Misc - Invisible Ink (388 pts)

Description

The flag is hidden somewhere in this GIF. You can’t see it? Must be written in transparent ink.

Author: Yes

Hint : Look into the GIF file format itself and how it handles transparency

Attachment :

Solution

We were provided with a gif file called challenge.gif. When i see the title “invisible ink” i instantly thinking of steganography. So, we could use StegSolve to see the hidden content of the gif file

We can see each frame in the gif file using Frame Browser

We find out that there are 2 hidden frame in the gif file. We can save the frame as picture and try to give some filter to the picture to see the content of the picture (you can see that there is a dark part in the middle of the picture, possibly the hidden content)

Using random colour map, we can reveal the hidden content of the frame. We now can stack together the two of them to reveal the full hidden content

Flag

wgmy{d51d8cd900b204e9800998ecf8427e}