Hi, that sounds very suspicious - don't install it!

If you are in any doubt about the authenticity of update pop-ups etc., it's best to ignore them and check for yourself by opening the 3-bar menu > Help (question mark at bottom right) > About Firefox.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

. Whenever you get a message / popup that software / files need to be updated;

DO NOT USE ANY OF THE PROVIDED LINKS

While this may be a legitimate message, it could also be Malware or a Virus. Any time you want or need to check for upgrades, go to the web site of the True Owner of the program in question. For example, to check out Firefox, go to Mozilla.org. {web link}

You can also report such a site at; Google Report Phishing Page {web link} which is the same when done while on site by going to Help > Report Web Forgery

Help us safeguard Mozilla’s trademarks by reporting misuse {web link}

Firefox updates are never done by way of a .exe

Firefox is not just for Windows as it is for Mac OSX and Linux also so updates are done either in Firefox itself (with a .mar file) or by download from mozilla.org

You already have Firefox 42.0 which is the current Release which was released on Nov 3rd.

Timely advice from three Mozilla experts; all confirmed this was not something to install as Mozilla would not use an .exe file as an update or problem fix. I am a bit wiser now thanks to the three mozilla-kateers ...

I was just prompted to install this from a website "phaccounty-taxes.net" . The file installs Cryptolocker, under no circumstances should you install this file. It is the Cryptolocker trojan. What is worse is all I did was open a new tab in FireFox. I did not click on anything, no email, new tabs are set to blank. Two other of my computers on different networks were infected by Cryptolocker and we could not find the source as browsing history showed no ad clicks or out of the ordinary site visits, and no email attachments were opened. Apparently when FireFox is opened and goes to check for updates it is hijacked and you are redirected to a false website to install the Patch. This means there is a security hole in FireFox. Cryptolocker is a terrible trojan it encrypts all your data files and holds your files ransom for $500.00. If you do not pay your files are unrecoverable. FireFox please fix this!

You need to get Cryptolocker uninstalled on your Windows since you ran that Fake Firefox patch .exe file.

https://malwaretips.com/blogs/remove-cryptolocker-virus/

Hi, I found more info on this FirefoxPatch.exe malware. I posted the info on another similar Mozilla support thread: https://support.mozilla.org/en-US/que.../1092584#answer-818322.

The source of how the user is re-directed to the fake Firefox Update Center website is actually from the website that the user was browsing on. It is called "malvertising" and even browsing on legitimate websites can re-direct the user's browsers to a malware webpage. So, please don't download files before researching carefully if it's legitimate first and warn others! Thank you.

Btw, the malware website that I got redirected to was "thitueasyexport.net".

I'm attaching an image of a bogus Firefox Security Warning I was redirected to on December 9. Here's a virustotal analysis of the 288 KB download (I had earlier seen a 348 KB version): virustotal firefoxpatch . And here's a virustotal analysis of the download URL: virustotal phaccounty-taxes .

Multiple security products have now detected no threats on my PC. The best defense appears to be ad-blocking browser add-ons. I haven't seen any more redirects even from reported malvertising websites since installing Adblock Plus and unchecking "allow some non-intrusive advertising." (Certain ads at one website were apparently of the "non-intrusive malvertising" variety.)