An Iranian news agency says the country successfully fended off yet another attack by the Stuxnet worm, according to reports.

The cyberattack allegedly targeted a power plant and other sites in southern Iran over the fall, the BBC and the Associated Press reported today.

Discovered in June 2010, Stuxnet is believed to be the first malware targeted specifically at critical infrastructure systems. It's thought to have been designed to shut down centrifuges at Iran's Natanz uranium enrichment plant, where stoppages and other problems reportedly occurred around that time. The sophisticated worm spreads via USB drives and through four previously unknown holes, known as zero-day vulnerabilities, in Windows.

Stuxnet is just one of several versions of malware aimed at Middle Eastern countries in the past two and a half years. Other examples include Duqu, Gauss, Mahdi, Flame, Wiper, and Shamoon.