Q: Backdoor virus?

Since he gave them remote access to the computer then you must consider all accounts on the computer as compromised. Change all passwords immediately.

Any bank account information should be considered compromised. Call the banks involved and have the card terminated. Request they issue new ones.

If you have a backup created prior to penetration, format the disk, reinstall OS X and restore from the old backup.

That's an outrageous fee considering you can easily do it yourself. All you need to do is reformat the disk and it's the same as a new computer, so you can save that money too.

Start up holding command + option + R. Choose Disk Utility and erase the entire hard drive (uppermost icon). Now, partition your drive, You need to create at least one partition for Mac OS X that should be formatted OS X Extended, GUID partition scheme which is set by default.  Be sure you are connected to the internet via Wi-Fi or ethernet

The original OS that computer shipped with will be installed. After set up, you can upgrade. After it finishes installing, it will reboot and put you SetUp Assistant. Once you set up your accounts, you can log into the AppStore and upgrade OS X to the newest version your Mac meets the system specification for.

Format

How to reinstall OS X - Apple Support

Follow the steps for "Selling or giving away"

Likely the only thing effected is the passwords were made public, and unless software was installed with your consent there is nothing on the computer that wasn't there before. In most cases the remove control software of choice is LogMeIn or TeamVieiwer which are widely available and mostly used by IT pros and amateurs alike for legit purposes and they can easily be removed by following the directions on the developers website. But if you wish to be safe and clean out your system you will need to set aside a few hours of time to perform this, that being said the process is quite easy and has very few steps:

first backup your computer

Use Time Machine to back up or restore your Mac - Apple Support

then use MacJacks recommendation to recover the OS from Apple and start fresh.

Use the migration assistant to restore (from your time machine backup) your account data which is your music, mail, documents and pictures but you may wish to keep the applications out of the restore and anything you need outside of Apple provided software you should use the original installers or ones from the developers websites.

reset your router if you feel compelled, but IMHO that reeks of a scare tactic by the tech you called. I would honestly not recommend his business to anyone after that ludicrous quote. Your computer repair tech is providing you with a disservice and asking for an astronomical fee to facilitate it.

Recommended settings for Wi-Fi routers and access points - Apple Support

Go for it, it's easier than you think. If you have questions along the way post back.

mthanlon wrote:

 

... I called a local computer repair. He gave me an estimate of almost $1,000 to back up and restore my files. Erase the operating system and reinstall it, scrub the computer, etc. He also wants to come out to my house to scrub my router.

You should put that local computer repair shop on your "never call" list. That fee is so outrageously expensive that I wonder if they're the ones who perpetrated the scam to begin with. To "scrub" your router makes no sense. Never, ever, consider using that company's services for anything. Trash removal, maybe.

Even if you needed to contact Apple for assistance with this problem (which you don't) their one-time incident support fee is $29.

Unfortunately, these scams have become very common. It's very disheartening to hear when someone is exploited by them. Please read Phony "tech support" / "ransomware" popups and web pages.

Never let anyone log in and use your Mac, either in person or through remote access. The same goes for your home computer network.