Siemens released a security update to address the Heartbleed vulnerability in SIMATIC WinCC Open Architecture, a SCADA (supervisory control and data acquisition) system that's used in a large number of industries to operate processes, machines and production flows. Heartbleed is a critical security flaw discovered earlier this month in OpenSSL, the most popular implementation of the TLS (Transport Layer Security) and SSL (Secure Sockets Layer) protocols.