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What is Malware? | How to Scan, Detect and Remove This Malicious Software?

The common types of malware include ransomware, worms, spyware, Trojan horses which I will discuss in detail in this guide.

They are created by cybercriminals to gain access to someone else’s computer and cause chaos, steal sensitive data, etc.

 You can protect your PC, files, users' account, and other computers on a network from all types of malware by keeping your programs up to date, install good antimalware such as this, using a strong password, avoiding clicking bad links, etc. Read the entire post to learn more (see also how to protect your enterprise in this article).

What is Malware?

This is malicious software or code. It is developed by cybercriminals to access and exploit particular system weak points or damage a computer.

They are also used to steal sensitive data of a user plus other sensitive account information and disrupt computer activities such as internet traffic.

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What is Fileless Malware?

As security measures get better at detecting and blocking both malware and cyber-attacks, cybercriminals continue to develop new techniques to access the operating systems and other PC on the network and evade the detection.

One of the techniques used by cybercriminals today involves the use of fileless malware which has proved to be effective.

Fileless malware refers to a malware program that is running only in memory, so there are no footprints that are left on the endpoint that you can detect with traditional file-based antimalware programs. In addition, see earlier 'What Antivirus Do I Have? article so you don't get caught off-guard.

Types of Fileless Attacks that you are likely to Encounter

  • Registry resident malware- installs itself in the Windows registry (see how remove broken registry items here) and evades detection by not writing any file to a hard drive.
  • Memory only malware-resides only in memory to avoid detection. It comes into your system through a backdoor and it’s considered the most effective.
  • Fileless ransomware-this malicious code is embedded in a document or written into memory using exploits. It also uses legitimate software admin tools to encrypt hostage files without being written to disk (see 'Is AVG Antivirus Safe?').

To stop fileless malware, a company or organization will have to deploy powerful and modern security tools to block security breaches. But first, make sure to go through our 'How does antivirus software work?' post.

The best thing with this kind of malware is that when you reboot your computer, the malware is erased from memory and the attacker will have to start afresh to get their way into your computer system. We have also anwsered a question - Can a Chromebook get a virus?

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What are Different Types of Malware and How To Prevent Them?

The most popular types of malware are Trojans viruses, and, ransomware, spyware, bots, etc.

It is critically important to understand the different types of malware in order to prevent their attacks. That you should install an antivirus software - see 'Lookout vs. AVG' - to further secure your device goes without saying.  Here are types of malware;

  • Ransomware
  • Viruses
  • Bots and botnets
  • Worms
  • Trojan horses
  • Spyware and Keyloggers
  • Rootkits
  • Adware
black hoodie

1. Viruses

This type of malware exists on the internet and often spread when computer users download an infected program. It replicates itself and spread across a computer’s network.

Almost all computer viruses are spread by attaching themselves into executable files, which means the virus can exist on a system and in other PCs on the network but will not terminate until the user opens the infected program.

These computer viruses can delete or corrupt system files and make the computer unusable. They spread quickly when downloading a file online, file-sharing from the network, or email attachments.

Antimalware software uses signature-based detection and behavioral analysis to block a virus. You can also check out the best internet security software, or the best free options we reviewed here. Meanwhile, for Linux users, this post focuses on the best internet protection out there and we also reply to the common question - Does Linux need antivirus software?

2. Trojan Horse

A Trojan type of malware is malicious software that looks legitimate. Often enters the PC and another computer on the networks as a normal or legitimate program and performs malicious tasks as designed by its maker. Before you proceed, make sure to check out our dedicated article about this threat.

Unsuspecting users can be duped into downloading Trojans disguised as legitimate programs and executing them unknowingly.

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Trojans not only allow cybercriminals unauthorized access to end-user devices and access to personal information but also increases security vulnerabilities. It can even download severe malware or act as spyware.

Antimalware programs (see 'AVG vs. Kaspersky' or 'AVG vs. Panda') use heuristic analysis and sandbox technology to detect, analyze and block the Trojan and the files that are already infected with malware.

3. Ransomware

A ransomware malware program will hold your PC hostage by encrypting particular types of personal or confidential computer files; threaten to destroy files and other files on the network and demand ransom or payment to release your computer files.

The strong encryption methods make it impossible to decrypt and stop the threat on the files of PC users without the decryption key. This malware can make your computer unusable until payment is done to get the decryption key.

Cybercriminals demand the ransom payment information of Bitcoin which is untraceable by security agents. To detect this type of malware, antimalware programs use behavioral analysis and sandbox technology to analyze and limit their actions.

bank card

4. Spyware / Keylogger

This is a type of malicious program that secretly collects sensitive data about a user for example bank account details. On the other hand, keyloggers are used to steal passwords and other sensitive information without the user’s knowledge. Look at our earlier post to find out more about this threat.

  • Spyware will actively monitor the actions taken by the user
  • It records your browsing history, search history, and financial details

A keylogger will record a user’s keyboard keystrokes and sends the gathered data to the hackers. If you suspect your PC has this malware, install an antimalware program to filter it. In addition, here's a detailed article on keyloggers.

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5. Worms

Just like viruses, a worm can replicate itself, spreading and infect other computers on the network causing enormous damage by exploiting systems' vulnerability. A worm does not need user action in order to infect computers; instead, it simply replicates itself in systems, as already explained in great details here.

Often, a network worm is designed to overload web servers by consuming bandwidth. They might take time to spread because of their nature of slowing down internet traffic. They exploit computer networks' security failures example being;

  • Outdated operating system
  • Exploiting computers without an antimalware

Antimalware catches the worms using signature-based detection and behavioral-based analysis to detect, analyze and block the worms.

6. Adware

These malicious programs are created to generate unauthorized advertisements on the user’s PC and other PC's on the networks.  You’re most likely to see pop-ups on your browser, get a redirection to advertisements or hyperlinks in unusual places.

antivirus not working

Usually, adware programs record the user's activity and act as spyware as well. These advertisements promote malicious and fraudulent products or services. If you suspect your PC is infected with adware, install an anti-malware program to remove it. And if you are having problems uninstalling existing software, our 'AVG Won’t Uninstall' post will see to it.

7. Bots and Botnet

Bots botnets are created to perform a series of actions automatically. They are used to perform cyber-hacks such as DDoS attacks to gain access and disrupt servers. Read this post to find out how to prevent DDos from damaging your computer.

They are also used for indexing websites for better search results. Anti-malware programs detect this malware by checking computer programs with unusual repetitive actions and blocking their traffic.

8. Rootkits

 These are malicious programs developed to provide unauthorized remote access to a computer without getting detected. Just like trojans, they provide a hacker with admin privileges to alter systems' settings, modify system files and steal data or information.

stealing data

A rootkit is so sneaky that it can manipulate even security software such as an antivirus program that is meant to remove it (see 'AVG vs. AVG Protection' and 'AVG Ultimate vs. Internet Security to learn whether these packages can keep your device safe from this threat). Rootkit attacks could steal user sensitive information or even install another deadly malware program.

It is difficult for traditional antimalware to catch a rootkit because of its intrusive nature. However, patching the security loop-holes and software vulnerabilities with the latest updates will reduce the chances of a rootkit infection. We also strongly recommend reading our reviews such as 'AVG vs. Bitdefender', where we look at advantages and flaws of top antivirus programs (see 'Norton vs AVG, too).

How do Different Types of Malware Enter your Computer?

Over the years, malware programs have become increasingly complex and hard to recover from. For instance, file-less malware can do enormous damage while keeping itself from being sandboxed by your anti-malware program.

It’s therefore important to understand how your devices are infected to prevent further malware attacks.

  • Clicking on questionable links
  • By visiting infected websites
  • Via email attachment or link
  • Through clicking links example being social engineering sites
masked hackers

How to know you have been Hacked?

Here are signs to let you figure out if your devices have malware such as trojans, virus;

  • Your devices loses charge quickly and is even hotter than before
  • Your computer or smartphone is unusually slow
  • You will notice your antimalware software has been disabled and you didn’t do it yourself.
  • New apps or operating systems are being installed on your devices or you have lost data in mysterious ways.
  • You might be getting fake antimalware messages for example “ your computer is hacked, click here to fix it”
  • You get frequent pop-ups with random ads
  • If you start getting redirected to social engineering websites, then your system has been compromised.
  • You might notice new browser toolbars
  • If your friends get social media invites and messages that you didn't send. Fix this by setting two-step verifications.
  • When your mouse moves on its own
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How is Malware used?

Cybercriminals cause malware infections for various reasons such as;

  • Cyber vandalism
  • Espionage
  • Hacktivism
  • Cyberwarfare
  • To steal data

Usually, they are looking to make money. Other times, to test the security of software, protest, or as a weapon of war between governments.

man behind the laptop

How to protect your Computer from common types of Malware?

To protect a system from all types of malware, there’re a few things end users can do;

  • Don’t click on links in emails, they might contain malware. If you recognize the sender, and the URL seems genuine, then you can click on it.
  • Use a strong password. Mix letters with numbers plus special characters. Avoid common passwords such as 1234 and admin.
  • Only buy apps from sources you trust such as the Apple store
  • Update your operating system to patch cybersecurity vulnerabilities
  • Use the best antimalware to prevent malware attacks. The antimalware should also support cloud-based scanning and sandbox features.
About Dusan Stanar

I'm the founder of VSS Monitoring. I have been both writing and working in technology in a number of roles for dozens of years and wanted to bring my experience online to make it publicly available. Visit https://www.vssmonitoring.com/about-us/ to read more about myself and the rest of the team.

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