exploit.sh

#!/bin/bash

# Function to decode base64 data repeatedly until fully decoded
decode_multiple_times() {
    local encoded_data="$encoded_data"
    local previous_data=""
    local phase=1

    echo "Encoded Data: $encoded_data"
    
    # Loop until the data stops changing (fully decoded)
    while true; do
        echo "-----------------------------------------------------------------"
        # Try to decode the data
        local new_decoded_data
        new_decoded_data=$(echo "$encoded_data" | base64 -d 2>/dev/null)

        # Check if the decoding was successful
        if [[ $? -ne 0 ]]; then
            echo "Decoding success!!!"
            echo "The flag is: $encoded_data"
            break
        fi

        # Check if the data has stopped changing
        if [[ "$new_decoded_data" == "$previous_data" ]]; then
            break
        fi

        # Update the data for the next iteration
        previous_data="$encoded_data"
        encoded_data="$new_decoded_data"
        echo "Decoded phase $phase: $encoded_data"
        ((phase++))
    done

    echo "$decoded_data"
}

#  Check if a valid url is provided as an argument
if ! [[ "$1" =~ ^(https?://)?([a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.[a-zA-Z]{2,})(:[0-9]+)?(/.*)?$ ]]; then
    echo "Error: Please provide the valid file's URL as an argument."
    echo "Usage: $0 <url>"
    exit 1
fi

url=$1
wget -q $url -O file

encoded_data=$(cat file)
decoded_data=$(decode_multiple_times "$encoded_data")
echo "$decoded_data"