This tool is able to find encrypting key that virus maintained in PC memory.
https://github.com/gentilkiwi/wanakiwi/releases
More details about Wannycry can be found reviewing following article:
http://www.alessandromazzanti.com/2017/05/hacker-emergency-patch-kb4012598.html
[update 2017.06.11]
1) Considering that wanncry encrypt files and delete originals here it is recovery free tool:
https://www.easeus.com/data-recovery/recover-decrypt-wannacrypt-encrypted-files.html
2) Downloading and Using the Trend Micro Ransomware File Decryptor
Download Link
3) Welcome to No Ransom, the place to find the latest decryptors, ransomware removal tools, and information on ransomware protection.
What is ransomware? It’s a malware (a Trojan or another type of virus) that locks your device or encrypts your files, and then tells you that you have to pay ransom to get your data back. It’s not cheap, and there’s no guarantee of success. If you become a victim of ransomware, try our free decryption tools and get your digital life back.
https://noransom.kaspersky.com/
[update 2017.08.16]
new link:
https://www.microsoft.com/it-it/download/malicious-software-removal-tool-details.aspx
About some tools I would suggest these:
Malwarebytes and Bitdefender.
Here they are some free MAC Antivirus:
About Wannacry and similar ramsoware you can review this blog article, consider these toos to:
Antivirus - WannaCry Free Decryptor tool
Hacker - MS17-010 patch KB4012598 against Wannacry Ramsoware
- Vaccinator.
- immunizer against Petya and other ransomware.
Some precedently information was taken reviewing this interesting article: