Ransomware is malicious software, or malware, that blocks access to your computer system and essentially holds your data for ransom. If your credit union's computers fall victim to ransomware, you'l be asked to make an anonymous ransom payment, typically in the form of bitcoins, to an equally anonymous hacker in exchange for removing the ransomware.

There are three levels of ransomware. The least dangerous is called "scareware." In this scenario, fake antivirus software "identifies" a nonexistent virus on your computer and demands that you pay real money for a solution. The typical IT department can easily deal with this type of ransomware.

Ransomware that locks your screen or browser is considered a medium threat. In one popular attack variation, your screen will display a message – allegedly from a government agency like the Department of Justice or the FBI. The message will reveal illegal activity that was conducted on your computer, demanding the immediate payment of some fine.