exploit.sh

#!/bin/bash

# Validate the URL format
if ! [[ "$1" =~ ^https:\/\/([A-Za-z0-9-]+\.)*picoctf\.net\/.*\/challenge\.zip$ ]]; then
    echo "Error: please provide a valid URL as an argument."
    echo "Usage: $0 <URL>"
    exit 1
fi

URL="$1"

function get_flag() {
    # Download the challenge.zip
    wget -q "$URL" -O challenge.zip
    if [ $? -ne 0 ]; then
        echo "Error: Failed to download file."
        exit 1
    fi

    # Unzip the downloaded file
    unzip -q challenge.zip
    if [ $? -ne 0 ]; then
        echo "Error: Failed to unzip file."
        exit 1
    fi

    # Check if the directory 'drop-in' exists after unzipping
    if [ ! -d "drop-in" ]; then
        echo "Error: 'drop-in' directory not found."
        exit 1
    fi

    # Change directory to 'drop-in'
    cd drop-in || exit

    # Extract the flag from the git show output
    git show | sed -r 's/\x1b\[[0-9;]*m//g' | grep '^-' | sed 's/^-//' | grep -oE 'picoCTF{.*?}'
    if [ $? -ne 0 ]; then
        echo "Error: Failed to extract flag."
        exit 1
    fi
}

# Call the function and store the flag
flag=$(get_flag)

# Check if the flag is found and print it
if [ -z "$flag" ]; then
    echo "Error: Flag not found."
else
    echo "$flag"
fi