How to Remove Adware, Trojans, Virus & Malware from Windows [Guide]

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 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. Here’s how to remove all malware from Windows:

• 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.

With the malicious programs removed, you’re ready for 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 is one of the most popular and trusted anti-malware tools for Windows — and it’s completely free for removing infections. It catches threats that many antivirus programs miss, including adware, browser hijackers, and trojans. Follow the steps below to scan and clean your PC in just a few minutes.

1. Download Malwarebytes

   Click the button below to download the latest version of Malwarebytes for Windows from the official source. The free version is all you need — it will scan your computer and remove adware, browser hijackers, and other malicious software at no cost.

   

   DOWNLOAD MALWAREBYTES FOR WINDOWS (FREE)
   
   (The link opens in a new page where your download will start)

2. Install Malwarebytes

   When the download finishes, open your Downloads folder and double-click the MBSetup file. If Windows shows a User Account Control pop-up, click “Yes” to allow the installation.

   

3. Follow the On-Screen Prompts to Install Malwarebytes

   The setup wizard will walk you through a few quick screens:

   • Choose where you’re installing the program — “Personal Computer” or “Work Computer” — then click Next.

     

   • Malwarebytes will now install on your device. This usually takes under a minute.

     

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

     

   • On the final screen, click Open Malwarebytes to launch the program.

     

4. Enable “Scan for Rootkits”

   Before scanning, turn on rootkit detection so Malwarebytes can find even the most hidden threats. Click the Settings gear icon on the left side of the screen.

   

   In the settings menu, find “Scan for rootkits” and click the toggle so it turns blue.

   

   Done? Click “Dashboard” in the left pane to return to the main screen.

5. Start the Scan

   Click the blue Scan button. Malwarebytes will automatically update its virus database and start checking your computer for malware.

   

6. Wait for the Scan to Finish

   The scan checks your entire system for browser hijackers and other malicious programs, so it can take several minutes. Feel free to do something else — just check back occasionally to see the progress.

   

7. Quarantine the Detected Threats

   When the scan is done, you’ll see a list of everything Malwarebytes found — malware, adware, and potentially unwanted programs. Click the “Quarantine” button to remove all of them at once.

   

   Malwarebytes will now remove the malicious files and registry entries and move them safely into quarantine.

   

8. Restart Your Computer

   Some threats can only be fully removed after a reboot. If Malwarebytes asks you to restart, click Yes. Once you’re logged back in, your PC is clean and you can continue with the next steps in this guide.

   

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 — it’s designed to catch what your main antivirus might have missed. Instead of relying on a single detection engine, it checks the behavior of files in the locations where malware usually hides. Anything suspicious gets sent to the cloud, where it’s analyzed by two of the best antivirus engines available: Bitdefender and Kaspersky.

Good news: scanning is completely free, with no limits. You only need a license when it’s time to remove what was found — and even then, you can activate a free one-time 30-day trial to clean your PC at no cost. (A full license is $24.95 per year for 1 PC.)

1. Download HitmanPro

   Click the button below to download HitmanPro. Remember — the scan is free, so you have nothing to lose by checking your PC.

   DOWNLOAD HITMANPRO (FREE SCAN)
   (The link opens in a new page where your download will start)

2. Install HitmanPro

   When the download finishes, open your Downloads folder and double-click the file: “hitmanpro.exe” on 32-bit Windows, or “hitmanpro_x64.exe” on 64-bit Windows.

   

   If a User Account Control pop-up asks whether HitmanPro can make changes to your device, click “Yes” to continue.

   

3. Follow the On-Screen Prompts

   On the HitmanPro start screen, click “Next” to begin the system scan. No lengthy setup required — it goes straight to work.

   

   

4. Wait for the Scan to Finish

   HitmanPro will now check your computer for malicious programs. This usually takes just a few minutes thanks to its cloud-based scanning.
   

5. Review the Results and Click “Next”

   When the scan is done, HitmanPro will show you everything it found. Click “Next” to remove the detected threats.

   

6. Click “Activate Free License”

   To remove the malicious files, click the “Activate free license” button. This starts your free 30-day trial — no payment details needed — and unlocks the full cleanup.
   

   When the removal is complete, HitmanPro will show a summary of everything it cleaned. Click Next, then click Reboot if prompted. If there’s no reboot prompt, just click Close — your PC is clean.

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 on-demand scanner that specializes in adware, browser hijackers, and unwanted toolbars — the exact threats that mainstream antivirus programs often miss. It also includes tools that repair the damage malware leaves behind, like hijacked browser settings and malicious policies. It’s a quick scan that’s well worth running.

1. Download AdwCleaner

   Click the button below to download AdwCleaner — it’s free, portable, and requires no installation.

   

   DOWNLOAD ADWCLEANER (FREE)
   (The link opens in a new page where your download will start)

2. Run AdwCleaner

   Open your Downloads folder and double-click the file named “adwcleaner_x.x.x.exe“. There’s no installation — the program starts right away.
   

   If Windows asks whether you want to allow AdwCleaner to run, click “Yes“. When the license agreement appears, click I agree to continue.

   

3. Enable “Reset Chrome policies”

   This setting removes malicious browser policies — a trick malware uses to lock your browser settings so you can’t change them back. Click “Settings” on the left side of the window, then turn on “Reset Chrome policies“.

   

4. Start the Scan

   Click “Dashboard” on the left side of the window, then click the “Scan” button.

   

5. Wait for the Scan to Finish

   AdwCleaner will now check your computer for adware and other malware. This usually takes only a few minutes — it’s one of the fastest scanners around.

   

6. Quarantine the Detected Threats

   When the scan finishes, AdwCleaner will list everything it found. Click the “Quarantine” button to remove all the malicious items at once.

   

7. Click “Continue” to Finish the Cleanup

   Save any open work first — AdwCleaner needs to close your open programs before it can clean. When you’re ready, click the “Continue” button.
   

   AdwCleaner will now delete all detected malware from your computer. If it asks you to restart your PC, allow it — your computer will be clean when you log back in.

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 that performs a deep, full-system check for viruses, trojans, rootkits, and other malware. We use it as the final step because it’s thorough — if anything slipped past the previous scans, ESET will find it. A clean result here means your computer is malware-free.

1. Download ESET Online Scanner

   Click the button below to download ESET Online Scanner.

   

   DOWNLOAD ESET ONLINE SCANNER (FREE)
   (The link opens in a new page where your download will start)

2. Run the Installer

   When the download finishes, open your Downloads folder and double-click “esetonlinescanner.exe“.
   

3. Install ESET Online Scanner

   On the start screen, select your language from the drop-down menu and click Get started.

   

   On the Terms of use screen, click Accept.
   

   Choose your preferences for the Customer Experience Improvement Program and the Detection feedback system (either choice is fine), then click Continue.
   

4. Start a Full Scan

   Click Full Scan — this checks your entire computer, not just the common hiding spots.

   

   Select Enable for Detection of Potentially Unwanted Applications — this lets ESET catch adware and bundled junk programs, not just viruses. Then click Start scan.

   

5. Wait for the Scan to Finish

   ESET will now check every file on your computer. Because it’s a full scan, this can take a while — often an hour or more, depending on how much data you have. Leave it running in the background and check on it from time to time.

   

6. Review the Results

   When the scan completes, the Found and resolved detections screen appears. Any threats found were automatically cleaned and quarantined — there’s nothing extra you need to do. Click View detailed results if you want to see exactly what was removed.
   

   If ESET found nothing — congratulations, your computer has passed the final check and is malware-free.

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.