Malicious software, or malware, is a catch-all term for viruses, bugs, trojans, worms and other nasties hackers use to compromise computers. Like a neoplasm, the consequence of an infection depends on the type of malware and how aggressive it is. Malware can wreak destruction on a computer.

Without adequate protection, everyone is at risk. If your computer becomes infected it could be rendered unusable or useless. If it’s on a network, it could compromise other computing systems on that network or any computer through email. This post will define the most common types of malware so should Webroot pick anything up, you can identify what it is and act accordingly.

Adware

Adware is malware that pushes ads onto your computer screen. These usually manifest as pop-up windows in a web browser or on a desktop. Adware by itself is more of an inconvenience than dangerous, but it becomes dangerous when bundled with spyware (see below) which tracks you. The issue with the ads themselves is you never know which are legitimate. They are known to redirect to malicious software, which could be a trojan horse or contain a virus (see below).

Bot

Bots (the malicious ones that is) are hidden software programs that infect and host and connect back to a botnet. A botnet is a network of computers controlled by a hacker. A computer infected by a bot can assist in denial-of-service (DDoS) attacks, send email spam and generate fake internet traffic – all unbeknownst to you. Botnets are even being used to mine Bitcoin and other cryptocurrencies. This malware is dangerous because it exploits the host computer and assists cybercriminals in illegal activity.

Bug

A bug is a flaw in a piece of software which results in an undesirable outcome, like a computer freezing or slowing down. Most bugs are minor flaws that go unnoticed for long periods of time. Others are more sinister and can cause a computer to crash, reboot randomly or freeze for no apparent reason. The most dangerous bug is the security bug, which can be used to bypass user-input security or steal data. Most bugs come packaged in software that has been modified illegally.

Ransomware

Ransomware is a very dangerous type of malware that holds a computer to ransom. It does so by taking control of the computer, usually by locking down the hard drive or encrypting files. It then demands a payment in return for release. The most aggressive ransomware can appear quite threatening. Some ransomware even has a countdown timer, putting pressure on the user to act. Ransomware usually spreads as a result of a dodgy file download but can also be caught through a compromised computer network.

Rootkit

A rootkit is malicious software written with the sole intention to access or control a computer while evading detection from the user and security programs. This can have a devastating consequence, with rootkits known to give hackers full access to a computer. This enables them to remotely execute files, steal personal information, modify the system, alter existing software programs – including anti-malware programs – and add the computer to their botnet (see above). Rootkits are conventionally difficult to identify because they are stealthy. Webroot is one of the best programs at identifying them.

Spyware

Spyware is malware that secretly gathers information from an unsuspecting user by monitoring their computer activity. Spyware can monitor program usage with that data used in combination with adware to deliver relevant ads. It can log keystrokes to identify passwords. It can monitor internet browsing history and collect personal information which can be used to facilitate ransomware. Spyware spreads by way of software vulnerabilities or comes bundled in with a trojan horse (see below).

Trojan horse

A trojan horse is a fake software program pretending to be a legitimate one. Users are tricked into downloading the software because they believe it to be the real thing, only to find the software is malicious. This type of malware is extremely dangerous because it can give a hacker direct access to your computer. The hacker can then remotely steal data, install spyware, modify your files, watch your screen, use your computer in a botnet or send out internet traffic to other websites.

Virus

A virus is malware designed to replicate itself and spread from host to host, often with the end goal of infecting entire computer networks. This type of malware attaches itself to a program. It can lay dormant indefinitely until such a time it is prompted to execute its code. Symptoms can include slow performance, freezes and crashes, suspicious hard drive activity, missing files and strange error messages on screen. Viruses can steal information, destroy files, create botnets, render advertisements and hijack email.

Worm

Like a virus, a computer worm spreads copies of itself from host to host by exploiting network vulnerabilities, but unlike a computer virus, a computer worm does not need to attach itself to any program to execute its code. It can do this by itself. Worms can modify and delete files and deplete computing resources. They can install a backdoor for a hacker to gain control of a computer and inject additional malware such as spyware. Worms are usually transmitted through software vulnerabilities, trojan horses and dodgy downloads.