Trend Micro CTF Programming 100 Challenge Solution

prog-100.sh

#!/bin/bash
ROOT='http://ctfquest.trendmicro.co.jp:43210'
URL="$ROOT/click_on_the_different_color"

function get_coord() {
	IMAGE=$1
	COLOR=`convert $IMAGE -define histogram:unique-colors=true -format %c histogram:info:- | head -2 | tail -1 | grep -oe '#[A-Z0-9]\{6\}'`
	CORDS=`convert $IMAGE txt:- | grep "$COLOR"|head -1|cut -d ':' -f 1`
	X=`echo $CORDS|cut -d ',' -f 1`
	Y=`echo $CORDS|cut -d ',' -f 2`
}

function decode() {
	HASH=`curl --silent $1 | grep -oe "[0-9a-f]\{44\}" | head -n 1`
	echo "Hash:  $HASH"
	IMAGE_URL="$ROOT/img/$HASH.png"
	echo "Image: $IMAGE_URL"
	wget -q $IMAGE_URL -P "images/"
	get_coord "images/$HASH.png"
	echo "Cords: $X, $Y"
	URL="$ROOT/$HASH?x=$X&y=$Y"
	echo "URL:   $URL"
	decode $URL
}

mkdir -p "images"
decode $URL

# Once it reaches the solution, the script gives out errors. At that point, just open the last URL it found to see the flag