Hidden Tear

Hidden Tear is the first open-source ransomware trojan that targets computers running Microsoft Windows^[1] The original sample was posted in August 2015 to GitHub.^[2]

Hidden Tear
Technical name	Ransom.MSIL.Tear
Type	Ransomware
Subtype	Cryptovirus
Classification	Trojan horse
Origin	Istanbul, Turkey
Authors	Utku Sen
Technical details
Platform	Microsoft Windows
Written in	C#

When Hidden Tear is activated, it encrypts certain types of files using a symmetric AES algorithm, then sends the symmetric key to the malware's control servers.^[3] However, as Utku Sen claimed "All my malware codes are backdoored on purpose", Hidden Tear has an encryption backdoor, thus allowing him to crack various samples.^[4]