Am I infected? "adblock shield light" (for Firefox)

[Curt]

Two days ago an extension wanted to install itself on my computer: "adblock shield light 1.3.9" for Firefox. I have Adblock but this was adblock, (not a big 'A'), so I hesitated and went searching for clues on the Internet as to what it was. I've found nothing, but I got curious, so I made a backup and installed it anyway. To my surprise there are no informations about it in Addons; Firefox 42 > Tools > Addons > "More", leads to nothing but the name! I don't understand how it can be version 1.3.9 and be unknown. However, I am not scared (at least not yet), because I have not seen any difference in my computer (32-bits laptop Win 10 Pro)'s performance, and "no malware was found".

But the situation itself keeps nagging me: Where the heck does this little addon come from? Adblock doesn't mention such a thing, and the Internet in general claims it to be unknown! Maybe it has nothing to do with Adblock, and maybe it has. I don't know. Do you? Am I infected? No, of course not.

adblock shield light, anyone? 

[tomos]

It is odd Curt -- this is the only result if I search for "adblock shield light 1.3.9" or "adblock shield".
Dont want to make you paranoid, but I wouldnt be too sure about not having a virus -- or something in that direction.

Might it not be better to just do a system restore and pretend it never happened?
 

[Curt]

no worries, Tom, it was a harmless, very old, adscript for pages - and has gone. But it took me quite a while to understand the language the coder was using. You know, normal English in a foreign way!
 

[f0dder]

I've found nothing, but I got curious, so I made a backup and installed it anyway.

-Curt (November 27, 2015, 06:31 PM)

That's a pretty great way to get your system infected