The Stegoloader malware family (also known as Win32/Gatak.DR and TSPY_GATAK.GTK) was first identified at the end of 2013 and has attracted little public attention. The malware was used as a data stealer to compromise systems of companies operating in various industries, including healthcare, education, and manufacturing. The authors of the malware are exploiting digital steganography to keep the information-stealing under the radar and avoid detection.”]
Source: http://securityaffairs.co/wordpress/37856/malware/stegoloader-malware.html