There are plenty of articles offering guidance on preventing or dealing with ransomware, but this one has a good list of decryption tools, so well worth a look.
Ana Dascalesu for Heimdal: Ransomware Decryption Tools – Unlock Your Data for Free
“These free tools will help you decode your data without paying the ransom”
(1) Action Fraud article about DDoS extortion threats by a hacking group: Online extortion demands affecting businesses. Commentary by SC Magazine: Action Fraud warns of new wave of Lizard Squad DDoS attacks
(2) Catalin Cimpanu for Softpedia: Decrypter for Alpha Ransomware Lets Victims Recover Files for Free.
(3) CryptoMix: ransomware that makes the ludicrous claim that the 5 bitcoin ransom will be paid to a children’s charity. Related to CryptoWall 4.0 and CryptXXX: no free decrypter currently available.
Another article from Zeljka Zorz for Help Net Security: A deadly campaign delivers Pony info-stealer followed by Cryptowall ransomware, based on an article from Heimdal Security’s Andra Zaharia. The data stealer Pony is installed on the victim’s PC and forwards credentials to the attackers’ C&C (Command & Control) servers: these username/password combinations are used to compromise legitimate servers by injecting a malicious script, used to send victims to other sites serving the Angler exploit kit (EK). Cryptowall 4.0 is installed on vulnerable systems.
Another article at Heimdal – The Evolution of Ransomware: Is Cryptowall 5.0 Around the Corner? – looks at the ransomware business model and speculates a little on how future versions of Cryptowall might be ‘improved’.