Stuxnet

Stuxnet is a malicious computer worm, first uncovered in 2010, thought to have been in development since at least 2005. Stuxnet targets SCADA systems and is believed to be responsible for causing substantial damage to Iran's nuclear program. Although neither country has openly admitted responsibility, the worm is believed to be a jointly built American/Israeli cyberweapon. Stuxnet specifically targets programmable logic controllers (PLCs), which allow the automation of electromechanical processes such as those used to control machinery and industrial processes including centrifuges for separating nuclear material. Exploiting four zero-day flaws, 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's design and architecture are not domain-specific and it could be tailored as a platform for attacking modern supervisory control and data acquisition (SCADA) and PLC systems (e.g., in factory assembly lines or power plants), the majority of which reside in Europe, Japan and the US. Stuxnet reportedly ruined almost one fifth of Iran's nuclear centrifuges. Targeting industrial control systems, the worm infected over 200,000 computers and caused 1,000 machines to physically degrade. Stuxnet has three modules: a worm that executes all routines related to the main payload of the attack; a link file that automatically executes the propagated copies of the worm; and a rootkit component responsible for hiding all malicious files and processes, preventing detection of the presence of Stuxnet. It is typically introduced to the target environment via an infected USB flash drive, thereby crossing any air gap. The worm then propagates across the network, scanning for Siemens Step7 software on computers controlling a PLC. In the absence of either criterion, Stuxnet becomes dormant inside the computer. If both the conditions are fulfilled, Stuxnet introduces the infected rootkit onto the PLC and Step7 software, modifying the code and giving unexpected commands to the PLC while returning a loop of normal operations system values feedback to the users. In 2015, Kaspersky Lab noted that the Equation Group had used two of the same zero-day attacks, prior to their use in Stuxnet, and commented that: 'the similar type of usage of both exploits together in different computer worms, at around the same time, indicates that the Equation Group and the Stuxnet developers are either the same or working closely together'. Stuxnet, discovered by Sergey Ulasen, initially spread via Microsoft Windows, and targeted Siemens industrial control systems. While it is not the first time that hackers have targeted industrial systems, nor the first publicly known intentional act of cyberwarfare to be implemented, it is the first discovered malware that spies on and subverts industrial systems, and the first to include a programmable logic controller (PLC) rootkit. The worm initially spreads indiscriminately, but includes a highly specialized malware payload that is designed to target only Siemens supervisory control and data acquisition (SCADA) systems that are configured to control and monitor specific industrial processes. Stuxnet infects PLCs by subverting the Step-7 software application that is used to reprogram these devices. Different variants of Stuxnet targeted five Iranian organizations, with the probable target widely suspected to be uranium enrichment infrastructure in Iran; Symantec noted in August 2010 that 60% of the infected computers worldwide were in Iran. Siemens stated that the worm has not caused any damage to its customers, but the Iran nuclear program, which uses embargoed Siemens equipment procured secretly, has been damaged by Stuxnet. Kaspersky Lab concluded that the sophisticated attack could only have been conducted 'with nation-state support.' F-Secure's chief researcher Mikko Hyppönen, when asked if possible nation-state support was involved, agreed 'That's what it would look like, yes.' In May 2011, the PBS program Need To Know cited a statement by Gary Samore, White House Coordinator for Arms Control and Weapons of Mass Destruction, in which he said, 'we're glad they are having trouble with their centrifuge machine and that we – the US and its allies – are doing everything we can to make sure that we complicate matters for them,' offering 'winking acknowledgement' of US involvement in Stuxnet. According to The Daily Telegraph, a showreel that was played at a retirement party for the head of the Israel Defense Forces (IDF), Gabi Ashkenazi, included references to Stuxnet as one of his operational successes as the IDF chief of staff.