Ransomware is a type of malware that prevents or limits users from accessing their system. This type of malware forces its victims to pay a ransom in order to regain access to their computers, or to get their data back. Some ransomware encrypts files (Cryptolocker), while others block communications (CTB Locker). It is estimated that these types of malicious program have procured an estimated $3 million and $18 million by June of 2015, respectively.

Ransomware is considered a "scareware" because it intimidates users into paying a ransom. The ransom prices vary, ranging anywhere from $24 to more than $600, sometimes requiring a bitcoin equivalent. However, sometimes the system lockdown is not restored even following payment.

The first cases of ransomware infection were in Russia in 2005 and 2006, and the infection was limited to Russia for quite some time. However, the lucrativeness of the malware for its creators caused it to spread, and by 2012 it has made its way across Europe, Canada, and the US. By 2013, variants of ransomware were developed that encrypted files. In June of the same year, data was released showing that over 250,000 unique ransomware programs had been isolated from January to March, alone.

These malware can be encountered through email and email attachments, or by visiting websites. Upon execution of the program, ransomware either shows a full-screen image or notification, or locks system files. Victims of this infection are given instructions on how to pay their ransom.

These ransomware programs are a very real and growing threat. If you encounter an infection, immediately disable system restore, and run a malware scan to detect and delete the files.