Beware the ransom note, a fast-growing hacking form

NEW YORK - It's a chilling moment: A message appears on a computer screen, saying the files are encrypted and the only way to access them is by paying a ransom.

It happened at Jeff Salter's home health-care business in December. The network of nearly 30 computers at Caring Senior Service was infected with ransomware, malicious software that hackers use to try to extort money from people and businesses by preventing them from opening or using documents, pictures, spreadsheets, and other files. If computer users don't pay, there's no way they can access their files.

Ransomware is one of the fastest-growing forms of hacking, cybersecurity experts say. Anyone from a home computer user to a Fortune 500 company can be infected. It can also attack smartphones.

The smaller the users, the more vulnerable they are to losing their files - unless they have a secure backup for their system or go through the complicated process of paying cybercriminals.

Salter thought he was prepared for such an invasion. Most of his files were backed up in a place hackers couldn't access, and he was able to restore his information. But one machine wasn't; it contained marketing materials for his San Antonio, Texas, franchise chain with 55 locations. Salter paid a $500 ransom.

"It would have cost us $50,000 to try to spend the time to recreate the stuff," Salter says.

Like many hackers' tools, ransomware can arrive in e-mails with links or attachments that, when clicked on, unleash software into files. Attacks also can occur when users visit websites. Cybercriminals can attach computer code even to well-known sites operated by tech-savvy companies, said technology consultant Greg Miller of CMIT Solutions of Goshen, N.Y.

Anyone can be hit: individuals, big and small companies, even government agencies.

"We certainly are seeing ransomware as a common threat out there," says FBI Special Agent Thomas Grasso, who is part of the government's efforts to fight malicious software.

Attacks are generally random, but specific companies and people can be targeted. Many small businesses and individuals are at risk because they lack technology teams and sophisticated software to protect them from hackers, said Keith Jarvis, a vice president at Dell SecureWorks, a security arm of the computer maker. Many don't have secure backup systems that will allow them to retrieve uninfected files.

Cyber criminals are starting to target small businesses more than in the past because they're vulnerable, says Liam O'Murchu, a security executive at antivirus software maker Symantec Corp. It works with the government to try to identify hackers.

One way hackers fool small businesses is by attaching realistic-looking invoices to e-mails, O'Murchu says.

A computer user gets a message saying files have been encrypted and is given instructions to pay a ransom, often between $500 and $700. Ransoms must be paid in bitcoins, an online currency. Typically, when the ransom is paid, hackers e-mail a computer code to the user so the files can be released.

If files are backed up securely, users can remove infected files and software from a computer and reset it to what's called factory condition. Files from the backup sites are then restored to the computer.