Squid Game

What is the phone number on the invitation card in Squid Game? (Research this online!) (5 points)

Answer: 86504006
Can you extract something from the invitation card file? What is the name of the file? (5 points)
```
steghide extract -sf ./Invitation\ Card.jpg
```
Using the password as the phone number from above, we can successfully extract the invitation data.

Answer: Dalgona.png
What hint text can be discovered in the final file? (5 points)

My first thought was to run strings on the image, but no text of utility was returned. Nothing useful was given by exiftool either.
```
wget http://www.caesum.com/handbook/Stegsolve.jar -O stegsolve.jar
chmod +x stegsolve.jar
java -jar stegsolve.jar
```
Going through all the options for "Image Combiner" did not give any hints. I did find something on Red plane 4 when clicking through the planes via the arrows at the bottom of the tool: "Red Pixel".

Answer: Red Pixel
What is the final flag? (5 points)

Whenever we look at the "Colour Inversion (Xor)" plane, we can see that there's a column of red pixels that stands out:

So I thought extracting all the red bit planes would yield something useful, extracted by column. Unfortunately, there was nothing interesting in the output. I didn't see anything useful when siftinbg through the various offsets in the "Stereogram Solver" either.

Thanks to a little tip by @ItsAnkitsss, I learned that I should use the site pixspy.

Answer: SBT{}

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