How to Remove a Virus from an Infected System When Antivirus Fails to Detect It?

1. Disconnect from the Internet

Immediately disconnect the infected device from the internet to prevent the virus from:

• Spreading to other devices on the network.
• Communicating with remote servers to download additional malicious payloads.

2. Boot into Safe Mode

Safe Mode starts your system with minimal drivers and processes, which often disables the virus’s ability to operate.

• Windows:
  1. Restart the computer and press F8 or hold Shift + Restart.
  2. Select “Safe Mode” or “Safe Mode with Networking” (if you need to download tools).
• Mac:
  1. Restart the system and hold the Shift key during boot.

3. Identify Suspicious Processes

Examine running processes to identify unusual activity:

• Windows: Use Task Manager (Ctrl + Shift + Esc) to view processes. Look for high CPU or memory usage by unfamiliar programs.
• Mac: Use Activity Monitor to check for suspicious applications.
• Search for unknown process names online to determine if they are malicious.

4. Manually Delete Suspicious Files

If you locate the malware’s executable file:

• Navigate to its location.
• End the associated process in Task Manager or Activity Monitor.
• Delete the file manually. Be cautious and ensure you’re not deleting critical system files.

5. Run On-Demand Malware Scanners

Specialized malware removal tools are designed to detect and remove threats that traditional antivirus programs might miss. Recommended tools include:

• Microsoft Safety Scanner
• Kaspersky Virus Removal Tool
• ESET Online Scanner

Download the tool using a clean device if necessary and transfer it to the infected system via USB.

6. Clear Temporary Files

Temporary files are a common hiding place for malware. Removing these can aid cleanup and speed up subsequent scans:

• Windows:
  1. Open “Run” (Windows + R) and type %temp%.
  2. Delete all files in the folder.
  3. Use Disk Cleanup to clear additional temporary files.
• Mac:
  1. Open Finder and navigate to ~/Library/Caches.
  2. Delete the contents of the caches folder.

7. Review and Reset System Configurations

Malware often modifies system settings and startup programs:

• Windows: Use msconfig or Task Manager’s Startup tab to review programs that launch at boot.
• Mac: Check Login Items in System Preferences > Users & Groups and remove unauthorized entries.

8. Update Software and Security Patches

Outdated software can be exploited by malware. After cleaning the system:

• Update your operating system to the latest version.
• Install security patches for all applications, including browsers and plugins.

9. Restore System to a Previous Point

If the infection persists:

• Use System Restore (Windows) or Time Machine (Mac) to revert the system to a known clean state.
  • Ensure backups were created before the infection.

10. Seek Professional Assistance

For advanced threats such as rootkits or ransomware, professional help may be required. Cybersecurity specialists can:

• Perform deep scans using advanced tools.
• Manually remove persistent infections.
• Recover encrypted or compromised data.