Cyber-thieves are adopting ransomware in "alarming" numbers, say security researchers.
There are now more than 120 separate families of ransomware, said experts studying the malicious software.
Other researchers have seen a 3,500% increase in the criminal use of net infrastructure that helps run ransomware campaigns.
The rise is driven by the money thieves make with ransomware and the increase in kits that help them snare victims.
Ransomware is malicious software that scrambles the data on a victim's PC and then asks for payment before restoring the data to its original state. The costs of unlocking data vary, with individuals typically paying a few hundred pounds and businesses a few thousand.