Anything found in the Cache is harmless if left untouched as it will be overwritten over time as Cache is used or be deleted if you clear the Cache.

We had an article about this, but is was for old Firefox versions and the steps for clearing the cache are outdated.

• https://support.mozilla.org/en-US/kb/Firefox%20cache%20file%20was%20infected%20with%20a%20virus

"Clear the Cache":

• Settings -> Privacy & Security
  Cookies and Site Data -> Clear Data -> [X] Cached Web Content -> Clear
• https://support.mozilla.org/en-US/kb/how-clear-firefox-cache

Thank you very much,

So basically unless I didn't open it it's probably just a false positive?

I've also cleared my cache and reinstalled Firefox from scratch.

My windows defender just found exactly the same trojan in exactly the same location. Followed the steps above, is anyone able to confirm if this was something that was downloaded as browsing (such as an object on a website) and IS a trojan or if this is just a false positive on the part of windows defender?

My windows defender just found exactly the same trojan in exactly the same location. Followed the steps above, is anyone able to confirm if this was something that was downloaded as browsing (such as an object on a website) and IS a trojan or if this is just a false positive on the part of windows defender?

Hello thank you for sharing the same issue.

I've did some testing and figured out which website was causing it (for me atleast) it was twitch.tv the streaming platform, whenever I visited that website and did a full windows defender scan it detected it. Its most likely a false positive or the website might have been hacked (which i highly doubt) also I would recommend you to run a full windows defender, MSERT, malwarebytes scan just to be sure ur not infected. I avoided the website for now and it hasnt appeared again.