Let's give an example about how steganography can be a really big risk for our safety. Let's suppose that a criminal group wants to send some messages between members. Of course, they do not want the police to realize the content of the messages. So, criminal A wants to give some details to Criminal B on how to kidnap a person, but needs to avoid being tracked by the police and realizing what they are planning. If criminal A hides the instructions in a normal image, like a sight seen, and send it using an IM application, it will be almost impossible to detect it since the image does not seem suspicious. Once the image arrives to criminal B, he can execute the inverse steganographic method, decode the secret message for obtaining all the instructions and commit the crime without alerting authorities.
Now let's consider another scenario that might be more common in our daily life where steganography is used by an insider in order to leak sensitive company information. Almost all the common IT security protections cannot help us avoid this kind of problem since most of them do not have steganalysis features. Companies can lose important information (like customer lists, contracts, source code, etc.) without knowing about it.
Let's suppose that employee A's computer has a highly confidential file that contains some company's secrets. He knows that if he sells that file to another company he will be paid a large bribe. The company has Data Loss Prevention (DLP) and other security tools in place that check all data leaving the company's intranet. This means that employee A needs to find a way for cheating these tools. He uses a steganographic method for hiding the file in the company's logo image and then sends an email with that image attached so it can exit the company intranet undetected. Once the information is outside of the intranet it is also outside company control and he can do whatever he needs with the information even sell it to whomever he wants.
We need to use a steganalysis module in our networks to prevent this kind of attack. The easiest way to implement it is to run a steganalysis suite in one of our devices which analyses the files that are trying to leave the intranet. The next image shows a basic network with a dedicated server for analyzing the files using a steganalysis module.
Unfortunately this ideal scenario does not really exist in reality. One of the problems that we have these days is that there are not a lot of tools that include steganalysis modules, so it is a little difficult to protect out networks from this kind of attacks. There are different tools for steganalysis but almost all of them require a person to manually use them. It is really important to start working a little more in this field for developing useful tools for preventing this kind of attack.
These are really simple examples about the use of steganography. I hope you understand a little more about it and can visualize the impact that it can have in our lives. Remember that we can lose a lot of valuable data if we are not prepared for these kinds of attacks. If you have any question please leave a comment and I will reply as soon as possible.