Paranoid Mother Worrying about Hackers, Need EXPERT (MAC)

[thomasthomashomework]

Hello, I was hoping an expert could help me answer these questions...
Just a brief introduction to my dilemma. I want to create a cod4 server and an internet friend (not that trustworthy) is helping me via teamviewer. I am using mac OSX Mavericks. I have my firewall enabled and I have avast! installed. He is making the server through ubuntu 12.04 virtual machine called parallels.

The following question applies to when a hacker already has full control of your computer (aka my friend setting up my cod4 server),
What is the worst that can happen? Hack my bank account? Remote access to my computer whenever he wants? Hack other computers in my house and hack their bank account? Hack my ip? Hack my wifi?!?

My mom is quite worried about teamviewer and I need some hard evidence on what hackers can do. She at the moment believes that hackers have the power to hack my mac, hack the wifi network then hack her pc and hack her bank accounts. Is this possible?

[matt]

What is the worst that can happen? Hack my bank account? Remote access to my computer whenever he wants? Hack other computers in my house and hack their bank account? Hack my ip? Hack my wifi?!?

Yes all of this is possible to someone who has FULL access to your computer.

Is this the worst that can happen?
Hell no. It can get much much worse than that.

This Internet random person, could be stealing your identity, performing crimes in your name with a view to you going to jail.
They could be stalking your house, with a view to kidnapping your sister for nefarious means.
They could watch you mum get dressed / undressed from the webcam on her laptop in her room

There really isn't much that a random person with ulterior motives couldn't achieve if they really wanted.

Give up COD, take up sport. Much better for you.

Matt
(Paranoid Dad of four)