A small steganography challenge illustrating basic tricks used to hide data inside images. This post introduces the challenge, walks you through the soliution, and ends by describing how the challenge was created. The solution involves some basic JPG image screening, hexedit surgery, and password cracking with custom wordlists.
Steganography is the practice of hiding information inside other media like images, audio or video files, text, or pretty much anything else. It is different from encryption in that it aims not at making information unreadable but at concealing the very fact that it is there. Steganography and steganalysis (detection of steganography) are long-standing fields of research. Overviews of the field can be found, e.g., in Subhedar/Mankar (2014) or Zielińska/Mazurczyk/Szczypiorski (2014).