What is Security Plus?
Security Plus is a free virus, malware scanning service powered by VirusTotal's Public API.
How does Security Plus work?
After installation, a new item will be appended to your context menu whenever a link is selected. By clicking on the item, a bar appears in the page to inform you about the progress of submission of the link to the VirusTotal service. After a while you will get informed about the results of virus scanning.
Note: Please note that the welcome page of the add-on has an embedded Google Analytics script. You may review terms of service here; https://www.google.com/analytics/terms