Western Australia's consumer rights watchdog is warning computer users to be vigilant after a 13-year-old Perth girl was blackmailed by scammers posing as police.
The hackers infected the teenager's computer with a virus, before switching on her web camera remotely and taking a picture of her.
The girl was then sent a message claiming her computer had been frozen by the Australian Federal Police and could only be unlocked by paying a $100 fine.
Dave Hillyard from Consumer Protection says people who receive such messages should stay calm and report it immediately.
"Understand that these guys using these threats, they're a long way away, they don't actually know who you are," he said.
"Whilst they might have a list of your contacts, it's not going to be difficult for us to intercept these kinds of things.
"This young girl did the right thing and told her mum ... it just brings home the scary idea that these guys are hacking into your computer, they're watching you're doing, taking a picture of you, then putting it in a warning."
Mr Hillyard says people should ensure their computer security is up to date and never pay money to scammers.