How can we secure our system from viruses?

Check for latest Service Packs/Updates for Windows, Office,Internet Explorer.

Keep antivirus definitions updated.

Don't click on suspicious pop-up windows.

Don't download or execute applications from untrusted sources.

Delete your temporary Internet files, clean Internet history,and delete Cookies.

Never open email or an email attachment from an unknown source.

Run Malwarebytes at least once a month.