AVG Signal Blog Security Malware What Is Malware? How Malware Works & How to Remove It
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Malware, a contraction of malicious software, is often created by teams of hackers: usually, they’re just looking to make money, either by spreading the malware themselves or selling it to the highest bidder on the Dark Web. However, there can be other reasons for creating malware too — it can be used as a tool for protest, a way to test security, or even as weapons of war between governments.

But no matter why or how malware comes to be, it’s always bad news when it winds up on your PC. Fortunately, that’s what we’re here to prevent.

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    What does malware do?

    Malware can do all kinds of nefarious things, from stealing sensitive data to destroying entire systems or devices. Malware can crack weak passwords, bore into systems, and spread through networks to more victims. Malware is the force behind most cyberattacks, from data theft leading to identity theft and even large scale data breaches.

    Hackers aim malware attacks against individuals, companies, and even governments. Malware is a broad category, with different forms of malware impacting devices and systems differently. Let’s examine some of the most common forms of malware.

    Types of malware

    Different types of malware are categorized based on how they spread and how they behave. The following is a list of common types of malware, but it's hardly exhaustive:

    • Virus: Like their biological namesakes, viruses attach themselves to clean files and infect other clean files. They can spread uncontrollably, damaging a system’s core functionality and deleting or corrupting files. They usually appear as an executable file (.exe).

    • Trojans: This kind of malware disguises itself as legitimate software, or is hidden in legitimate software that has been tampered with. It tends to act discreetly and create backdoors in your security to let other malware in.

    • Spyware: No surprise here — spyware is malware designed to spy on you. It hides in the background and takes notes on what you do online, including your passwords, credit card numbers, surfing habits, and more.

    • Worms: Worms are a bit different than viruses, because they can spread without a host file. Worms infect entire networks of devices, either local or across the internet, by using network interfaces. They use each consecutively infected machine to infect others.

    • Ransomware: This kind of malware typically locks down your computer and your files, and threatens to erase everything unless you pay a ransom.

    • Adware: Though not always malicious in nature, aggressive advertising software can undermine your security just to serve you ads — which can give other malware an easy way in. Plus, let’s face it: pop-ups are really annoying.

    • Botnets: Botnets are networks of infected computers that are made to work together under the control of an attacker.

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    Specific examples of malware

    Many malware attacks happen silently, with some victims never even realizing they were targeted. But other times, a malware attack is so dangerous and so widespread, it sends shockwaves around the world. Here are some of the most notorious malware examples:

    • The history of malware begins in the 1960s. At that time, hackers created computer viruses mainly for fun, displaying generally harmless messages that then spread to other computers. It wasn’t until the late 1980s that malware turned nasty. The first example of a damaging virus, the Vienna virus, corrupted data and destroyed files. The Vienna virus led to the creation of the world’s first antivirus program.

    • In 2017, WannaCry emerged and quickly became the largest ransomware attack in history. It spread to 150 countries, infecting at a terrifying rate of 10,000 PCs per hour. WannaCry paralyzed governments, hospitals, and universities around the world, causing an estimated $4 billion in damages.

    • Also in 2017, more ransomware attacks, called Petya and NotPetya, splashed onto the scene. These global malware attacks also spread far and wide, with particularly damaging effects in Ukraine, where the national bank was hit. The Petya family of ransomware resulted in around $10 billion in damages worldwide.

    • Hackers pulled off one of the most devastating data breaches in history when they managed to crack Equifax (also in 2017, which was a difficult year for cybersecurity). One of the four major credit reporting bureaus, Equifax keeps highly sensitive data including social security numbers, credit card numbers, loan and debt info, bank account details, birthdays, and more. Hackers were able to access the personal data of 143 million people in the hack. If you’re a US citizen, or have ever worked in the US, you were probably affected by this breach.

    • In 2020, as the COVID-19 pandemic rocked the global landscape, affecting nearly every person and every industry in the world — hackers took notice. Many cybercriminals took advantage of the people’s fear of the novel coronavirus to peddle COVID-19 related phishing scams. From spoofing the World Health Organization to offering fake remote jobs, hackers used fake communications to deploy malware and hijack sensitive personal data to use for identity theft and other purposes. It’s clear that cybercriminals know no bounds when it comes to wreaking digital havoc.

    How to prevent malware

    When it comes to malware, prevention is better than a cure. Fortunately, there are some common sense, easy behaviors that minimize your chances of running into any nasty software.

    • Don’t trust strangers online. Social engineering, which can include strange emails, abrupt alerts, fake profiles, and curiosity-tickling offers, is the most common method of delivering malware. If you don’t know exactly what it is, don’t click on it.

    • Double-check your downloads. From pirating sites to official storefronts, malware is often lurking just around the corner. So before downloading, always double-check that the provider is trustworthy by carefully reading reviews and comments.

    • Get an ad-blocker. Malvertising – where hackers use infected banners or pop-up ads to infect your device – is on the rise. You can’t know which ads are bad: so it’s safer to just block them all with a reliable ad-blocker.

    • Careful where you browse. Malware can be found anywhere, but it’s most common in websites with poor backend security, like small, local websites. If you stick to large, reputable sites, you severely reduce your risk of encountering malware.

    Unfortunately, even if you follow the above advice to the letter, you might still get infected with malware: hackers have found ways to sneak their viruses into every corner of the web. For real security, you need to combine healthy online habits with powerful and reliable anti-malware software, like AVG AntiVirus FREE, which detects and stops malware before it infects your PC, Mac, or mobile device.

    How to detect malware

    Certain strains of malware are easier to detect than others. Some, like ransomware and adware, make their presence known immediately, either by encrypting your files or by streaming endless ads at you. Others, like Trojans and spyware, go out of their way to hide from you as long as possible, meaning they could be on your system a long time before you realize that they’re present. And then there are others, like viruses and worms, that might operate in secret for a time, before the symptoms of their infection start to appear, such as freezing, deleted or replaced files, sudden shutdowns, or a hyperactive processor. 

    Malware-typo

    The only surefire way to detect all malware before it infects your PC, Mac, or mobile is to install a virus scanner and malware removal feature, which will come packaged with detection tools and scans that can catch malware currently on your device, as well as block malware trying to infect it.

    Got malware? Get rid of it

    Each form of malware has its own way of infecting and damaging computers and data, and so each one requires a different malware removal method. To get started, check out our tips for getting rid of viruses and removing malware

    That said, the best way to stay protected or remove an infection is to use anti-malware software, more commonly called an antivirus. The best malware removal tools are included in the most advanced antivirus, and even free ones like AVG AntiVirus FREE have all you need to stay safe from the most common threats.

    Malware on Android

    PCs aren’t the only devices that get malware: any device that can connect to the internet is at risk, and that includes your Android phone. While you might not hear about them as much, Android attacks are on the rise, with phishing websites, fake apps, and unofficial app stores being the main distributors of dangerous software. 

    Android malware, much like PC malware, can do any number of things and cause all kinds of damage. There are viruses, ransomware, botnets, and trojans, spyware, and more: just what you’d expect in this era of smart devices! 

    Fortunately, if a device can be attacked, it can also be secured, and Android phones are no exception. Download a free Android antivirus like AVG AntiVirus for Android to make sure your phone is protected against anything and everything that might threaten it online.

    Malware on Mac

    Macs have a reputation for being virus-proof, and while that was never true, it was true that, for a long time, the amount of malware that could infect a Mac was laughably small. But while the number of threats for Mac are still small when compared to the enormous malware library that attacks PCs, it’s no longer small enough to ignore. There’s a very real threat your Mac could become infected if you’re not careful and if it’s not secured with a powerful, trustworthy antivirus.

    That’s why we recommend you download AVG AntiVirus for Mac to ensure your favorite Apple laptop or desktop isn’t compromised by any malware threats that may be lurking on the web.

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