...Scan items and plugins are frequently updated and can be automatically updated. Nikto is not designed as a stealthy tool. It will test a web server in the quickest time possible and is obvious in log files or to an IPS/IDS. However, there is support for LibWhisker's anti-IDS methods in case you want to give it a try (or test your IDS system). Not every check is a security problem, though most are.