From Wikipedia:
The Trojan [FlashBack] targets a Java vulnerability on Mac OS X. The system is
infected after the user is redirected to a compromised bogus site,
where JavaScript code causes an applet containing an exploit to load.
An executable file is saved on the local machine, which is used to
download and run malicious code from a remote location. The malware
also switches between various servers for optimised load balancing.
Each bot is given a unique ID that is sent to the control server.. The
trojan, however, will only infect the user visiting the infected web
page, meaning other users on the computer are not infected unless
their user accounts have been infected separately, this is due to the
UNIX security system.
For a lengthier, more technical description, read this F-Secure article.
Exploits through any other type of file than a .dmg
disk file are rare on macOS. To harm a Mac with any other file type than an application, said file (be it .mp4
, .mp3
, .pdf
, .png
, .jpg
, etc.) would have to exploit a vulnerability in the operating system or media player. If you are using a standard video player (like the latest version of QuickTime) you'll be almost immune to any malware-laced .mp4
files that probably don't exist anyway.
No hacker in their right mind would lace a video file with malware: it's just too hard to get it to work across multiple video players and operating systems, and it's so much easier to get malware on a user's machine using .dmg
files. So I highly doubt a .mp4
file would contain malware that would affect your Mac, which would almost certainly be immune to it anyway with the latest operating system and media player.
So without even answering your follow-up questions yet, you are safe. If you want to feel even safer (and truly ensure that your Mac is unaffected), you can download an antivirus app like Avast or BitDefender as I explain in this answer.
To answer your follow-up questions: if this "video" file was really an application file, your Mac would notify you that it's an application from an unknown developer, force you to go to System Preferences to allow installations of unknown applications, and insist that you type in an administrator's password before allowing this application to run any code.
So even if this was an application file (.dmg
) masquerading as an audio or video file, you'd still be safe. Read more about how you're still safe even if you downloaded a malicious application file (so long as you don't manually install it) in this answer.
tl;dr: you're not going to get malware from downloading a video or audio file.
Edit 1: A notable exception to this "a file can't harm your Mac unless it's an application" rule is the Word .docx
macro. Word documents (and documents for Excel and the rest of Open Office, thanks WGroleau) can try to convince you to run them as a macro, essentially turning them into mini-applications. These can be malware, so never run a downloaded Word document as a macro. Read more about Word macro malware.
Edit 2: Email attachments can look like .mp3
files or .jpg
files, but actually be .dmg
files disguised as such. Whereas when you download a file from the web you'll get a prompt that lets you know what file type you're about to download, you may have no such warning when opening an email attachment. Thus, don't open a suspicious email attachment even if it claims to be a .mp4
/.mp3
/.jpg
/.png
/.pdf
format thinking it's necessarily safe.
Edit 3: If you don't want to install an antivirus app, you can use the website virustotal.com to upload a file and have multiple antivirus engines scan it at once, in the cloud.
Woah, so many edits here.
Best Answer
It is definitely not a part of the standard macOS install.
From the name and the story you're telling, it seems very likely that it is malware!
It might however be from a legitimate piece of software that you have installed. I would try closing the process down, and check the apps you normally use to see if you have any problems. If this is a legitimate piece of software, you should be able to get the process running again by rebooting.
If you did not knowingly install an app that is the "expert search module" - then I would recommend disconnecting the system from the internet, take backups (without deleting older backups) - and if at all possible - reinstall the system from scratch from a known-good backup. If that is not possible, use software such as MalwareBytes to track down the offender and remove it from the system.