SilverStripe Vulnerability on 'isDev', 'isTest' and 'flush' $_GET validation

When a secure token parameter is provided to a SilverStripe site (such as isDev or flush) an empty token parameter can be provided in order to bypass normal authentication parameters.

For instance, http://www.mysite.com/?isDev=1&isDevtoken will force a site to dev mode. Alternatively, “flush” could also be used in succession to cause excessive load on a victim site and risk denial of service.

The fix in this case is to ensure that empty tokens fail the validation check.