400 Bad Request Base decode server error http referer

I’m afraid that you have fallen victim to the base64 injection hack affecting all PHP files (not just WordPress) on some shared hosting providers. Remain calm and carefully follow this guide:

https://codex.www.ads-software.com/FAQ_My_site_was_hacked

Thanks for the reply. I thought it was something minor. From your response, and the FAQ, this seems to be major.

I’ve read the guide, but I’m a little bit confused. I’m trying to understand the bigger picture. Is this malicious code something that I am supposed to find?

If I’m not mistaken, according to the guide, I am supposed to back up everything and then replace all the files in my current theme and also replace all the files in my current “hacked” wordpress installation?

How long should a process like this take? I might have to hire someone. This sounds like it’s beyond what I can do without mucking things up. ??

Is this malicious code something that I am supposed to find?

Yes, it’s been inserted into several files.

I am supposed to back up everything and then replace all the files in my current theme and also replace all the files in my current “hacked” wordpress installation?

Yes, backup everything, then replace as many files as possible with original downloads (that will leave less files to “clean” later).

How long should a process like this take?

Maybe about an hour? Just follow the guide carefully. It’s pretty detailed. As long as you’ve made a backup, you can always start over if you mess something up.