Authors: Nathan Yam, Jonathan Kartawidjaja
Least Significant Bit (LSB) Stenography refers to an obfuscation technique in which a hidden message is embedded within the least significant bits of each byte within an image.
For demonstration’s sake, recall that an image is really just data (expressed as bytes):
#image
00001101 00001100 01101101 11001101
LSB will take a specific message, and replace the least significant bit of each byte with the bits of the image:
#message to hide
0101
#new image bytes
00001100 00001101 01101100 11001101
Of course, you can do this with any set position of bit. You may also use to wish the Most Significant Bit as well.
Other tools you may have tried but did not yield results include, stegseek, steghide, aperisolve, strings, and exiftool.
In this case, the last two bits (indexed at 6 and 7), are used to encode the secret message. We can use an online tool, such as: https://georgeom.net/StegOnline/upload
We may upload are file and select Extract Files/Data.
If we select the 6th and 7th rows of the RGB bits, and click Go, we will find the flag: