Tips on how to remove malware manually

In this expert response, Nick Lewis explains how to remove malware manually, step by step.

I have had a problem for 2 weeks with an .eml file. It is in multiple folders on my system and I cannot successfully delete them. The file also copies itself onto any attached USB devices. None of my applications are working as a result of this file, what is the best way to rid my machine of this file before it affects others on the network?

First off, remove your computer from the network before the malware potentially copies infected files onto mapped network drives. Whatever malware infected your system, it sounds like it has associated itself with executables on your system and has functionality to prevent it from being removed (which is common). You could potentially restore your computer to a known good restore point. If that doesn't work, you will need to know how to remove the malware manually from your hard drive.

To remove malware manually from a system, follow these basic steps:

  1. On a separate computer, download a malware-removal tool like McAfee Stinger (or another similar tool from a major antivirus vendor) and save it to a USB drive. You may need to use other similar tools depending on the specific malware. Download the installer and updated definition files from whatever antimalware/antivirus software used at your organization.
  2. Boot your computer into safe mode.
  3. Run McAfee Stinger on the infected computer to remove the malware. You may need to use the additional tools that you downloaded earlier if McAfee Stinger didn't remove the malware. If you can't run one of these tools, you'll need to manually fix the file associations. There are some good guides and directions on the Microsoft website; check out these Windows XP malware removal instructions.
  4. After installing or updating the antimalware or antivirus software on the machine, run a full system scan.

To prevent this in the future, be sure the account you normally log in with does not have elevated or administrator-level privileges (savvy hackers can exploit admin-level user accounts quite easily), and always install and update antimalware and antivirus software (if both are not included in your preferred software). If you login with an account with elevated privileges, you may need to contact your IT department to change your account to remove your elevated privileges.

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