Security Scan Plus is a virus scanner, only it's limited to active processes & is not a substitute for a proper antivirus and firewall etc. etc..
It is an optional download that you may have overlooked when you install Adobe products (for one example) and can be uninstalled via Control Panel > Programs > Uninstall a Program (Add or Remove Programs in XP).
Moved to General Discussion as a more appropriate spot.
Security Scan Plus carries out some safety checks when it is run. It is primarily intended as a quick check on the current operational status of installed McAfee programs, but it also checks browsing history for recently-visited websites and displays a warning if any of them are listed by SiteAdvisor as potentially unsafe. That is what has happened here. If a user clicks on "Fix Now" ("Jetzt beheben") then the browsing history is cleared and all cookies are deleted (either for the detected site(s) or for all sites). The Help for Security Scan Plus does not say whether the product also checks for any in-memory malware, but I believe it does this also.
I could not cut and paste the text from Help, so I have summarised the information that is displayed in the above screenshot.
Edit - and of course, Security Scan Plus is a marketing tool to sell McAfee products. No doubt about that.
But that means I have to buy the full version? I only get that page if I click on "Fix now"
You don't have to buy anything unless you want to. But Security Scan Plus does not protect you from viruses, trojans, or anything else, at least not in real-time. It is an introduction to anti-virus protection, not the protection itself.
There are free antivirus programs available, if you don't want to pay for full McAfee protection. I believe Microsoft's MSE is quite respected.