Steganography, literally translated as covered writing, conceals a secret message in an otherwise innocuous object. The technique dates back to ancient Greece, where it was used to hide messages in sheet music. In a risk-based security program, this picture appears to pose no risk and thus bypasses further scrutiny. Even if you know it poses a risk, two of the three prerequisites to access the secret you still need a password to get to it, and the password is strong enough that it cannot be identified by the secret services.”]
Source: https://www.csoonline.com/article/2120425/steganography-for-dummies.html