The Complete Guide to Removing Viruses & Malware from Windows

Malicious software like viruses, spyware, ransomware, and other malware poses severe risks to Windows computers by infecting systems, damaging files, slowing performance, and stealing sensitive user data. Comprehensively removing viruses and malware requires specialized knowledge and proven techniques to isolate, identify, and fully erase infections before they cause further harm.

This in-depth guide will provide readers with expert methodology for detecting, troubleshooting, and completely ridding Windows PCs of viruses, adware, spyware, ransomware, bots, trojans, rogue security software, browser hijackers, and other malware using failsafe removal processes. Follow these best practices to restore infected Windows computers to normal function.

What Are Viruses and Malware?

Malware refers to various forms of malicious software that are intentionally designed to secretly access, damage or infect computers and mobile devices without the user’s consent. Malware comes in many forms, each with unique dangers and challenges when it comes to removal. Gaining a deeper understanding of the most common malware varieties that threaten Windows computers will help inform effective removal strategies.

Computer Viruses

One of the most common and familiar forms of malware are computer viruses. These are programs that spread by inserting copies of themselves into other software applications, critical system files or even the computer’s boot sector. The defining aspect of viruses is this self-replication functionality that enables them to propagate quickly from one system to another via networks, email attachments, infected storage devices and more.

Once a virus has infected a Windows computer, it can exhibit a variety of malicious behaviors such as corrupting, overwriting or even completely deleting important system files and user documents. Some viruses are designed to intentionally damage or disrupt the system in minor ways as a nuisance, while others can render entire operating systems unusable or inaccessible.

Examples of well-known Windows viruses include the Melissa virus from 1999 that spread rapidly via infected Microsoft Word documents sent over email, as well as the infamous ILOVEYOU virus that caused billions in damages by overwriting image, music and data files with copies of itself propogated through email and internet relay chat.

More sophisticated modern virus threats like Conficker and WannaCry have leveraged advanced propagation methods and even weaponized leaked NSA hacking tools to carry out wide-scale infections across the globe.

Spyware

Spyware is a form of malware whose primary function is to collect data and personal information about the user and relay it back to external intruders without the user’s consent or knowledge. Spyware modules are often bundled with free software downloads and then installed silently along with them.

Once active on a Windows computer, spyware can capture a wide range of sensitive user data including browsing history, login credentials stored in the browser, financial account numbers and personal identifying information that is transmitted back to data harvesting botnets or sold to cybercriminals. Some spyware programs even have keylogging functionality to record real-time keystrokes, capturing login passwords and other confidential info.

Because spyware operates covertly in the background gathering data, infections often go unnoticed for long periods while enormous amounts of private information gets exfiltrated. Well-known examples of Windows spyware threats include CoolWebSearch, Zbot, and keyloggers like Hawkeye that targeted banking credentials.

Ransomware

Ransomware is a more modern evolution of malware that, as the name suggests, takes user files ransom by encrypting documents, images, databases and other critical data with strong encryption algorithms. After encryption, ransomware displays demands for payment in cryptocurrency to receive the decryption keys and regain access to the files.

Some of the most damaging and widespread examples of ransomware that have affected Windows users include CryptoLocker, WannaCry, and Sodinokibi. These wield incredibly robust encryption that often leaves no option for decryption besides paying the ransom. Ransomware can be catastrophic for businesses in particular by crippling essential data and documents.

Adware

Adware refers to malware that aggressively displays unwanted advertising content including popups, auto-playing video ads, and obtrusive banner notifications. Much of the adware targeting Windows injects these intrusive ads into web browsers in particular. However, some particularly annoying adware varietals also generate desktop pop-up notifications.

Because adware is focused on generating profits through forced ad views, oftentimes the data of infected users is tracked and sold as well to enable more targeted, personalized advertisements based on browsing habits and usage patterns. Adware strains system resources and can significantly slow down computer performance.

Well-known Windows adware programs include ShopperPro, FairAd and the tax scam malware Genieo which modified search results to advertise fraudulent tax preparation services. Adware in general remains a major threat.

Browser Hijackers

Browser hijackers are an insidious form of malware that as the name implies, hijacks web browser settings like the pre-set homepage, new tab URL, default search engine and bookmarks. Hijackers override these settings to redirect web traffic towards unwanted sites, often pages with further malware downloads or phishing scams.

Since all web activity on an infected machine is essentially redirected, browser hijackers enable cybercriminals to generate fraudulent ad revenue through forced page views or harvest entered data like credit cards and passwords via fake websites.

Some older examples of browser hijackers that plagued Windows browsers like IE and Firefox include e.xploit.in, Bahama Bot and CoolWebSearch. Modern variants continue to evolve related tactics.

Bots

Bots are programs that are covertly installed on victim computers to enlist the machine as part of a broader remote-controlled malware network called a botnet. Botnets can include thousands to millions of compromised computers under the command of a central “bot herder”.

These massive networks are leveraged to conduct all kinds of illicit activity including credential theft, distributed denial of service attacks (DDoS), spreading spam emails, mining cryptocurrency and enabling further malware uploads.

Well-known Windows botnet malware families includeZeroAccess, Kelihos, and Zeus which at its peak in 2010 controlled over 10 million infected machines. Modern bots feature advanced evasion tactics making them particularly challenging malware threats for Windows users.

Rogue Security Software

Also referred to as “scareware”, rogue security software is a highly devious form of social engineering malware that pretends to be legitimate anti-virus or anti-malware security tools. They falsely claim to detect nonexistent infections or performance issues on the victim’s machine in order to pressure the user into purchasing a “full version” of the scam software for removal of the fake issues.

Examples targeting Windows users include Rogue:Win32/FakeRean and Win32:Malware-gen which leveraged convincing interfaces and warnings to trick users into downloading malware under the guise of security software. This remains a persistent scam malware tactic.

Trojans

Trojans, or Trojan horses, are named after the deceptive wooden horse used to infiltrate Troy in ancient times. They similarly appear benign externally but contain hidden malicious functions. Trojans disguise themselves as legitimate software downloads and oftentimes even claim to have useful utilities to entice installation.

However, installed Trojans provide backdoor access to intruders, enabling remote execution of code, control and spying over the infected computer. Well-known Windows trojans include DarkComet RAT used for credential harvesting and Blackhole which installed rootkits for complete system control.

Modern trojans leveraging social engineering via so-called “cracked” versions of legitimate software remain ubiquitous on peer-to-peer sharing networks and torrent sites.

This overview of the most common types of viruses, spyware, adware, ransomware, bots, trojans and other malware provides Windows users key insights into how these attacks function and the dangers they pose. These insights will prove valuable when selecting removal strategies.

Malware Infection Vectors

To effectively prevent future malware infections, users must understand how malicious software initially accesses Windows computers:

Phishing Emails

Malicious email attachments or links that install malware if opened. Social engineering tricks users into enabling the infection.

Infected Websites

Websites hacked to embed malware or exploits in the code, infecting visitors through vulnerabilities in browsers and plugins.

Pirated Software

Peer-to-peer piracy networks and unauthorized download sites frequently contain malware bundled with cracked versions of software.

Contaminated Removable Drives

Malware residing on USB flash drives, external hard drives, and other removable media infects PCs upon connection and autorun.

Software Vulnerabilities

Unresolved flaws and weaknesses in operating systems and applications can enable some forms of malware to slip through and infect the system.

Network Intrusions

Malware worms propogating through networks, weak passwords enabling attacks, and other security holes that facilitate infection.

Social Engineering Manipulation

Tricking users via phone, email, or chat to voluntarily install fake “antivirus” software or remote access tools containing malware.

Staying vigilant against these vectors helps prevent malware from successfully infiltrating Windows computers in the first place. But it’s also crucial to be prepared to remove malware infections.

Signs of Malware Infection on Windows

While advanced malware works unseen in the background, most varieties eventually cause visible issues that indicate infection:

• Degradation in system performance
• Slow boot times
• Programs freezing or crashing frequently
• Unknown processes running in Task Manager
• Mysterious network activity
• Disabled security software and antivirus tools
• Modified, missing, or corrupted files
• Changes to the Windows registry
• New administrator accounts
• Shortcut files appearing on the desktop
• Popups for fake software upgrades or scans

Catching malware early before extensive damage is done requires proactively monitoring for any suspicious changes in system operation and performance. Now let’s dive into the methodology for removing detected malware.

How to Safely Remove Malware on Windows

When viruses, spyware, ransomware, or other malware strikes a Windows PC, swift action is required to eliminate all traces of infection.

• STEP 1: Use Rkill to terminate malicious processes
• STEP 2: Uninstall malicious programs from Windows
• STEP 3: Reset browsers back to default settings
• STEP 4: Use Malwarebytes to remove for Trojans and Unwanted Programs
• STEP 5: Use HitmanPro to remove Rootkits and other Malware
• STEP 6: Use AdwCleaner to remove Malicious Browser Policies and Adware
• STEP 7: Perform a final check with ESET Online Scanner
• STEP 8: Run the System File Checker (SFC) tool
• STEP 9: Run the Disk Check tool

STEP 1: Use Rkill to terminate malicious processes

In this first step, we will download and run Rkill to terminate malicious processes that may be running on your computer.

RKill is a program that was developed at BleepingComputer.com that attempts to terminate known malware processes so that your normal security software can then run and clean your computer of infections. When RKill runs it will kill malware processes and then removes incorrect executable associations and fixes policies that stop us from using certain tools.

1. Download Rkill.

   You can download RKill to your computer from the below link. When at the download page, click on the Download Now button labeled iExplore.exe. We are downloading a renamed version of Rkill (iExplore.exe) because some malware will not allow processes to run unless they have a certain filename.

   

   RKILL DOWNLOAD LINK
   (The above link will open a new page from where you can download Rkill)

2. Run RKill.

   After downloading, double-click the iExplore.exe icon to kill malicious processes. In most cases, downloaded files are saved to the Downloads folder.
   The program may take some time to search for and end various malware programs.

   

   When it is finished, the black window will close automatically and a log file will open. Do not restart your computer. Proceed to the next step in this guide.

STEP 2: Uninstall malicious programs from Windows

In this second step, we will manually check if any unknown or malicious programs are installed on the computer. Sometimes adware and browser hijackers can have a usable Uninstall entry that can be used to remove them.

Now that the malicious programs have been removed from your computer, we can proceed with the next step in this guide.

STEP 3: Reset browsers back to default settings

In this step, we will remove spam notifications,  malicious extensions, and change to default any settings that might have been changed by malware.
Please note that this method will remove all extensions, toolbars, and other customizations but will leave your bookmarks and favorites intact. For each browser that you have installed on your computer, please click on the browsers tab below and follow the displayed steps to reset that browser.

STEP 4: Use Malwarebytes to remove for Trojans and Unwanted Programs

In this next step, we will we will install Malwarebytes to scan and remove any infections, adware, or potentially unwanted programs that may be present on your computer.

Malwarebytes stands out as one of the leading and widely-used anti-malware solutions for Windows, and for good reason. It effectively eradicates various types of malware that other programs often overlook, all at no cost to you. When it comes to disinfecting an infected device, Malwarebytes has consistently been a free and indispensable tool in the battle against malware. We highly recommend it for maintaining a clean and secure system.

1. Download Malwarebytes for Windows

   You can download Malwarebytes by clicking the link below.

   

   MALWAREBYTES FOR WINDOWS DOWNLOAD LINK
   (The above link will open a new page from where you can download Malwarebytes)
2.  

   Install Malwarebytes

   After the download is complete, locate the MBSetup file, typically found in your Downloads folder. Double-click on the MBSetup file to begin the installation of Malwarebytes on your computer. If a User Account Control pop-up appears, click “Yes” to continue the Malwarebytes installation.

   

3. Follow the On-Screen Prompts to Install Malwarebytes

   When the Malwarebytes installation begins, the setup wizard will guide you through the process.

   • You’ll first be prompted to choose the type of computer you’re installing the program on—select either “Personal Computer” or “Work Computer” as appropriate, then click on Next.

     

   • Malwarebytes will now begin the installation process on your device.

     

   • When the Malwarebytes installation is complete, the program will automatically open to the “Welcome to Malwarebytes” screen.

     

   • On the final screen, simply click on the Open Malwarebytes option to start the program.

     

4. Enable “Rootkit scanning”.

   Malwarebytes Anti-Malware will now start, and you will see the main screen as shown below. To maximize Malwarebytes’ ability to detect malware and unwanted programs, we need to enable rootkit scanning. Click on the “Settings” gear icon located on the left of the screen to access the general settings section.

   

   In the settings menu, enable the “Scan for rootkits” option by clicking the toggle switch until it turns blue.

   

   Now that you have enabled rootkit scanning, click on the “Dashboard” button in the left pane to get back to the main screen.

5. Perform a Scan with Malwarebytes.

   To start a scan, click the Scan button. Malwarebytes will automatically update its antivirus database and begin scanning your computer for malicious programs.

   

6. Wait for the Malwarebytes scan to complete.

   Malwarebytes will now scan your computer for browser hijackers and other malicious programs. This process can take a few minutes, so we suggest you do something else and periodically check the status of the scan to see when it is finished.

   

7. Quarantine detected malware

   Once the Malwarebytes scan is complete, it will display a list of detected malware, adware, and potentially unwanted programs. To effectively remove these threats, click the “Quarantine” button.

   

   Malwarebytes will now delete all of the files and registry keys and add them to the program’s quarantine.

   

8. Restart your computer.

   When removing files, Malwarebytes may require a reboot to fully eliminate some threats. If you see a message indicating that a reboot is needed, please allow it. Once your computer has restarted and you are logged back in, you can continue with the remaining steps.

   

STEP 5: Use HitmanPro to remove Rootkits and other Malware

In this fifth step, while the computer is in normal back, we will download and run a scan with HitmanPro to remove Trojans, rootkits, and other malicious programs.

HitmanPro is a second-opinion scanner that takes a unique cloud-based approach to malware scanning. HitmanPro scans the behavior of active files and also files in locations where malware normally resides for suspicious activity. If it finds a suspicious file that’s not already known, HitmanPro sends it to its clouds to be scanned by two of the best antivirus engines today, which are Bitdefender and Kaspersky.

Although HitmanPro is shareware and costs $24.95 for 1 year on 1 PC, there is no limit on scanning. The limitation only kicks in when there is a need to remove or quarantine detected malware by HitmanPro on your system and by then, you can activate the one-time 30-days trial to enable the cleanup.

1. Download HitmanPro.

   You can download HitmanPro by clicking the link below.

   HITMANPRO DOWNLOAD LINK
   (The above link will open a new web page from where you can download HitmanPro)

2. Install HitmanPro.

   When HitmanPro has finished downloading, double-click on “hitmanpro.exe” (for 32-bit versions of Windows) or “hitmanpro_x64.exe” (for 64-bit versions of Windows) to install this program on your computer. In most cases, downloaded files are saved to the Downloads folder.

   

   You may be presented with a User Account Control pop-up asking if you want to allow HitmanPro to make changes to your device. If this happens, you should click “Yes” to continue with the installation.

   

3. Follow the on-screen prompts.

   When HitmanPro starts you will be presented with the start screen as shown below. Click on the “Next” button to perform a system scan.

   

   

4. Wait for the HitmanPro scan to complete.

   HitmanPro will now begin to scan your computer for malicious programs.
   

5. Click on “Next”.

   When HitmanPro has finished the scan, it will display a list of all the malware that it has found. Click on the “Next” button to have HitmanPro remove the detected items.

   

6. Click on “Activate free license”.

   HitmanPro may now require to activate the free 30-days trial to remove the malicious files. To do this, click on the “Activate free license” button to begin the free 30 days trial and remove all the malicious files from your computer.
   

   When the malware removal process is complete, it will display a screen that shows the status of the various programs that were removed. At this screen, you should click on the Next button and then if prompted you should click on the Reboot button. If HitmanPro does not prompt you to reboot, please just click on the Close button.

STEP 6: Use AdwCleaner to remove Malicious Browser Policies and Adware

In this next step, we will use AdwCleaner to remove malicious browser policies and unwanted browser extensions from your computer.

AdwCleaner is a free popular on-demand scanner that can detect and remove malware that even the most well-known anti-virus and anti-malware applications fail to find. This on-demand scanner includes a lot of tools that can be used to fix the side effects of adware. browser hijackers and other malware.

1. Download AdwCleaner.

   You can download AdwCleaner by clicking the link below.

   

   ADWCLEANER DOWNLOAD LINK
   (The above link will open a new web page from where you can download AdwCleaner)

2. Double-click on the setup file.

   Double-click on the file named “adwcleaner_x.x.x.exe” to start AdwCleaner. In most cases, downloaded files are saved to the Downloads folder.
   

   AdwCleaner program will now open and you will be presented with the program’s license agreement. After you read it, click on the I agree button if you wish to continue. If Windows prompts you as to whether or not you wish to run AdwCleaner, please allow it to run.

   

3. Enable “Reset Chrome policies” to remove malicious browser policies.

   When AdwCleaner starts, on the left side of the window, click on “Settings” and then enable “Reset Chrome policies“.

   

4. Click on the “Scan” button.

   On the left side of the AdwCleaner window, click on “Dashboard” and then click “Scan” to perform a computer scan.

   

5. Wait for the AdwCleaner scan to finish.

   AdwCleaner will now scan your computer for malware. This process can take a few minutes.

   

6. Click on “Quarantine” to remove malware.

   When the AdwCleaner scan is completed it will display all of the items it has found. Click on the “Quarantine” button to remove the malicious programs from your computer.

   

7. Click on “Continue” to remove the malicious programs.

   AdwCleaner will now prompt you to save any open files or data as the program will need to close any open programs before it starts to clean. Click on the “Continue” button to finish the removal process.
   

   AdwCleaner will now delete all detected malware from your computer. When the malware removal process is complete, you may be asked to restart your computer.

STEP 7: Perform a final check with ESET Online Scanner

This step involves installing and running a scan with ESET Online Scanner to check for any additional malicious programs that may be installed on the computer..

ESET Online Scanner is a free second-opinion scanner, designed to rescue your computer from malware (viruses, trojans, rootkits, etc.) that have infected your computer despite all the security measures you have taken (such as anti-virus software, firewalls, etc.).

1. Download ESET Online Scanner.

   You can download ESET Online Scanner by clicking the link below.

   

   ESET ONLINE SCANNER DOWNLOAD LINK
   (The above link will open a new web page from where you can download ESET Online Scanner)

2. Double-click on esetonlinescanner.exe to run the installer.

   When ESET Online Scanner has finished downloading, double-click on “esetonlinescanner.exe” to install it program on your computer. In most cases, downloaded files are saved to the Downloads folder.
   

3. Install ESET Online Scanner.

   When ESET Online Scanner starts you will be presented with the start screen as shown below. Select your desired language from the drop-down menu and click Get started.

   

   In the Terms of use screen, click Accept.
   

   Select your preference for the Customer Experience Improvement Program and the Detection feedback system and click Continue.
   

4. Start a Full Scan with ESET Online Scanner

   Click on Full Scan to perform an in-depth inspection of the entire computer.

   

   Select Enable for Detection of Potentially Unwanted Applications, then click Start scan.

   

5. Wait for the ESET Online Scanner scan to finish.

   ESET Online Scanner will now begin to scan your computer for malware. This process can take quite a while, so we suggest you do something else and periodically check on the status of the scan to see when it is finished.

   

6. ESET Online Scanner will automatically remove the malicious files.

   At the end of the scan, the Found and resolved detections screen will be displayed. You can click View detailed results to view specific information. Detected threats are automatically cleaned and quarantined.
   

STEP 8: Run the System File Checker (SFC) tool

In this step, we will use System File Checker (SFC) tool to detect and repair files that may have been corrupted by malware.

The SFC tool scans all protected system files on your computer and replaces any files that are corrupt or damaged with a cached copy that is stored in a compressed folder at %WinDir%\System32\dllcache. By running the SFC tool, you can help ensure that your system is functioning properly and fix any issues.

1. Open Command Prompt as Administrator.

   To open the Command Prompt as an administrator in Windows, type “cmd” in the search bar and then right-click on the Command Prompt result and select “Run as administrator” as shown in the image below.
   
   A User Account Control (UAC) prompt will appear asking for permission to allow the program to run. Click “Yes”.

2. Type “sfc /scannow”.

   You will now be presented with a black screen called the ‘Administrator: Command Prompt’. On this screen, type “sfc /scannow” to scan for and repair any corrupt system files.
   

3. Restart your computer.

   Restart your computer if sfc /scannow repaired files. System File Checker may or may not prompt you to restart but even if it doesn’t, you should restart anyway.

4. Run again sfc /scannow.

   Run again sfc /scannow to check if the files were repaired.

STEP 9: Run the Disk Check tool

As a final step, we will utilize the Disk Check tool, commonly referred to as “chkdsk,” to identify and resolve any issues that were caused by malware.

This tool checks your hard disk for errors and can fix any issues it finds. To use the Disk Check tool, you will need to open the command prompt and enter the “chkdsk” command followed by the drive letter (e.g., “chkdsk C:”). You can also add the “/f” flag to the command to instruct the tool to fix any errors it finds. By running the Disk Check tool, you can help ensure that your hard disk is functioning properly and fix any issues that may be causing high disk usage.”

1. Open Command Prompt as Administrator.

   To open the Command Prompt as an administrator in Windows, type “cmd” in the search bar and then right-click on the Command Prompt result and select “Run as administrator” as shown in the image below. A User Account Control (UAC) prompt will appear asking for permission to allow the program to run. Click “Yes”.

2. Type “chkdsk /f /r”

   You will now be presented with a black screen called the ‘Administrator: Command Prompt’. On this screen, type “chkdsk /f /r” to repair any errors on your hard drive.

3. Restart your computer

   The Disk Check tool may require you to restart your computer in order to complete the scan and repair process. Type “Y” and click on Enter, then restart the computer. A CHKDSK command can take a long time, especially when performed on larger drives. Once it’s done, however, it will present a summary of results including total disk space, byte allocation, and, most importantly, any errors that were found and corrected.

Frequently Asked Questions about Removing Malware from Windows

Here are some of the most frequently asked questions regarding removing viruses, spyware, ransomware, and other malware from Windows PCs and laptops:

What are the signs my Windows computer has malware?

Common infection signs include slowed performance, crashing programs, unknown processes in Task Manager, changed settings, disabled security tools, popups, etc.

How does malware get onto my Windows PC?

Infection vectors include phishing emails, compromised sites, pirated software, vulnerabilities, infected USB drives, and social engineering tricks.

What is the best anti-malware software for Windows?

Top rated options include Malwarebytes Premium, BitDefender Internet Security, and ESET Smart Security.

Does Windows Defender remove all malware?

Windows Defender is decent at stopping some threats, but lacks the robust detection of advanced paid anti-malware tools.

Should I use multiple anti-malware programs together?

Using more than one real-time anti-malware tool is not recommended, but alternate scanners can help remove missed infections.

What risks are there with malware removal tools?

Some free removal tools actually contain malware themselves. Only use trusted options with positive reviews. Avoid unknown software claiming to detect issues.

How can I avoid malware reinfecting my PC after removal?

Practice safe computing habits, avoid suspicious links/attachments, update your operating system and programs, use a firewall and VPN when on public WiFi.

Is completely removing malware possible?

Using the proper technical removal process enables eliminating all traces of malware – but infections can return if you aren’t cautious about prevention.

What should I do if malware keeps coming back?

Persisting malware often indicates a dormant infection or reinfection source. Stick to the proven removal methodology and determine how it is reaccessing your system.

Why is malware removal an essential computer security skill?

Allowing malware infections to persist and accumulate can lead to loss of sensitive data, identity theft, system instability, and even permanent damage. Removing malware keeps Windows PCs performing smoothly and protects your privacy and security.

What precautions should Windows users take to avoid malware?

• Use strong passwords and 2FA authentication
• Maintain comprehensive local and cloud backups
• Don’t open attachments or links from unknown senders
• Only download software from official sources
• Use a modern antivirus program and keep it updated
• Be wary of fake “security alerts” asking you to download software or call tech support numbers
• Regularly update your operating system, browser and other software

Staying informed about malware and following security best practices keeps your Windows PC free of viruses and cyberthreats.

Preventing Malware Reinfection

Removing existing malware is only part of the battle. Users must remain vigilant and take proactive measures to prevent future reinfection:

• Maintain updated antivirus software with real-time scanning enabled
• Avoid clicking links or attachments from suspicious emails
• Only download software from trusted, authorized sources
• Beware phishing attempts and social engineering manipulation
• Enable firewalls and employ a VPN when accessing public WiFi
• Regularly update the Windows operating system and programs
• Exercise caution with removable drives from untrusted sources
• Backup important data routinely
• Disable administrative privileges on user accounts

Combining robust preventive practices with proven malware removal techniques keeps Windows computers clean, secure, and running smoothly. Stay informed on the latest malware threats and removal innovations for maximum Windows PC protection.