What is malware?

Malware is the collective name for different types of harmful software. The name is a contraction of the two words 'malicious' and 'software'. Malware can land on all devices with software. Think laptops, tablets and smartphones. An example of malware is spyware that monitors your computer and steals data. Or ransomware that locks your computer until you pay a ransom to criminals. Criminals regularly attack businesses with malware, causing major damage.

Malware often installs itself on your computer without you noticing.

Unnoticed infection

Malware often installs itself on your computer without you noticing it. For example, when you open an infected attachment in an e-mail. Or if you click a malicious link in a message on social media. Malware can also get onto your computer by visiting a malicious website, sometimes even without clicking anything.


Sometimes hackers with malware want to cause as much damage as possible. For example, they might delete your files or shut down your computer network. But often cybercriminals use malware to make money. For example, with ransomware that locks your computer or encrypts your files. The criminals demand that you pay a ransom. Only then will they give you back access to your files. Criminals also use malware to steal your money and data. Or to abuse your computer as part of a botnet to spread spam or malware.

Protect your business

These tips will help you keep malware out.

Secure your devices:

  • Install antivirus software on all your devices. This security software prevents malware infections. And cleans up malware if possible.
  • Install an ad-blocker in your web browser. This ad filter only shows ads on websites you consider trustworthy.
  • Keep all your devices up-to-date and always install security updates right away. Malware often invades your computer through vulnerabilities in outdated software.
  • Make backups regularly. You can then restore files damaged or deleted by malware from a recent backup.

Stay alert:

  • Download and install software only from reliable sources. From well-known software vendors, for example.
  • Only visit websites you trust. From well-known businesses and organisations, for example.
  • Do not just click on a link or an advertisement. For example, in an e-mail you do not trust.
  • Do not just open an attachment of an e-mail or other message you do not trust.

Types of malware

There are several types of malware. Here are the most common ones:


Cybercriminals use ransomware to lock your computer files. You can no longer access or use them. The criminals then threaten to delete your files, unless you pay a ransom. They often demand a ransom in cryptocurrency, like bitcoin.
Ransomware enters your computer when you open a harmful file, for example, an email attachment. Or it comes in through a leak in your firewall, if you have failed to update your security software.

In that case, ransomware enters your computer without you even clicking on anything. Ransomware is also called cryptoware or hostage software.


A computer virus is a dangerous software program that infects your computer. The virus can copy itself onto other files on your computer, and so spread to other computers. This does not happen automatically, you as the user of the infected computer spread the virus. For example, when you email a file you did not know was infected. When the recipient opens the infected file, the virus becomes active on their computer as well. A virus can greatly damage software and files on your computer. It can delete or distribute sensitive information.


A computer worm is a type of malware that infects computers and automatically spreads across your computer network. Unlike a virus, a worm does not have to be installed by a user. The worm uses security leaks and breaches in networks and operating systems to place harmful software. A computer worm usually enters via an email, a harmful link, or a contaminated USB stick.


Adware is a combination of ‘advertising’ and ‘malware’. It displays unsolicited advertisements when you are browsing websites. The most common type of adware is an ad pop-up screen. If you are lucky, adware is simply annoying. But if you are unlucky, you click a harmful adware pop-up, that damages the security settings of your wifi network, for instance. That makes your network vulnerable and allows cybercriminals to break into your computer system.


Spyware is a type of malware that enables cyber criminals to spy on you. They can see exactly what you are doing online, and steal your passwords and bank details to use for fraudulent purposes.

Trojan horse

This type of malware is named after the famous wooden horse used by Greek soldiers to enter Troy and open the city gates from within. A Trojan horse is a harmful software program that appears harmless. It is often sent as an email attachment, or hidden inside programs you download. The harmful program gives a hacker access to your computer. They can edit, copy, or delete hardware data from your computer, without you even noticing.

Remote access Trojan

With a Remote Access Trojan (RAT), a cybercriminal has complete control over your computer. Remotely and without your knowledge. This malware is also called Remote Access Tool or Remote Administration Trojan. This allows the criminal to issue commands to your computer at any time. For example, a command that turns on your webcam and spies on you. Or an instruction with which it transfers your money to its own account.

In the video below (in Dutch), 2 entrepreneurs give tips to protect yourself against malware. 

Recognising an infection

Sometimes it is obvious that your computer is infected with malware. If you suddenly get a message on your screen telling you to pay a ransom after a ransomware attack, for example. But often malware goes unnoticed for a long time.

The following points may indicate a malware infection:

  • Your computer is slower than usual, or programmes don't work as well.
  • Your antivirus software has suddenly turned off automatically and you cannot get it back on.
  • In your web browser, you suddenly see ads, toolbars or plug-ins that were not there before.
  • Your computer has software you did not install yourself.
  • You notice that some files are suddenly missing or you cannot open them.
  • You suddenly get a notification on your screen that all your files have been encrypted. And that you have to pay money to get them back.
  • Your anti-virus software notifies you that there is malware on your computer. Beware: this could also be a fake notification enticing you to download malicious software.

Once malware is on your computer, antivirus software may be able to remove it. If this fails, you may need to restore files from your backup. Also, find out what you can do if a hacker locks your files and demands a ransom.

Read more about what you can do after you have been hacked.