function phpAds_SessionStart()
{
	global $session;
	if (empty($_COOKIE['sessionID'])) {
		$session = array();
		$_COOKIE['sessionID'] = md5(uniqid('phpads', 1));

        phpAds_SessionSetAdminCookie('sessionID', $_COOKIE['sessionID']);
	}
	return $_COOKIE['sessionID'];
}
Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.