LOS ANGELES -- Americans have been scrambling for weeks to protect their credit reports after Equifax revealed it had been hacked, leaving 143 million vulnerable to identity theft. 

So, what happens if thieves get hold of your personal information? 

IT specialist Art Damaio's nightmare began when a hacker called him after breaking into his personal email.

"He said, 'I am the hacker that's in control of your email right now,'" 37-year-old Damaio told CBS News correspondent Anna Werner. "He said, 'I have all your information,' and I said, 'OK, what's my Social Security?'"

"He started reading it back to be," Damaio said.

"And he was correct?" Werner asked.

"I didn't let him finish," Damaio said.

Damaio hung up, but the high-tech intruder then called again, leaving a voicemail message demanding ransom.

"Hello Mr. Damaio, you will not get your email address back, you will need to contact me and give me the amount of $300 via bitcoin," the message said. "I also have your Social Security number, your driver's license number, front and back. I can basically pretend to be you right now. I am you."

"I was terrified," Damaio said. "Because there's this guy that wants to pretend to be me."

"That made it real," he added.

Next, he started getting text alerts, notifying him in real time as the hacker tried to change his passwords for his eBay profile, his Amazon account, and then his bank account.

"It kind of felt like I was done for," Damaio said. "He pretty much had control of everything I do online."

He doesn't know how his information was stolen, but for criminals, it can be all too easy.

Cybersecurity expert Serhat Atli took Werner on a tour of the "dark web," where criminals sell hacked information like Damaio's.

Continue reading at CBSNews.com.