A Beginner’s Guide to Malware

A Beginner’s Guide to Malware

Know the difference between a virus, a worm and a trojan horse? Adware and spyware? Ever heard of a rootkit?

It’s not uncommon to see cyber security issues hit the headlines these days. This year alone, IT problems have wreaked havoc on a number of companies and governments.

To give you a deeper understanding of the types of threat that exist, we’ve created this guide.


Software refers to the various kinds of programs used to operate computers. Malicious software – or malware – are programs specifically designed to do damage to a computer, steal confidential data, undertake unauthorised actions or otherwise disrupt operations. A program counts as malware if it was designed with the intention doing some sort of damage. Programs that do unintentional harm due to some deficiency are not counted as malware.

Malware is commonly spread via malicious email attachments, infected software apps, infected external storage devices and compromised websites.


Adware are programs designed to display adverts on your computer, or to redirect search requests to specific websites. Adware may also collect data without your consent, such as the websites you visit. If you download a free version of a program (freeware), you may be shown ads as a legitimate way for the company that created the program to make money. However, visiting infected websites may also expose you up to other, more annoying forms of adware.


Programs which collect personal data without the owner’s consent are known as spyware. Spyware is often used by advertisers, and so there is a significant overlap between spyware and adware. In addition to browsing habits, spyware can gather information relating to email addresses, passwords and even credit card numbers. Since spyware transmits information back to its creator via the user’s internet connection, the user will experience lower bandwidth.


Ransomware is used by cybercriminals to perform data kidnapping or lock-screen attacks, which prevent users from using their devices until a fee has been paid. Unlike other kinds of attack, the user is notified that their system has been compromised and is given clear instructions about how to recover from the attack, i.e., to pay money to the perpetrator, who will often demand that it be paid in a virtual currency to avoid being tracked.


Computer viruses, like regular viruses, are designed to spread from host to host and have the ability replicate themselves by inserting their own code into the code of other computer programs. In general, viruses are loaded on to your computer without your knowledge or consent. Viruses can delete data, overwrite information, display messages and steal information. With a few exceptions, viruses can only damage the data contained on a computer, not the physical hardware itself.


A special type of virus, worms replicate functional copies of themselves and cause the same types of damage that other viruses do. Unlike other viruses, however, worms do not require the use of a host file to spread. Instead of inserting itself into a file or executable program, a worm will exploit weaknesses in an application or operating system before using a network to replicate itself to other computer systems without human intervention.

Trojan Horse

A trojan horse is any piece of malware that tricks users into installing it by pretending to be a useful piece of software or a legitimate file. Trojan horses are capable of doing many things, from changing your background or desktop icons to deleting files and corrupting information. Trojan horses have also been known to create backdoors that give other users access to your system.

Root Kit.

A root kit is a program designed to give someone continued access to your computer. This allows someone else to use your computer without your knowledge, spy on your actions, execute files, change system configurations and access log files. Like a virus, many rootkits penetrate computer systems by accompanying a trusted piece of software a user wishes to install.

Want to stay protected? Our E-Safety Guide lists some ways you can protect your computer from malware.


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