Crypto ransomware is the worst threat at present. There are a lot of variants in crypto ransomware. Only some make it into the limelight, while others fade away.

The reason for a possible increase in the use of crypto ransomware could be because coding crypto ransomware is quite easy compared to other malware. The malware just needs to browse through user directories to find relevant files that are likely to be personal and encrypt them. The malware author need not write complex code, such as writing hooks to steal data. Most crypto ransomwares don't care about hiding in the system, so most do not have rootkit components either. They only need to execute on the system once to encrypt all files. Some crypto ransomwares also check to see whether the system is already infected by other crypto ransomware.

There is a huge list of crypto ransomware. Here are a few of them:

• Locky
• Cerber
• CryptoLocker
• Petya

A detailed analysis of some of these will be covered in later chapters.