Summary

Hey check out this awesome gif I found!

Steps

The gif file has one image that contains a flag near the top right corner, but as you see its quite difficult to see without modification.

I used the utility covert from ImageMagick to expand the gif into individual images. I used the following syntax to achieve this.

convert chall.gif chall.png

Now, I had multiple chall.png files for each frame of the gif.

For In Between The Lines 002, there is another gif file that shows part of the flag in each frame as seen below.

I used the same technique to convert the files into individual files and then manually typed the flag.

The final result was: flag{W31c0M3_70_7H3_111_80X_0F_Ur_UN1M461N4813_P41N_4150_15N7_U51N6_4_0Cr_50_C001_11K3_17_15_U53FU1}