The City of Knoxville is just the latest to learn a single click can have costly consequences.
Hackers took its servers hostage late last week and are still holding them for ransom.
"The FBI recommends not paying that ransom and that's for several reasons," FBI Supervisory Special Agent Jason Jarnigan said. "For one, it encourages the ransomware to continue. There would be no ransomware if people did not pay the ransom."
Jarnigan said the bureau is seeing more ransomware attacks -- and not just on governments or big companies.
Hackers target home computers and cell phones too.
"In fact many computers are infected and you may not even know it," Jarnigan said.
Once ransomware gets in--as Knoxville is learning--it's hard to get it out.
New tech tools only work until hackers learn to beat them. With this in mind, the FBI puts the focus on prevention:
- Make sure your devices are up to date.
- Don't click on emails you don't recognize
- Back up vital information to a cloud-based server or external drive.
"There's a lot of malicious software out there and you may not even know your computer is infected with it," Jarnigan said.
The City of Knoxville said it is now using backup servers. Many city services are still not working right. A spokesperson would not say which ones.