Flashback Trojan Malware found by CalmxAV. What should I do Next?

This report is a false-positive which was dealt with back in February.

Go back into ClamXAV and check for updated virus definitions again which should solve the problem.

You can update ClamXAV's virus definitions by clicking the "Update Definitions" button on the toolbar, or by clicking the ClamXAV menu (top left beside the Apple logo) and choosing "Update Virus Definitions".

I would also recommend setting a schedule via ClamXAV's preferences to update virus definitions on a daily basis - be sure to set a time when you know your computer will be running and logged in.

For what it's worth, this was caused by the Firefox developers leaving a setting enabled in one of the files embedded within the Firefox.app itself. The only other time that setting has been seen on Firefox (or Safari) was when the app was infected with the Flashback malware. In this instance, that wasn't the case - just forgetful programmers!

MalwareBytes looks for Mac malware.

ClamXAV also looks for Windows and Mac malware on your Mac (tons more Windows malware).

MalwareBytes focuses on the Mac, which is what you want, rather than a scanner that focuses on Windows.

My understanding about FlashBack is that you were tricked into installing it. So my suggestions are A) just remove Adobe Flash, as most sites have switched to HTML5, B) if you really need Flash, then run Chrome, with its built-in flash, for those sites (I do not suggest running Chrome as it is a resource hog, but if you have one Flash based web site, then run Chrome for that, and then Quit Chrome), C) if you insist on using Chrome ONLY get it from

https://get.adobe.com/flashplayer/

Actually don't even trust me. Got to Adobe.com and get the Flash installer from Adobe.

But realy, just uninstall Flash, you will be safer in the long run.

Download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC and is about the most proven anti-malware software for Mac.

Had you chosen to Open a freshly downloaded file from the secondary file menu, Apple's File quarantine (XProtect) process would have found the FlashBack.A, FlashBack.B, and FlashBack.C malware. The XProtect updates on El Capitan 10.11.6 for March 30, 2018 show these. Malwarebytes should have caught these too.

Yes.

It's not because it is the free trial, it is quick. Did you delete the adware and is your system working as expected now?

Most importantly, Flashback has been extinct since 2012, and there have been no observations of it since the FBI wrested the perpetrators and seized the servers used to distribute and control infections, so unless a user was infected back then or hung onto a Flashback installer from back then, any report of a new infection should be closely looked at before taking any action.

There were at least eight versions of Flashback at the time, so XProtect doesn't provide full protection, but those three caused most of the issues.

I doubt that Malwarebytes would have caught them. I know the developer and he is focused on today's malware for the most part. We are in complete agreement that Flashback is extinct. See his June 3, 2012 Updates at the bottom of http://www.reedcorner.net/about-the-flashback-malware/.