False positive?

Hi,

Starting a few hours ago, I began to receive a popup notifying me of a threat. I ran a smart scan and used Malwarebytes, but neither found anything. It’s still popping up once in a while, and seems to only popup when I’m actually using Firefox (hard to say for sure, as the popups are infrequent). I’m currently doing a full scan with Avast, but it’s going to take a long time. I attached an image of the popup; not sure if you need anything else.
Is this a false positive, or should I be worried?

Thanks.

-Gabriel

EDIT:
I should clarify that I noticed it a few hours ago, as that’s when I started using the computer. I have no idea how long it’s actually been going on for.

URL:Mal = Blacklisted URL or IP

Blacklisted for Phishing
https://virustotal.com/en/url/9b5bd4e9de7f8d003c06f595365d8fea5fc0bbe8da4a862f499bb2a897cb9555/analysis/1489677925/

IP history >> https://virustotal.com/en/ip-address/185.53.179.8/information/
Click more button under list(s) for more info, you may need to click several times
Enormus amount of domaines on same IP, and from the names it seems to be just crap

Hi,

Thank you for your response!
Unfortunately I’m really clueless when it comes to these sort of things, but I guess that means it’s some sort of virus or malware, right?
It hasn’t popped up in a few hours now, but I’ve tried scanning it again anyway and it still says that everything’s fine.
If the popup is gone and it says my system is clean, am I good to go?

Sorry for the inconvenience.

you may have some crap in your browser that try to connect to that URL

Try clear all browsers with this >> https://www.malwarebytes.com/adwcleaner/
if still a problem, post back and we will get a malware expert to check some logs from your computer

How did it go?

I think it’s better, thank you! I used CCleaner and I think that helped, but just in case I ran SUPERAntiSpyware and cleaned out the tracking cookies. I haven’t had anything since, so I think the problem was solved.

Thanks again!

CCleaner does not remove malicious files / PUP / Crap
Run the tool i linked to above

Oh, sorry, I forgot to mention that I did that as well.