The latest malware (malevolent software) is called Petya or Petrwrap. It appears to be a more vicious version of the earlier WannaCry problem that caused so much damage to Windows systems. Petya is expected to be worse.
Both are versions of “ransomware,” products that lock up your files and block you from accessing your own information until you pay a ransom. The thieves then promise to unlock the files and restore your access once you pay the ransom. Unfortunately, experience has shown the thieves often simply take the money and then disappear. The files typically never get unlocked.
Fortunately, there are several methods to restore your files without paying a ransom if, and only if, you are properly prepared in advance of the problem.