The integrated web server in Siemens SIMATIC WinCC OA before 3.12 P002 January allows remote attackers to execute arbitrary code via crafted packets to TCP port 4999.
https://exchange.xforce.ibmcloud.com/vulnerabilities/90933
http://www.siemens.com/innovation/pool/de/forschungsfelder/siemens_security_advisory_ssa-342587.pdf
http://www.securityfocus.com/bid/65351