Researcher reverse-engineers infamous Stuxnet malware source code, publishes it on Github for all — attack targeted Iranian nuclear facilities and was the first software of its type to cause physical damage

Anyone keeping track of world news in the early 2010s, and reports on tech in particular, has probably heard about Stuxnet. That malware spawned a large number of conspiracy theories — with the kicker that some of them were actually true. The malware targeted Iranian nuclear facilities and is believed to be the first digital worm to cause direct physical damage in meatspace. An unknown security researcher has now published a source code reverse-engineering of Stuxnet in all its glory.

The worm's ultimate target, allegedly a successful one, were industrial controllers from Siemens that were reportedly used in Iranian's Natanz nuclear enrichment plant. Once it reached the target, Stuxnet's payload manipulated the frequency converters in industrial centrifuges, in a bid to subtly damage the rotors — all while keeping the plant staff in the dark by reporting normal operation.

The repository contains build instructions so interested techies can try it out for themselves and learn all about its inner workings. You'll need a Windows XP or Windows 7 virtual machine, and for obvious reasons, you shouldn't configure any network connectivity for it. To witness the full effects of the payload rather than just the spreading mechanisms, you'll need the appropriate Siemens software, and ideally hardware — though we figure that industrial-scale centrifuges aren't exactly common in techies' cable drawers.

In its heyday, Stuxnet spread via three mechanisms. The primary infection vector was USB sticks with Windows shortcuts and autorun.inf files. Upon plugging one of those sticks in, just viewing the drive's contents would immediately trigger infection thanks to a zero-day vulnerability.

Infected systems then autonomously tried to spread the worm further via the network using a zero-day Windows Print Spooler vulnerability that would let an attacker write system files into any machine sharing a printer. It would also copy itself into accessible network shares. To evade Windows driver signature checks, Stuxnet used two digital certificates stolen from Realtek and JMicron.

The worm also had code to inject itself into Siemens software, by way of the WinCC SQL Server database, and embedding its code in Step 7 project files that automatically ran when engineers opened them. Since those files were almost guaranteed to be shared among more than one engineer, it made for an excellent internal infection vector that didn't depend on having network share control.

The final step was taking charge of the DLL that communicated with the actual centrifuges and injecting malicious code into the PLCs (Programmable Logic Controllers) of those machines to stealthily mess with the rotors.

Stuxnet was part of Operation Olympic Games, an alleged coordinated effort between the U.S. and Israel to try and curb Iran's purported progress in creating nuclear weapons at its Natanz facility. The initiative seemingly ran under both the Bush and Obama administrations, and was supposedly a way to dissuade Israel from launching its own preemptive strike against Iran. The software was allegedly developed by both the Pentagon and Israel's Unit 8200, and was reportedly successful in bringing down about 10% of Natanz' centrifuges by ultimately seriously damaging their rotors.

However, the worm had a nasty bug: it didn't have sufficient checks about which environment it was in, and failed to notice it was no longer in a local network environment. When engineers took their laptops home, it escaped out to the internet at large, at which point security researchers worldwide let out a collective "huh, that's odd" and proceeded to investigate. Mercifully, the worm contained a hard-coded self-destruct date set for June 24, 2012.

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