VirSecCon CTF Steganography Writeups

1) Stegosaurus (70)

DESCRIPTION-

Scientists are struggling with a new mystery: we thought the dinosaurs were gone, but this one has returned! Hmmm... can you solve this mystery?
Download the file below:
stegosaurus.png

SOLUTION::
→ Use commands-
          ⇒ Use website https://georgeom.net/StegOnline/image to convert the color palette of this image
          ⇒ Use the LSB Half option to change color palette
                                             OR
          ⇒ Install tool stegsolve.jar using commands
                    wget http://www.caesum.com/handbook/Stegsolve.jar -O stegsolve.jar
                    chmod +x stegsolve.jar
                    mv stegsolve.jar /bin
          ⇒ Execute it using command- stegsolve.jar, use File option, choose image, use arrows to see the text by changing colors

→ Flag- LLS{you_stegsolved_the_mystery}

2) Winter Wonderland (80)

DESCRIPTION-

It’s the holiday season! But hmm… they must be hiding something under all that cheer!
Download the file below.
winter_wonderland.txt 

SOLUTION::
→ Use commands-
       ⇒ apt install stegsnow to install stegsnow tool
       ⇒ use command stegsnow winter_wonderland.txt to get flag

→ Flag- LLS{let_it_snow_baby_let_it_reindeer}

3) WhitePages (80)

DESCRIPTION-

I stopped using YellowPages and moved onto WhitePages… but the book they gave me is all blank!
Download the file below.
whitepages.txt

SOLUTION::
→ Use commands-
     ⇒ cat whitepages.txt
     ⇒ copy the content of above file yet it is blank
     

    ⇒ use the following script and name it as whitepages.py (or any other name) but replace the content of text variable with above copied text-

# coding=utf8

text = "                                                                                                                                                                                                                                                                                                                                                                                                                   "

firstType = ' '

secondType =  ' '

binaryString = ''

for char in text: #Foreach char

if char == firstType: #Check if it is the first type

binaryString += '0' #Mark it as 0

else:

binaryString += '1' #Mark it as 1

print(binaryString) #Print result

   ⇒ Now, execute above script using this command to convert binary to ascii- python3 whitepages.py | cat | tr -d '\n' | perl -lpe '$_=pack"B*",$_' > ascii.txt
   • Here, 'tr' will delete all newline characters, and the perl command converts to binary
   ⇒ cat ascii.txt 

                                                                            OR
     ⇒ Execute above script

    ⇒ Copy the content of above script after execution
    ⇒ Use this website to convert above copied binary text to ascii- https://www.rapidtables.com/convert/number/binary-to-ascii.html

→ Flag- LLS{whitespace_steganography_in_the_empty_space}

4) Elessbe (80)

DESCRIPTION-

Ah, bonjour mon bon ami! Bienvenue à la capture du drapeau! J’ai entendu dire que vous étiez fan de la stéganographie! Avez-vous déjà entendu parler d’un outil appelé zsteg?
Download the file below:

elessbe.png 

SOLUTION::
→ Use commands-
     ⇒ Use this command to install zsteg tool- gem install zsteg

     ⇒ Use command- zsteg elessbe.png to get the flag

→ Flag- LLS{lsb_est_mon_bon_ami}

I hope, this post helps you solve more CTFs and learn new techniques.

Stay tuned for more writeups!!!

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