Malware & Computer Virus Facts & FAQs | Antivirus

 Whether you’re on a Windows, Apple or Linux computer, a desktop, laptop, smartphone or tablet, you’re vulnerable to ever-evolving cyber threats from computer viruses and other types of malware. The first step to protecting yourself and your data is understanding what you're up against. Here's an overview of the major types of malware, today’s most common computer viruses and their potential impact.

The term "malware" — an amalgamation of malicious and software — is now used to describe any malicious computer program on a computer or mobile device. These programs are installed without the consent of users and can cause several unpleasant effects, including crippling computer performance, mining your system for personally identifiable information (PII) and sensitive data, erasing or encrypting data or even hijacking device operations or computer-controlled hardware. Hackers continuously develop increasingly sophisticated ways to infiltrate user systems. Like a game of whack-a-mole, as soon as one threat is neutralized, a replacement evolves, and the next iteration emerges. Let's look at some of the most common types of malware currently in use.

1. Computer Viruses

What is a computer virus? Computer viruses are a type of malware that earned their name because of how they spread by "infecting" other files on a disk or computer. Viruses then spread to other disk drives and machines when the infected files are received in downloads from websites, email attachments, shared drives or when carried in files on physical media, such as USB drives or—in the early days—floppy disks.

According to the National Institute of Standards and Technology (NIST), the first computer virus, a boot sector virus called "Brain," was developed in 1986. Tired of customers pirating software from their shop, two brothers claim to have designed the virus to infect the boot sector of software thieves' floppy disks. The virus spread through infected copies of the pirated software, jumping from the infected floppy disk to the computer hard drive when the program was booted, or loaded onto the new machine.

2. Worms

Unlike viruses, worms don't require human help to infect, self-replicate or propagate. As soon as they breach a system, they infect their entry point and spread through the device and across any network to which the device connects. By exploiting network vulnerabilities—such as missed operating system (OS) updates or application patches, weak email security or poor internet safety practices—worms can execute, self-replicate and propagate at an almost exponential rate as each new infection repeats the process. Originally, most worms simply "ate" system resources and reduced performance. Now, most worms contain malicious "payloads" designed to steal or delete files upon execution.

3. Adware

One of the most common online nuisances is adware. Adware programs automatically deliver advertisements to host computers. Familiar examples of adware include pop-up ads on web pages and advertising messages that are part of the interface of "free" software. While some adware is relatively harmless, other variants use tracking tools to glean information about your location or browser history. Most of the time, adware collects information to serve better-targeted ads. But sometimes Adware is used for more nefarious purposes including redirecting search results, displaying pop-ups that can’t be closed or link to malware, disabling antivirus software or even going all the way off the rails into the territory of spyware—see #4.

Technically, adware is installed with people's knowledge and consent. But when was the last time you read all the way through a several thousand words "Terms of Service" statement? By clicking the "I Agree" button, you grant consent. Because you have acknowledged and consented to the terms of service, these programs can't be termed malware. Today’s antivirus software typically identifies these programs as "potentially unwanted programs" (PUPs).

4. Spyware

Spyware does just what it says. It spies on what you're doing at your computer. It collects data such as keystrokes, browsing habits, location data and even login information. While adware might include "repurposing" collected data for sale in the terms of service statement, spyware is more duplicitous. Spyware is considered malware because users are unaware of it. The only intent of spyware is malicious. Spyware collects and sells your data to third parties, typically cybercriminals, with no regard for how the data will be used. Spyware may also modify specific security settings on your computer or interfere with network connections.

In another example of how the line between adware and spyware can blur, the rise of mobile computing has seen an explosion of spyware that tracks user behaviour across devices and physical locations without their consent. For example, a free weather app on your smartphone may have gotten your consent to collect and use your location data, ostensibly to provide more accurate forecasts. You agreed to the app’s terms of service which include language enabling to re-use the location as they see fit, so it’s legit. But what happens when that includes selling your location to data to anyone who can afford it, regardless of whether that an online store trying to populate banner ads in your browser or a cybercriminal who cross-references mobile phone user data with other data sources?

5. Ransomware

Ransomware infects your computer, encrypts your PII and other sensitive data such as personal or work documents and then demands a ransom for their release. If you refuse to pay, the data is deleted. Some ransomware variants lock out all access to your computer. Sometimes, they might claim to be the work of legitimate law enforcement agencies and suggest that you've been caught doing something illegal.

6. Bots

Bots are programs designed to automatically carry out specific operations. Although they serve many legitimate purposes, they are also a popular type of malware. Once on a computer, bots can cause the machine to execute specific commands without the user's approval or knowledge. Hackers may also try to infect multiple computers with the same bot to create a "botnet"—short for robot network. These zombie botnets give hackers the ability to remotely manage compromised computers, enabling them to steal sensitive data, spy on user activities, distribute spam automatically or launch devastating Distributed-Denial-of-Service (DDoS) attacks on computer networks and websites.

7. Rootkits

Rootkits allow remote access or control of a computer by a third party. These programs are useful for IT professionals trying to troubleshoot network issues remotely, but they can easily become nefarious. Once installed on your computer, rootkits allow attackers to take complete control of your machine to steal data or install additional malware. Rootkits are designed to go unnoticed and actively hide their presence and that of other malware that they install.

As with most computer viruses and malware, although it’s no guarantee of safety, protecting your devices from rootkits start with keeping current on all OS and application updates and patches to eliminate potential infection routes. Effective detection of rootkits requires real-time monitoring—not just periodic disk drive scans—for unusual behaviour system behaviour.

8. Trojan Horses

Commonly called "Trojans," these programs hide in plain sight by masquerading as legitimate files or software. Once downloaded and installed, Trojans make changes to a computer and carry out malicious activities, without the knowledge or consent of the victim.

9. Bugs

Bugs—flaws in software code—are not a type of malware, they are errors in software code that popular vectors for attackers with malicious intent. Bugs can, on and of themselves, have detrimental effects on your computer, such as freezing, crashing or reducing performance. Security bugs create holes in a computer or network’s defences that are especially attractive to would-be attackers. While better security control on the developer end helps reduce the number of bugs, bugs are another reason why keeping current on software patches and system updates are crucial.