October 2010: Stuxnet, a complex piece of malware designed to interfere with Siemens industrial control systems, was discovered in Iran, Indonesia, and elsewhere, leading to speculation that it was a government cyber weapon aimed at the Iranian nuclear program.
The worm was designed to attack industrial PLCs. Stuxnet functions by targeting machines using the Microsoft Windows operating system and networks, then seeking out Siemens Step7 software. Stuxnet reportedly compromised Iranian PLCs, collecting information on industrial systems and causing the fast-spinning centrifuges to tear themselves apart. Stuxnet reportedly ruined almost one-fifth of Iran's nuclear centrifuges.
Stuxnet’s design and architecture are not domain-specific, and it could be tailored as a platform for attacking SCADA and PLC systems. (Source: theguardian.com)