How to Remove Malware from Company Computers
- Neil Hare-Brown
- May 27
- 3 min read
If you suspect malware is affecting your company’s computers — whether it's strange pop-ups, slow performance, or files behaving oddly — it’s important to act quickly but carefully.
The wrong move can make things worse, while a calm, structured response can stop the spread and limit damage.
This guide outlines how to safely detect and remove malware from company devices — and how to prevent future infections.
Step 1: Isolate Affected Devices Immediately
Start by disconnecting any devices showing suspicious activity from:
The company network (wired and wireless)
VPN or remote access tools
Shared drives or cloud sync tools
This helps contain the infection and prevent it from spreading laterally across your network.
If the device is part of a wider outbreak, consider isolating network segments or shutting down file shares until further investigation.
Step 2: Don’t Delete Files or Run Cleaners Just Yet
Your instinct might be to run a malware remover or delete suspicious files immediately — but don’t rush. You could:
Destroy valuable forensic evidence
Trigger additional payloads or processes
Mask how the malware got in
Instead, take note of:
What the user experienced (error messages, pop-ups, behaviour)
Which files or applications are behaving strangely
When the symptoms started
Take screenshots, collect logs, and prepare to escalate to your IT or incident response provider.
Step 3: Run a Reputable Malware Scanner
Use a recognised endpoint protection or antivirus tool to scan the system. Ideally, this should be done in safe mode or with the device disconnected from the network.
Some reliable tools for business environments include:
Microsoft Defender for Endpoint
Malwarebytes Business
SentinelOne
CrowdStrike Falcon
Sophos Intercept X
Avoid free or untrusted online scanners — they can do more harm than good.
Step 4: Remove Malware or Reimage Safely
If the malware is minor and fully quarantined, follow your antivirus software’s recommendations to remove it. Then:
Reboot the system
Run a second scan to confirm full removal
Review browser extensions, startup apps, and scheduled tasks for leftovers
If the infection is serious or you’re unsure of the integrity of the system:
Wipe and reimage the device from a clean backup
Reset passwords used on or accessed from the device
Review network logs to identify further spread
For critical systems or widespread infections, seek professional support for malware removal and system restoration. STORM Guidance can assist with full malware incident response and secure rebuilds.
Step 5: Check for Lateral Movement
Once the infected device is handled, don’t stop there. Malware often doesn’t work alone — it may have installed backdoors, collected credentials, or moved to other systems.
Investigate for signs of:
New administrator accounts
Unexpected login attempts
Unusual data transfers
Malware present on other machines
Run scans across your network and review firewall, VPN, and endpoint logs for any suspicious activity.
If needed, refer to our page on types of cyber incidents to understand if you’re dealing with a more complex breach.
Step 6: Review Security Gaps
After removal, use the incident as a learning opportunity:
Was the malware delivered via email or browser?
Did users have unnecessary admin privileges?
Were updates or patches missing?
Was MFA enabled?
Address the root cause and harden your defences to prevent a repeat.
Consider running a cyber incident exercising session to test future response readiness.
How STORM Guidance Can Help
STORM Guidance offers professional support for malware response, including:
Endpoint investigation and malware removal
Forensic analysis of infection routes
Full device rebuilds and secure recovery
Threat intelligence and impact assessments
Long-term cybersecurity hardening
We can also provide emergency cyber incident response if the malware incident is ongoing or part of a wider attack.
Don’t Let Malware Sit Undetected
Quick action limits impact — but safe, expert action prevents it happening again.
Whether you’re dealing with an active infection or building your response plan, STORM Guidance can help your business stay secure, resilient, and in control.
