A news item that keeps bubbling up in the information security world is about STUXNET, a malicious piece of software that was originally said to target nuclear reactors in Iran. This might seem a bit odd, as most malicious software is pretty random, infecting anything it comes across. This malware seems to have had a very particular purpose.

It has been well known since its discovery that STUXNET targeted SCADA (Supervisor Control and Data Acquisition) systems, which are used in industrial process control environments, essentially providing electro-mechanical control over a logical network, be that the Internet or via a dial-up modem. SCADA systems are used all over the place, controlling sluice gates, traffic lights and in nuclear reactors. In general, these systems are kept as far away from public networks as possible, to prevent the infection of the networks they reside on, as the results can often be catastrophic.

However, an article in The Register, referencing a Symantec blog, detailed that this malware was even more specifically targeted. In summary, the article explains how STUXNET was aimed at frequency converter drives made by Fararo Paya of Iran and Vacon of Finland, both, presumably, used in the Iranian nuclear programme. Not only that, but only those drives that operate at very high speeds, between 807 Hz and 1210 Hz. It also had the capability to spread via USB sticks, thereby not being dependent on an accessible process control network.

The code reveals that the malware would change the output of the drives, intermittently, over a period of months, thereby disrupting whatever they were controlling, albeit subtly. Interestingly, this type of equipment has export restrictions placed on it by the US as they can be used in the centrifuges that enrich uranium.

One has to assume that the purpose of the malware was to sabotage the Iranian uranium enrichment programme in such a way as to not be discovered.

The reason it got discovered was that it was too successful. Tens of thousands of systems across the world have been infected by STUXNET, notably in Indonesia.

Given the level of targeting and pre-requisite knowledge of uranium enrichment, was this written by the regular clan of virus writers, whose main aim is quick profit? Unlikely.

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