The word virus is commonly used for any malicious program, but in reality a virus is just one of many kinds. Together they are called malware (malicious software) and each works and harms differently. Let us go through the main types so you know what you are facing and how to defend yourself.

Virus

A classic virus is malicious code that attaches to another program or file and spreads when you run it. Like a biological virus, it multiplies and passes on. It can damage files, slow down the computer or open the door to more malware.

Worm

A worm is similar to a virus, but with one difference: it spreads by itself, without anyone running it. It exploits weaknesses in the network and operating system and can quickly crawl across a whole network. That is exactly why it tends to be very dangerous in company networks.

Trojan

A trojan pretends to be a useful or harmless program, but actually hides malicious code. It does not spread itself, it relies on the user installing it, for example as a fake program or via cracked software. Once run, it can steal data or let in more malware.

Ransomware

One of the most dangerous types. Ransomware encrypts your files and demands a ransom to unlock them. For a company it can mean a complete halt of operations and data loss. How to defend is discussed in a separate article on protecting a company from ransomware.

Spyware

Spyware secretly watches what you do and collects data: visited pages, passwords, card numbers. It runs in the background and the victim usually does not know about it. The goal is the theft of sensitive information.

Keylogger

A specific kind of spyware that records every keystroke. This way it gets passwords, messages and card numbers exactly as you type them. It is among the quietest and most dangerous threats.

Adware

Adware floods the computer with ads, pop-ups and redirects. It tends to be less dangerous than the others, but it slows down the computer, annoys and is sometimes a gateway to worse malware.

Rootkit

A rootkit hides deep in the system, often even below the level of ordinary protection, so the antivirus does not find it. It gives the attacker hidden control over the computer. That is exactly why Secure Boot is useful against it, complicating such burrowing in at startup.

Botnet

A botnet is a network of compromised computers controlled by an attacker. Your computer can be part of it without your knowledge and serve to send spam or for DDoS attacks. Poorly secured IoT devices are often abused for this too.

Scareware

Scareware scares you with a fake warning (“your computer is infected, click here”) to force you to install a malicious program or pay for a useless tool. It builds on fear and a hasty click.

Cryptojacking

Cryptojacking secretly abuses your computer’s power to mine cryptocurrency for the attacker’s benefit. It shows up as slowdown, overheating and higher consumption, although it does not directly steal data.

How to protect against malware

Conclusion

Malware is not one enemy, but a whole family of threats, from viruses and worms through trojans and ransomware to spyware and botnets. Each harms differently, but the defense is common: up-to-date software, caution, an antivirus and backups. When you follow these basics, you are a much harder target.

Suspect an infection or want to protect your company properly? Get in touch, we will clean the computers and set up protection.