Authorities warn against 'ransomware' attacks; How can you stay safe?

NEW YORK -- A new digital threat that agencies are warning about comes in the form of an email, an offer or a download, but hiding behind the innocent-looking requests is malicious software. And hackers can use it to hold your personal files hostage.

So how do you protect your computer?

The threatening messages are appearing across the country at an alarming rate. One place hit was a police department in Massachusetts, with the culprits demanding a $500 ransom.

"Our information was held hostage," said Timothy Sheehan, of the Tewksbury PD. "The best option for us, even though it was the worst option for us, was to pay the ransom."

At Intel Security's war room, experts detect more than 13,000 ransomware threats a day across the globe.

"Very often, a user installs ransomware when they get an email from what looks like a company that they would do

business with," CTO Steve Grobman said. "If you were to click on any of the links, it would download and install the ransomware/malware and then encrypt and hold your files for ransom."

Experts say ransomware can also attack your phone.

"We see examples where a user can receive a phishing email on their phone and infect their mobile device," Grobman said. "Your reputation can be held for ransom as well."

One victim received a message demanding a $200 payment to stop false information about child pornography from being sent to his or her colleagues and contacts.

Robert Herjavec, from ABC's "Shark Tank," is a cybersecurity expert and a security partner with Intel. He says ransomware is one of the greatest threats he sees.

"Everybody is vulnerable today," he said.

Still, he urges, don't be powerless.

"Make sure you're backing everything up," he said. "There's so many cloud services today, even on your iPhone, you can back up all your pictures, you can back up all your data. Make sure you're doing that."

He advises unplugging you backup drive so it's out of hackers' reach and always using anti-virus software and a firewall made by reputable companies.

Experts say ransomware criminals are expanding their targets, seeking to take over your smart TV and even your video conference calls. The FBI says if you receive a ransomware popup or message on any of your devices, you should immediately disconnect from the internet and call the police.