Ransomware is a specific type of malicious software that holds a computer and its contents virtually hostage. This malware acts as a means to perpetuate extortion. Attackers who use malware do so with the goal of forcing victims to pay money to regain access to their own files. After the money has been received, the attacker provides the victim with a code that can restore the system back to normal.

Viruses that can encrypt files and withhold them from their rightful owners have also been called cryptoviruses, cryptoworms and cryptotrojans. They have become increasingly popular. Ways that ransomware can infiltrate a computer system are similar to those of the average computer computer worm. Ransomware can enter through an infected email or a network vulnerability. They can also make their way onto the computers of unsuspecting victims by way of search engine activities, infected web advertisements and automatic Internet downloads.

Upon its installation, ransomware can disable or compromise important system functions, such as the computer's startup mechanisms. It will then encrypt the victim's files, making it impossible for the user to access them without undergoing a specific action that can monetarily benefit the attacker. The particular action demanded from the attacker can vary, depending on the attacker's preferences.

For example, a victim of a ransomware attack might be prompted to enter a code into their computer in order to regain access to their files. The code is safely guarded by the attacker, and the attacker will provide it only if the victim sends payment to the attacker. In some cases, the code is not even known by the attacker until payment is sent.

Some attackers urge victims to send short message service (SMS) messages so that victims can be charged for the action. In scenarios such as these, Internet access is also blocked on the victim's computer. Craftier attackers might create a fake malware removal program notice on a victim's computer, alerting him or her of security threats. The notice can warn the victim that the computer's virus protection software has expired and urge him or her to pay for instant removal of the virus from his system.

Computer users can protect themselves against ransomware attacks by installing good antivirus programs on their computers. Being vigilant about web-surfing habits can reduce the risk of computer infection as well. Regularly updating programs to make sure that known security issues have been addressed can also minimize threats.