Virus on iMac

I agree with P Phillips assessment that this is a scam - probably one “security” app that you are led to install.

The best way to figure out what is usually by running the diagnostic tool Etrecheck. Its report will tell us about system modifications. You can see tge report for yourself before posting anything here.

If you decide to, click Share Report->Copy Report, then start a reply, click the “additional text” button and paste.

If in fact it is malware what does the user expect will happen if not attend to directly ?

1 - There are no known Windows-like Viruses in the wild that self replicate and affect macOS, because of the underling UNIX  Foundation and Permission Limitation. 

Additionally, and specific to Big Sur macOS 11,  Monterey macOS 12, Ventura macOS 13, the Operating System resides in a Sealed and Read Only Volume that can not be opened by the User and protects against from “ Bad Actor “ Software.

The Only thing this Antivirus software is protecting is the Bank Account of the Developers and for zero return to the User aside from the problems this software creates.

AntiVirus Developers purposefully Market their product to create a “ Fear Factor “. In so doing, creating a False Need for their Product.

The The Built in Security  is all that is required to protect the computer.

There is Adware & Malware which will affect the computer and is generally downloaded from “ Shady “ Websites or Developers who Inject this software into the download.

Should “ Certain & Specific Software “ referenced from above be installed - it will negatively impact macOS. It is suggested, download directly from the Developer , the application Malwarebytes for Mac. 

It is free or paid for added features. 

Run the Application and it should remove the malware / adware. Once done, restart computer and test.

2 - Download the Application Etrecheck directly from the Developer.

This is a Diagnostic Tool that makes no changes to the computer.

It makes a coherent and readable inventory of both the Hardware and Software used on the computer 

The application is free or paid from added features. 

The Report will Not Reveal Any Personal Information. 

Post back the Full Report - copy and paste - >>>> using the Additional Text Icon ( 3rd Icon to last ) <<<<

We can have a look at the report for possible issues and may have possible suggestions to resolve the issues

Agree with @ Luis Sequeira1 on running Downloading the Application Etrecheck directly from the Developer.

This is a Diagnostic Tool that makes no changes to the computer.

It makes a coherent and readable inventory of both the Hardware and Software used on the computer 

The application is free or paid from added features. 

The Report will Not Reveal Any Personal Information. 

This may better identify the culprit application

SCAM attempting to trick the user into purchasing or downloading Malware infected software

As MalwareBytes does Not report any Malware / Adware this tends to make me think there is a Application installed that is the the cause of this issue

Any of the below should be removed as per Developers Instructions 

Any of the below look familiar ?

This will include BitDefender , 

This will included Norton Antivirus , Sophos Av Software

Intego AntiVirus, McAfee, Avast AntiVirus

Ad Guard, Webroot , ESET , Avira

AVG AntiVirus   avira antivirus 

Trustee  

Read some of the posting and arrive at your own conclusions.

The The Built in Security  is all that is required.