Stuxnet is computer malware that became the subject of international media in in 2010/2011. The complex malware was believed to have been targeted at Iranian nuclear facilities with the United States and Iran as the two main suspects as the states behind its production.
Symantec published a report on the Stuxnet malware that showed it was targeted at five Iranian facilities over a period of about 10 months.
The malware potentially had the capability to cause damage to Uranium enriching centrifuges, by changing the settings on a programmable logic controller (PLC) developed by Siemens that it targeted.
Symantec said that analysis of Stuxnet shows that the authors of the malware must have hjad extensive knowledge of the facilities being targeted.
It's method of infection was through USB keys, suggesting that the virus may have made its first infection in Iran through an outside contractor who had no idea the USB key was infected by someone.
Iran acknowledges the infections of Stuxnet on many systems within the country but has claimed it had no effect on the country's nuclear facilities. There has been some disputes to that claim, with some analysts saying Iran's nuclear program could have been set back by as much as year if the attack was successful.
Symantec's interesting report on Stuxnet can be read here.