Scan an image with StegDetect @ varying sensitivity levels
Check for Outguess, PixelKnot and known steganography strings & artifacts
StegDetect can check for JSteg, Outguess, JPHide, Invisible Secrets, F5 Stego, and Appended data
Adjust the Sensitivity Level for better results.
Baseline: 1, Outguess: 4.3, JPHide: 6.2
Version: Outguess-0.13 and Outguess-0.2
LSB Steganography on RGB PNG/Bitmap images
LSB Steganography in JPEG images with non-progressive decoding
I created Steg0saurus Chex after doing some ARG Puzzle Solving. Things like the Cicada 3301 puzzles and others lead me down the path of steganography and the tools associated. To make it easier for others to try their hand at these things (and possibly stumble onto some sort of covert communication taking place over public social media sites), I created a simple interface that allows anyone from anywhere in the world to access a variety of Linux command line tools that I (and others) use to perform steganographic functions. This enables people with little to no "tech knowledge" to check images for potential messages or embed messages themselves. If you're able to upload a profile picture to a social media site, you can use this tool!
Steganography is an ancient word that translate to something along the lines of "hidden writing". It is simply the act of hiding something in plain sight. The technique is as old as time and the processes are numerous. In the digital age, steganography is generally referred to in regards to image or audio steganography--the act of embedding or hiding a secret message inside the data of an image or soundfile. In the grand scheme of things, data is just data--whether that data represents a song or a picture, it's still (at its absolute core) a bunch of 1s and 0s.
There are new methods of steganography being developed and theorized all the time, so detecting it is quite literally like looking for a needle in a haystack. And worst of all, even if you find a needle... there's no guarantee it's THE ONLY needle in there!
Many different methods and programs exist to try and suss out whether an image is steg'ed or not, but here's a couple links to research papers on the reliability of certain tools:
Recently, I found this awesome little gem: https://data.csafe.iastate.edu/StegoDatabase
This is a database of clean & steg'ed images for use in testing and training.