IF YOU ARE STUDYING FOR A CERTIFICATION EXAM, STOP READING-- THIS IS PURELY ACADEMIC AND WILL ONLY CONFUSE YOU
When I explain steganography to my students, I usually say, “It’s a message in one medium put inside another medium-- more like encoding than cryptography.” I stress that steganography is NOT crypto, even though the topics always seem to be taught coincidentally. I often use the example of Jeremiah Denton, who, as a prisoner of war, blinked the word “torture” in Morse code while being forced to make propaganda films against his country (https://www.youtube.com/watch?v=rufnWLVQcKg). I talk about putting a text message inside the code for a .jpg, and so forth.
As almost always happens, a student in a recent class taught me something I did not know before. But this case was exceptional, because it was something that had simply never occurred to me at all, and I don’t think I’ve ever heard anyone else suggest it:
Trojan horse applications are a form of steganography.
It’s kind of perfect. The malware, which is a message of one medium (the executable), is hidden inside a message of another medium, such as a photo or movie or text document or whatever (sometimes-- there are examples of Trojans where both the malware and its carrier are executables, or there is just one executable with two aspects: one desirable to the victim, and one not).
This is purely a philosophical point: it doesn’t mean anything earth-shattering in the world of INFOSEC. But I love it when a student has a completely new take on some fairly old ideas. Blew me away. Good job, Ann-Kathrin.