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What is a Computer Worm?

A computer worm is a type of malware that propagates itself across a network by replication itself from host to host independently. They often require little or no user interaction to infect a new host nor do they need to write themselves to a particular program or process. Note this is different to a virus which typically requires activation by a trigger on the host or from an external source.

What are the signs of computer worms?

The key signs to try and identify a computer worm on your host include:

  • Checking your speed and performance. As worms try to replicate themselves and spread, they tend to consume some of your host's processing power, if they consume too much whilst the host is busy running over instructions some programs may even crash.

  • Monitoring your storage, as the worm duplicates, it will take up more of the free storage spaces available on the host, including deleting and replacing existing files.

Types of computer worms:

  • Email worms – Email worms spread themselves by sending out infected emails to everybody on the victim's target list. These are often deployed within Phishing campaigns which are designed to entice the user into clicking a malicious link or running an executable.

  • File-Sharing worms – File sharing worms such as the infamous Stuxnet, are designed to spread themselves disguised as media files such as images and videos, with the intention they will be spread through infected storage devices.

  • Crypto/Ransomware worms – Popular versions of these worms include the WannaCry worm that infected millions of devices worldwide, namely the NHS service, with the intention to gain control of the affected host, encrypt its contexts and extort a ransom out of the device owner.

  • Internet worms – These worms spread when the infected host connects to the internet, usually searching for vulnerable web applications and services.

  • Instant Messaging worms – Similar to email worms, internet messaging worms use common messaging platforms to spread across contacts via chat systems.

If you like this blog post, find more content in our Glossary.

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