My housemate has just been internet scammed, is my computer at risk?

[982]

My housemate mistakenly phoned a fraudulent tech support company to fix an issue with his new laptop.
He gave them remote access to his computer to 'fix' the issues and also gave them a card payment over the phone. After this transaction, the phone call disconnected and they have not been in contact since.
Due to all of the security information he handed over to let them have remote access, could they use this to steal information from all devices attached to the same internet network?

[Michael]

The only way your computer is connected to his is that you both probably use the same IP address. Your housemate's computer may now have malware installed on it, or other problems.

As long as your computer hasn't gone through this same, ridiculous process, you should be fine, but your housemate fell for one of the oldest tricks in the book...

[Mark]

Yes. change your passwords, make sure you have decent encryption, and you may need to factory clean all computers connected to the network. Depends on sophistication. Your friend should also cancel his card.

[Jim]

Once in your housemate computer the hacker can reconfigure your router, especially if it has factory default passwords.
Attackers use code to change addresses of your default DNS servers that ISP gives you to addresses of their own servers.
Cyber criminals run their own DNS servers that redirect your router and eventually your computer to phishing or malware sites. When you visit http://www.your-local-bank.net from a computer on your network, you actually visit a fake site and not the legitimate one. etc etc
Change router password & stop remote connection. Then scan or rebuild your computers. By now they've installed God knows what in the computers