Fabian Wosar, security researcher at Emsisoft, created a tool for decrypting files locked by the Gomasom Ransomware. The tool analyzes the encrypted files and allows users to get the decryption key and use it to decrypt their files. The key is always possible to retrieve the key with the tool because victims can take a PNG file encrypted with the ransomware, and compare it to a random PNG file from the Internet. A user guide is available on the website of the security firm.”]
Source: http://securityaffairs.co/wordpress/43074/malware/decrypt-gomasom-ransomware-files.html