The HMI web server in Siemens WinCC flexible 2004, 2005, 2007, and 2008; WinCC V11 (aka TIA portal); the TP, OP, MP, Comfort Panels, and Mobile Panels SIMATIC HMI panels; WinCC V11 Runtime Advanced; and WinCC flexible Runtime has an improperly selected default password for the administrator account, which makes it easier for remote attackers to obtain access via a brute-force approach involving many HTTP requests.
http://www.us-cert.gov/control_systems/pdf/ICSA-12-030-01.pdf