Post-mortems on recent cyberattacks reveal determined attackers are turning to steganography, the covert hiding of data within seemingly innocuous files. It’s a way of encoding a secret message inside another message, called the carrier, with only the desired recipient able to read it. Steganography has long been used to communicate without the authorities finding out, but now Stegware, the weaponization of steganography by cyber attackers, is on the rise. This is bad news for IT professionals using tools that identify unsafe data since steganography is impossible to detect.
Messages are normally encoded by arranging data as a sequence of symbols. The symbols are obvious, even if you don’t know what they mean. However, with steganography the symbols representing the message are unusual and go unnoticed by everyone except the recipient who knows exactly what to look for.