Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; (<Control> [Mac=<Command>] <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Remove “ Yahoo “ Anything.

Also remove SafeSearch, SearchAssist Incognito, FileConverter Addon, SearchLock, DiscreteSearch, WebSearch, Findwide Search Engine

Now do the same in the computer’s Programs Folder.

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the Applications folder. Linux: Check your user manual.

Hello lounis_hamza,

You seem to have already done just about 'everything in the book', except maybe run different scans as listed here :

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

However, Maktoob.search.yahoo.com doesn't seem to be a malicious program :

See : https://en.wikipedia.org/wiki/Maktoob

And also : https://www.easycounter.com/report/maktoob.search.yahoo.com

I noticed that your system details show these three extensions :

NoRedirect 1.3.2.13.1 and Remove Redirect 2.2.1 and Skip Redirect 2.2.1

Maybe you should try to contact their developers (as you are being redirected ....... )

I think the previous posters are most likely correct that this is caused by one of your extensions, although I couldn't tell you which one. You might disable all of them, restart Firefox, and check again.

If that doesn't help, here are two other things you could check:

(1) Connection Settings

You can check on those here:

• Windows: "3-bar" menu button (or Tools menu) > Options
• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Linux: "3-bar" menu button (or Edit menu) > Preferences
• Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

In the search box at the top of the page, type proxy and Firefox should filter to the "Settings" button, which you can click.

The default of "Use system proxy settings" piggybacks on your Windows/IE "LAN" setting. "Auto-detect" can lead to a flaky connection. You may want to try "No proxy".

Any difference?

(2) Program Folder Infection

Could you check for alien script files in your Firefox program folder? In particular, in these locations (varies for 32-bit / 64-bit):

• C:\Program Files\Mozilla Firefox\defaults\pref
• C:\Program Files (x86)\Mozilla Firefox\defaults\pref

Caution: Do not double-click script files! The default action for a script file it to execute as a Windows system script. (Typically this would just not work, but why risk it.)

Make sure Windows is showing hidden files: https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

A file named channel-prefs.js is normal. Any other file in this folder is suspicious -- for example, dsengine.js (added by Lavasoft/AdAware Web Companion). Remove any such files to a neutral location for further analysis at your leisure.

By the way, your Firefox identified itself as a very old beta version of Firefox 56. If you are not ready for Firefox Quantum, do you want to discuss that, or could you at least update to the last Firefox 56 update (56.0.2 non-beta)?

i uninstall Firefox then reboot

an manually remove

C:\Users\Administrator\AppData\Local\Mozilla

C:\Users\Administrator\AppData\LocalLow\Mozilla

C:\Users\Administrator\AppData\Roaming\Mozilla

C:\Users\Administrator\AppData\Local\Temp

then reinstall Firefox 56.0b9 (i like it for personal reason )

start it

set default search engine an stop update

and reconnect to network

close it

and start Firefox again

check default search engine and "yahoo search engine" still as my default

this is weird

i download it from ftp.mozilla.org

then refresh it again and again and again and again

and i just start to be leave it a programmatic issue because Google chrome is fine (but i like Firefox more)

lounis_hamza said

check default search engine and "yahoo search engine" still as my default

This search engine name (Yahoo Search Engine) is characteristic of a program folder infection caused by the Lavasoft/AdAware program Web Companion. Please see my previous reply for how to check on that.

You may wonder: when you reinstalled Firefox, how can there still be a program folder infection? The reason is that Firefox does not remove the user's script files, it only replaces its own files.

i recheck

C:\Program Files\Mozilla Firefox\defaults\pref

C:\Program Files (x86)\Mozilla Firefox\defaults\pref

then i realized that dsengine.cfg is the problem

i opened it and miss up with the code ( it look like javascript )

and everthing work fine

thank you very much for your help ; )

lounis_hamza said

then reinstall Firefox 56.0b9 (i like it for personal reason ) check default search engine and "yahoo search engine" still as my default this is weird i download it from ftp.mozilla.org

The b9 on 56.0b9 means it is the ninth Beta channel build (there were 13 Beta builds) of Firefox 56.0. If you must use the old vulnerable 56.0 then at least use the Firefox 56.0.2 Release. http://ftp.mozilla.org/pub/firefox/releases/56.0.2/

The Yahoo search engine was recently removed as one of the default search options to use for users of Firefox 52 ESR, 57.0, 58.0, 59.0 later.

I tried everything and nothing worked until I used the Reset Firefox. It was the ONLY thing that worked for me. A bit pissed I didn't try this first. Go to https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings and follow the instructions. That's it. Supper easy!