docker-vulnerable-dvwa/dvwa/vulnerabilities/sqli_blind/source/high.php

<?php

if( isset( $_COOKIE[ 'id' ] ) ) {
	// Get input
	$id = $_COOKIE[ 'id' ];

	// Check database
	$getid  = "SELECT first_name, last_name FROM users WHERE user_id = '$id' LIMIT 1;";
	$result = mysqli_query($GLOBALS["___mysqli_ston"],  $getid ); // Removed 'or die' to suppress mysql errors

	// Get results
	$num = @mysqli_num_rows( $result ); // The '@' character suppresses errors
	if( $num > 0 ) {
		// Feedback for end user
		$html .= '<pre>User ID exists in the database.</pre>';
	}
	else {
		// Might sleep a random amount
		if( rand( 0, 5 ) == 3 ) {
			sleep( rand( 2, 4 ) );
		}

		// User wasn't found, so the page wasn't!
		header( $_SERVER[ 'SERVER_PROTOCOL' ] . ' 404 Not Found' );

		// Feedback for end user
		$html .= '<pre>User ID is MISSING from the database.</pre>';
	}

	((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}

?>