Businesses have seen a huge increase in ransomware threats—300% from 2015, according to the FBI, which also reports there were 2,400 ransomware complaints in 2015. In addition to its growing frequency, the means of attack have also improved significantly, as hackers get better at social engineering and at developing malware.

Unlike other types of cyberattack, ransomware attacks are not about extracting data, they are about freezing access, holding businesses functionally hostage, according to Risk Management. When this type of malware infects a system, it encrypts files and documents and demands a ransom, typically in the form of digital currency such as bitcoin, in exchange for a decryption key.

The most frequent targets of attacks, 23%, were government entities, according to Hiscox. The category of business services was second at 18% and finance and insurance institutions followed with 13% of the attacks.

Because the encryption can be crippling and circumventing it is difficult, the FBI advises that businesses may be better off paying the ransom, especially if the company’s system backup has also been infected.