Login Items & Extensions- File Open Broker; What is it's purpose?

You can find more details on this in a couple of ways.

First, you can review the items in your LaunchAgents and LaunchDaemons folders. To do this:

1: Activate the Finder

2: From the Go menu, choose Computer. A Finder window should appear containing your Macintosh HD

3: Double-click on Macintosh HD

4: Double-click on Library

5: Inside Library are two folders to investigate: LaunchAgents and LaunchDaemons. Go into each one and look for a file that might be associated to FileOpenBroker. You can select each file and hit the Spacebar to Quicklook them.

Sidenote: LaunchAgents and LaunchDaemons are NORMAL and not all are bad. The simplest explanation is that a LaunchAgents launches a process with a user interface and a LaunchDaemons launches a background process. If we look at a sample file, we can understand the syntax. I have Adobe products installed so I have a com.adobe.acc.installer.v2.plist file in my LaunchDaemons folder. Dropping the header, it looks like this:

<dict>
	<key>Label</key>
	<string>com.adobe.acc.installer.v2</string>
	<key>MachServices</key>
	<dict>
		<key>com.adobe.acc.installer.v2</key>
		<true/>
	</dict>
	<key>Program</key>
	<string>/Library/PrivilegedHelperTools/com.adobe.acc.installer.v2</string>
	<key>ProgramArguments</key>
	<array>
		<string>/Library/PrivilegedHelperTools/com.adobe.acc.installer.v2</string>
	</array>
</dict>

The keys/values of interest are the Program and ProgramArguments keys and their values. In the example above, this tells me what is being launched (/Library/PrivilegedHelperTools/com.adobe.acc.installer.v2). Note, this is an "app" that is running from a place other than the Applications folder.

Inspect each of your files that you find. Find out what "FileOpenBroker" is associated to and what it is launching. If it is something you do not know or understand, share the results with the community. If it is unwanted software, go to the location of the app and delete it. Then remove the LaunchAgent or LaunchDaemon file and reboot your machine to clear the process from RAM.

A second method you can use (if you like Terminal) is to run this command:

sudo sfltool dumpbtm

You must be an admin to run this command and you will be prompted to enter your local password. It is shadowed so trust your typing.

It will spit out a report on all the items in the LaunchAgents and LaunchDaemons folders. For example:

                 UUID: 099A2413-4A74-4AA2-9585-83840A593E10

                 Name: com.adobe.acc.installer.v2

       Developer Name: Adobe Creative Cloud

      Team Identifier: JQ525L2MZD

                 Type: curated legacy daemon (0x90010)

          Disposition: [enabled, allowed, visible, notified] (11)

           Identifier: com.adobe.acc.installer.v2

                  URL: file:///Library/LaunchDaemons/com.adobe.acc.installer.v2.plist

      Executable Path: /Library/PrivilegedHelperTools/com.adobe.acc.installer.v2

           Generation: 8

    Assoc. Bundle IDs: [com.adobe.acc.AdobeCreativeCloud ]

    Parent Identifier: Adobe Creative Cloud

Either way will get you information on what is in the two folders. You may have some left over cruft if you've used migration assistant. Investigate to discover.