How does Firefox Sync work because Pref.js or Profile.js was detected as a PUP
Please forgive me its been a year or so this happened. So I was a firefox user and I used firefox sync. One day I downloaded a program that ive used for awhile but turns out I accidently hit express install instead of custom and it installed some crap which made ADW Cleaner or MBAM detect the Pref.js or profile.js as a PUP. It changed my default search engine in firefox. I changed the settings back to my search engine and I removed I think it was a toolbar that was installed. but a day later it was detected as a PUP again and my search engine was changed. Just so happens I needed a reinstall of windows so I did that. But I never reinstalled Firefox :( . Because of the file that was detected as a PUP, does firefox sync the pref.js or profile.js file to all devices? like make a copy put it on all devices so that my history bookmarks ect are on all my devices. I didn't delete my Firefox Sync account so idk why im asking this. I'm just a anxious person with somethings and I don't want what ever this threat was to come back. It was a PUP so idk why im treating this like a Rootkit or Trojan in my mind. I really just want to use Firefox again but im worried this threat would return some how.
Krejt Përgjigjet (1)
Hmm, could there be a monster under the bed? We're here for you. Don't worry.
Regarding Sync, some preferences stored in prefs.js are synchronized and some are not. It's really hard to know what was changed without more information.
Anyway, I'm going to provide a checklist for when you reinstall Firefox, or feel free to start on it now:
(1) Open the Windows Control Panel, Uninstall a Program.
After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it.
Take out as much trash as possible here. If you're not sure, feel free to post program names or a screenshot of the list.
(2) You can search for remaining badware with the scanning/cleaning tools listed in this support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.
(3) Do a Clean Reinstall of Firefox
This takes about 5 minutes. It's not about your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. It's not essential to uninstall Firefox, but you can if you like, saying No to any request about removing personal data.
It only takes a few minutes.
(A) Download a fresh installer for Firefox to a convenient location:
https://www.mozilla.org/firefox/all/
(B) Exit out of Firefox (if applicable).
If you use Microsoft Office, please change your default browser to Internet Explorer temporarily before the next step.
(C) Using Windows Explorer/My Computer (hold down the Windows key and press E to launch it), right-click > rename the program folder as follows (you might have one or both):
C:\Program Files (x86)\Mozilla Firefox =to=> C:\Program Files (x86)\OldFirefox
C:\Program Files\Mozilla Firefox =to=> C:\Program Files\OldFirefox
(D) Run the installer you downloaded in step (A). It should automatically connect to your existing settings.
(4) Remove unwanted or unknown extensions on Firefox's Add-ons page. Either:
- Ctrl+Shift+a (Mac: Command+Shift+a)
- "3-bar" menu button (or Tools menu) > Add-ons
- type or paste about:addons in the address bar and press Enter/Return
In the left column of the Add-ons page, click Extensions.
Then cast a critical eye over the list on the right side. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove).
Hopefully everything will be clean and wonderful going forward, but if you run into problems, please let us know what crept in and that hopefully will allow us to give you more targeted advice and interventions.