What to Do If You Find Malware on Your Computer

Finding malware on a computer can be alarming, but the right response can make a big difference. The best course of action depends on the situation, but there are a few practical steps that can help you identify the threat, isolate the device, remove the malware and reduce the risk of it happening again.

Start by understanding how the malware was found

The first step is to work out how the issue was identified in the first place.

1. Endpoint protection or anti-malware software detected it

The most effective way to identify, isolate and help remove malware is to run an up-to-date endpoint protection or anti-malware solution across all devices, including laptops, desktops, servers, tablets and smartphones. These tools are designed to detect malicious files or suspicious behaviour, quarantine threats, and alert the user or administrator so action can be taken.

If your security software has already detected something, that gives you a strong starting point. In many cases, the tool will isolate the file before it can do any further harm.

2. The device is behaving unusually

Another common sign of malware is when a computer suddenly starts behaving differently. For example, a program that normally opens in a few seconds may begin taking much longer, the device may become slow or unresponsive, or applications may crash for no obvious reason.

If this change happens suddenly and persists, even after a reboot, it is worth investigating further.

A few warning signs can include:

• Consistently high memory usage
• Consistently high CPU usage
• Consistently high network activity
• Unfamiliar or suspicious processes
• Repeated pop-ups, redirects or unusual browser behaviour

If you are looking into this manually, tools such as Task Manager, Resource Monitor or system process monitoring tools can help. That said, it is important to understand that not every unfamiliar process is malicious, so caution is needed.

3. Browser pop-ups, redirects or suspicious add-ons

Sometimes the signs are more obvious. You may notice browser redirects, unwanted toolbars, pop-ups or extensions you do not recognise. These can be linked to adware, browser hijackers or other unwanted software.

If that happens, a full anti-malware scan is a sensible first step. You may also need to review browser extensions manually and remove anything suspicious.

4. The device becomes inaccessible

In more serious cases, malware can make a device unusable. This might include ransomware messages, lock-screen alerts, or warnings claiming your files have been encrypted or your device has been blocked.

If that happens, specialist support is usually needed. In some cases, the safest option is to rebuild the system from scratch and restore from clean backups. If ransomware is involved, No More Ransom is a useful resource to check for guidance and available decryptors.

What to do if you suspect malware

If you believe a device may be infected, the first priority is containment.

Step 1: Isolate the device

Disconnect the affected device from the network as soon as possible. That includes:

• Wi-Fi
• Ethernet
• Shared drives
• VPN connections
• Removable media if relevant

This helps reduce the risk of malware spreading, communicating externally, or accessing other systems.

Step 2: Run a full security scan

Use your endpoint protection or anti-malware tool to run a full scan. If the device is part of a wider business network, it may also be worth checking other connected systems for related signs of compromise.

If the scan detects malware, follow the tool’s recommended actions to quarantine and remove it.

Step 3: Review what changed

Try to identify what happened before the issue appeared. For example:

• Was a suspicious email opened?
• Was an unexpected attachment downloaded?
• Was software installed from an untrusted source?
• Did the user click a suspicious link?

Understanding the likely entry point can help prevent the same issue from returning.

Step 4: Escalate if the problem continues

If security scans do not find anything but the issues persist, or if the malware keeps returning, the system may need a deeper investigation. In some cases, wiping the device and reinstalling the operating system is the safest route to ensure nothing remains.

That said, if the original cause is still present, such as a compromised account, unsafe software, or a malicious file stored elsewhere, the infection may return after rebuild unless the root cause is addressed.

Additional checks for more technical users

For more technical readers, there may be value in reviewing:

• Startup items
• Scheduled tasks
• Browser extensions
• Newly installed software
• Unusual login activity
• Firewall or network logs

These checks can sometimes help reveal persistence mechanisms or suspicious traffic, although they can also generate a lot of noise. For many businesses, this is the point where professional support becomes worthwhile.

Prevention is always better than cleanup

The best way to deal with malware is to stop it getting onto the system in the first place.

That means combining technology with user awareness. Good security software matters, but so does user behaviour. Even the best endpoint protection cannot always prevent someone from clicking a malicious link or downloading a dangerous file.

To reduce the risk of malware infections, organisations should consider:

• Using up-to-date endpoint protection across all systems
• Keeping operating systems and software patched
• Limiting admin privileges
• Using strong passwords and multi-factor authentication
• Backing up important data regularly
• Educating users through security awareness training
• Reviewing suspicious emails and links carefully
• Having a response plan in place if something does go wrong

In summary: four simple steps

If you find malware or suspect a device has been infected, focus on four key actions:

1. Identify the threat
Understand how the malware was discovered and what symptoms are present.

2. Isolate the affected system
Disconnect it from the network to reduce further impact.

3. Remove the malware
Use trusted security tools and escalate where necessary.

4. Prevent it from happening again
Address the root cause and strengthen your controls.

If you have any questions or need support responding to malware, get in touch with TechForce Cyber.