Some time ago, a person reached out to Trustwave to get answers regarding some news that he saw about Steganography. After this, I noticed that not many people understand what steganography is and the risks it presents for companies. In this post, I will try to help you understand in an easy way what you need to know about this kind of attack. Here are the questions we were asked:
Steganography is defined as "the art of hiding messages inside media files", in other words, it is the way in which we can hide any message (text, image, audio, …) inside any file (.mp3, .wav, .png, …). This helps people to make sure that only those who know about the presence of the message can obtain it. There are many different methods of performing steganography, but the most famous are the LSB (Least Significant Bit) ones. This kind of method modifies the LSB of different bytes with a bit from the message that will be hidden.
This can be a really big problem since it is a really easy way for getting sensitive information out of organizations without detection. It is easy to download steganography software for embedding files, like contracts or client lists, into any image that looks common, maybe the company's logo, and then take it out of the company without anyone noticing it.
Steganalysis is the art of analyzing files for the presence of data hidden by steganography and potentially recovering that data. There are different steganalytic methods for trying to detect if any file has been modified, so it is a really difficult task to configure an environment where you are 100% safe against these kind of attacks. As I mention in my blog post series about steganography, (And Then? Where is the Risk with Steganography? ) you can configure a detection system in your network to try to prevent those modified files from traversing your network, but as I also mention, it is almost impossible to have a 100% safe environment because of all the various steganography methods that cyber criminals could be using.
Common steganalysis methods are not integral, meaning that each method only works for a specific or a couple of steganographic methods. For example, you can have a module that works with LSB steganographic methods but it cannot detect any other methods. If you want to have a secure network from the perspective of steganalysis, you need to have many different modules for different methods.
Currently there are not a lot of good solutions to prevent steganography and many of them require files to be tested one by one. Because of this, it is really important to start developing new tools that companies can use for automatic detection of steganographic manipulated files.
Of course, if only because there will be many different attacks in the future. Research in the field of steganalysis is still in progress and many different new methods appear every day. People find new techniques for getting what they want all the time, so it is our duty to be prepared to protect our valuable information in the best way we can.
