Hello, go to about:preferences by typing it in your URL bar -- on the General tab there will be an entry called Home page, to restore it to your default FIrefox homepage type about:home in that box.

Mkll said

Hello, go to about:preferences by typing it in your URL bar -- on the General tab there will be an entry called Home page, to restore it to your default FIrefox homepage type about:home in that box.

If the problem was so easy resolving, I wouldn't write to support! This is the simplest solution, and I've already tried the hard ones. Of course, I know where to change the start page in preferences. But it doesn't help. The start page is still http://www.apusx.com/

Have you checked about:addons?

Are the settings the way you want them, but the browser goes to another page?

It might be a bad add-on.

There're no add-ons, the browser is clean, I've reinstalled it. Still the same problem.

Site came up clean on VirusTotal: https://www.virustotal.com/#/url/634ea2c367910638811ca14cabbc6b2085aca90bbf17ee94e6a5eb1519c213f2/detection

Your suspicion may be legitimate, as such search-related websites without any additional info are just vague, and I suppose you don’t call it a malware site yourself for nothing.

Google’s Safe Browing check does not report it as one at this point, but that can change rapidly when reports come in. This page mentiones questionable DNS servers, and this page may raise questions too.

I suggest to search the registry for apusx (nothing more) and see if anything is listed on vital locations. Additionally you could run additional malware scanners, so not limited to one, such as the following:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller (for more info, see this alternate TDSSKiller download page)
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Also have a look at the What is search hijacking? support article and the ones mentioned at the bottom.

Personally I would create a new profile and see if that profile’s start page is hijacked from scratch too and if not, use that for the time being. When the issue is resolved, or malware detected in several days when not succeeding right now, you can revert to the current profile.

/Edit: Thinking of what Firefox and Chrome may have in common, it’s worth to check and view the hosts file in C:\Windows\System32\drivers\etc\ for changes. Don’t ask why Edge would not be affected, but that may be set to use a system proxy setting whereas other browsers are not, for instance, or the other way around instead, so check the system proxy setting in Windows too.

Known malware. The Apusx.com browser hijacker is commonly bundled with other free programs that you download off of the Internet.

https://malwaretips.com/blogs/remove-www-apusx-com/

It’s very sad, but many software downloaders/ installers will trick you into installing not only their program, but other programs as well.

You have heard of the fine print in shady contracts, right? Well, some installers you need to look at the itsy bitsy teeny weeny fine print.

You are thinking you are giving the installer permission to install the program you want by using the recommended option. But if you use the Manual Option Instead, you discover all kinds of stuff that you do not even know what it is or what it does.

From now on, everyone needs to Use The Manual Option to put a stop to this.

Note that these programs can also change browser/computer settings.

I've tried all methods mentioned above, including many antivirus/antimalware programms. Nothing helped. I restored the system from back-up, now it's fine. Thank you all for your answers!

That was very good work. Well done.

Make sure you run mal scanners now and then.

FWIW, RegRun Reanimator cleared the problem on my system.