The Project administration application in Siemens SIMATIC WinCC before 7.3, as used in PCS7 and other products, has a hardcoded encryption key, which allows remote attackers to obtain sensitive information by extracting this key from another product installation and then employing this key during the sniffing of network traffic on TCP port 1030.
http://www.siemens.com/innovation/pool/de/forschungsfelder/siemens_security_advisory_ssa-214365.pdf