WordPress/wp-admin/auth.php

<?php

require_once('../wp-config.php');

/* Checking login & pass in the database */
function veriflog() {
	global $cookiehash;
	global $tableusers, $wpdb;

	if (!empty($_COOKIE['wordpressuser_' . $cookiehash])) {
		$user_login = $_COOKIE['wordpressuser_' . $cookiehash];
		$user_pass_md5 = $_COOKIE['wordpresspass_' . $cookiehash];
	} else {
		return false;
	}

	if (!($user_login != ''))
		return false;
	if (!$user_pass_md5)
		return false;

	$login = $wpdb->get_row("SELECT user_login, user_pass FROM $tableusers WHERE user_login = '$user_login'");

	if (!$login) {
		return false;
	} else {
		if ($login->user_login == $user_login && md5($login->user_pass) == $user_pass_md5) {
			return true;
		} else {
			return false;
		}
	}
}

if ( !veriflog() ) {
	header('Expires: Wed, 11 Jan 1984 05:00:00 GMT');
	header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');
	header('Cache-Control: no-cache, must-revalidate');
	header('Pragma: no-cache');
	if (!empty($_COOKIE['wordpressuser_' . $cookiehash])) {
		$error="<strong>Error</strong>: wrong login or password.";
	}
	$redir = 'Location: ' . get_settings('siteurl') . '/wp-login.php?redirect_to=' . urlencode($_SERVER['REQUEST_URI']);
	header($redir);
	exit();
}

?>