Natas [Level 11] - Overthewire

Username: natas11
Password: 1KFqoJXi6hRaPluAmk8ESDW4fSysRoIg
URL: http://natas11.natas.labs.overthewire.org

curl -i -XGET -u natas11:1KFqoJXi6hRaPluAmk8ESDW4fSysRoIg http://natas11.natas.labs.overthewire.org/ | grep -i set-cookie

==> Set-Cookie: data=MGw7JCQ5OC04PT8jOSpqdmkgJ25nbCorKCEkIzlscm5oKC4qLSgubjY%3D

Note that: sudo apt install php

Create file decode cookie

nvim natas11.php

<?php
$defaultdata = array( "showpassword"=>"yes", "bgcolor"=>"#ffffff");
function xor_encrypt($in) {
    $key = base64_decode('MGw7JCQ5OC04PT8jOSpqdmkgJ25nbCorKCEkIzlscm5oKC4qLSgubjY%3D');
    $text = $in;
    $outText = '';
    for($i=0;$i<strlen($text);$i++) {
    $outText .= $text[$i] ^ $key[$i % strlen($key)];
    }

    return $outText;
}

$key = xor_encrypt(json_encode($defaultdata));
echo "$key"
?>

php -f natas11.php

==> KNHLKNHLKNHLKNHLKYBEIOBKOVPTJ–> KNHL

<?php
$defaultdata = array( "showpassword"=>"yes", "bgcolor"=>"#ffffff");

function xor_encrypt($in) {
    $key = 'KNHL';
    $text = $in;
    $outText = '';
    for($i=0;$i<strlen($text);$i++) {
    $outText .= $text[$i] ^ $key[$i % strlen($key)];
    }
    return $outText;
}
$key = base64_encode(xor_encrypt(json_encode($defaultdata)));
echo "$key"
?>

php -f natas11.php

curl -i -XPOST -u natas11:1KFqoJXi6hRaPluAmk8ESDW4fSysRoIg http://natas11.natas.labs.overthewire.org/ -d "bgcolor=#ffffff" -d "submit=" --cookie data=MGw7JCQ5OC04PT8jOSpqdmk3LT9pYmouLC0nICQ8anZpbS4qLSguKmkz

Alright, i got the password! Moving on to level 12!

==> CTF: { natas12:YWqo0pjpcXzSIl5NMAVxg12QxeC1w9QG }