If you notice your computer behaving strangely – it’s sluggish, it crashes, or there are some weird pop-ups never leaving you alone – these are the signs that the system might have been infected with an evil software called malware. But why do bad things happen to good computers? Well, malware doesn’t get on your device out of nowhere – it happens to be there because some bad cyberspace guys intended it to do so.
So what is malware?
The word ‘malware’ comes as a combination of ‘malicious’ and ‘software.’ Simply speaking, malware is a destructive code, written with the intent to harm a user’s computer, steal private data, or gain access to the system without the user’s permission.
Common computer malware types
There are various types of malware, and some of them are worse and more damaging than others. Let’s break it down by type and take a closer look at what different kinds of malware do.
Adware is the least dangerous type of malware since it is more oriented to making money than harming a computer system. Adware is an aggressive advertising-supported software developed to display banner advertisements on websites and application windows.
Adware is sneaky: it mostly spreads through automatic downloads that start when visiting a certain website, or it may come bundled with a free version of an app or software with you not even knowing about it. Symptoms alarming about adware residing on your machine include increased CPU usage and annoying banners you keep seeing not only when surfing the web, but in running programs as well.
Just like it says, spyware is made to spy on you. Secretly hiding in the background, it can monitor your computer usage, Internet browsing activity, harvest your personal data, such as passwords, banking details and emails, and even perform keystroke logging or change security settings. All of this gathered information is then sent to a remote user. What is more, once spyware has infected your device, it makes it possible to download and install other malicious applications without your permission.
The way spyware sneaks into a system is mostly through files downloaded from the Internet. Usually, a user doesn’t have a clue when the computer gets infected with spyware – attached to executable files, the malicious program is quietly installed in the background once the file is opened.
Much like a flu virus, a computer virus is a type of malware capable of spreading from host to host and reproducing itself. Attached to files or programs, it can be spread through Internet downloads, email, social media, or text messages. However, a virus cannot infect a computer autonomously – it needs a user to run the program to which it is attached, so that the virus code is executed. The harm caused by a virus ranges from small annoying things, such as desktop wallpaper alterations, to major system crashes and corruption or complete loss of data.
In comparison to viruses, worms look quite innocent, as they do not cause any actual damage to a system. Instead, the only purpose of worms is to make copies of themselves, this way spreading on a local drive or across a network of computers. This self-replicating malware relies on system vulnerabilities, which is completely different from the case of a virus.
In fact, the first known example of malware was a worm dubbed Creeper. Originally, it was created in the 1970s by Bob Thomas, an engineer of a company called BBN Technologies. The experimental computer program was designed to simply hop between mainframe computers. Later, Ray Tomlinson designed an enhanced version of the Creeper – it would not only move between computers but was also capable of copying itself, just like the worms existing in today’s cyberspace.
The Creeper contained nothing malicious. Once a computer got infected with the worm, it displayed a message in the output of a teletype: “I’m the creeper: catch me if you can.” But it was more than four decades ago, and worms spreading today lead to more frustrating outcomes: worms take a lot of space on a hard drive and cause higher CPU consumption levels resulting in a system slowdown.
A trojan malware got its’ name from the classical Greek story about the Trojan Horse. A malicious trojan intends to trick computer users by hiding in innocent-looking programs, such as various applications, games, or even video or music files. Trojans silently run in the background and compromise your security: they are capable of creating backdoors for hackers to get into the system, collecting your sensitive information and even completely locking you out of your computer.
Did you know that trojans attack smartphones as well? Well, they do and in a costly way. Cyber criminals create trojans that automatically send SMS messages to premium numbers, this way making money.
Ransomware has become one of the most serious cyber threats due to its’ ability to spread quickly and the dreadful damage it may cause. Ransomware is designed to make a profit. Spreading of this malicious software relies on exploiting system vulnerabilities. Once the malware infects a machine, it encrypts all the data and makes it no longer accessible to the user. Then, it asks the victim to pay a ransom to get the files decrypted.
Ransomware spreads in the speed of light: if one computer gets infected, the other ones on the network will soon be too. It causes an extremely serious harm when targeting vital services, just like in the case of WannaCry ransomware that attacked medical institutions.
How to protect yourself from malware?
Malware is sneaky, so you should be extremely cautious about your actions online. Here are some tips on how to prevent malware on your machine:
- Avoid opening emails from questionable senders and don’t download any strange attachments or open any links included in a message.
- Always keep your operating system up to date to get the latest security patches.
- Keep a backup copy of your files.
- Use a trustworthy antivirus program.
- Do not download files from untrusted sources.
- If you’re already using NordVPN to protect your privacy and online data, enable the CyberSec feature. This advanced security suite works as a shield against malware by blocking dangerous websites, secures from DDoS (denial-of-service) attacks and gets annoying ads out of your sight.
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