October 27, 2014

Recently, at SDSLabs we participated in ectf’14 hosted by NITK. CTF was fun and we ended up at overall position 10. Here is a ctf for task Pixel Princess.

We are provided with description and link to a file as follows:

Find the princess. Get the flag. bower.tar.gz

First we ran the file command on the given zip which showed that the zip is a gzip compressed data.

file bowser.tar.gz
bowser.tar.gz: gzip compressed data, from Unix, last modified: Thu Oct 16 04:54:39 2014

Running tar -xzvf bowser.tar.gz

provides us with an image bowser.jpg

bowser.jpg

Running strings on the jpg file shows there is a file zipped in image

strings bowser.jpg
.
.
.
MarioCastle.jpgUT
>Tux

This gives a clue that image file MarioCastle.jpg compressed in bowser.jpg file might contain flag.

Running unzip command on bowser.jpg inflates the MarioCastle.jpg file. mariocastle.jpg

This first indicates that MarioCastle.jpg is also a zip file with password, but that leads to nothing. So another option is to use steghide

Running steghide extract -sf MarioCastle.jpg

and entering password for MarioCaste.jpg returns nothing, so we tried steghide on original image bowser.jpg which works :) and gives a tar.gz file, which we extarct to get a jpg file with flag as You_F0unD_m3.

flaga.jpg

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