Kaspersky Lab discovered that a module from the early 2009-version of Stuxnet, known as Resource 207, was actually a Flame plugin. This means that when the Stuxnet worm was created in the beginning of 2009, the Flame platform already existed, and that in 2009, the source code of at least one module of Flame was used in Stuxnet.
This module was used to spread the infection via USB drives. The code of the USB drive infection mechanism is identical in Flame and Stuxnet. The Flame module in Stuxnet also exploited a vulnerability which was unknown at the time and which enabled escalation of privileges, presumably MS09-025.
Subsequently, the Flame plugin module was removed from Stuxnet in 2010 and replaced by several different modules that utilised new vulnerabilities.
Starting from 2010, the two development teams worked independently, with the only suspected cooperation taking place in terms of exchanging the know-how about the new zero-day vulnerabilities.
Background
Stuxnet was the first cyber-weapon targeting industrial facilities. The fact that Stuxnet also infected regular PCs worldwide led to its discovery in June 2010, although the earliest known version of the malicious program was created one year before that. The next example of a cyber-weapon, now known as Duqu, was found in September 2011. Unlike Stuxnet, the main task of the Duqu Trojan was to serve as a backdoor to the infected system and steal private information (cyber-espionage).
During the analysis of Duqu, strong similarities were discovered with Stuxnet, which revealed that the two cyber-weapons were created using the same attack platform known as the Tilded Platform. The name originated from the preferences of the malware developers for filenames of the form ~d*.* hence, Tilde-d. The Flame malware, discovered in May 2012 following the investigation prompted by International Telecommunication Union (ITU) and conducted by Kaspersky Lab, was, at first sight, entirely different. Some features, such as the size of the malicious program, the use of LUA programming language and its diverse functionality all indicated that Flame was not connected to Duqu or Stuxnets creators. However, the new facts that have emerged completely rewrite the history of Stuxnet and prove without a doubt, that the Tilded platform is indeed connected to the Flame platform.
New findings
The earliest known version of Stuxnet, supposedly created in June 2009, contains a special module known as Resource 207. In the subsequent 2010 version of Stuxnet this module was completely removed. The Resource 207 module is an encrypted DLL file and it contains an executable file thats the size of 351,768 bytes with the name atmpsvcn.ocx. This particular file, as it is now revealed by Kaspersky Labs investigation, has a lot in common with the code used in Flame. The list of striking resemblances includes the names of mutually exclusive objects, the algorithm used to decrypt strings, and the similar approaches to file naming.
Furthermore, most sections of code appear to be identical or similar in the respective Stuxnet and Flame modules, which leads to the conclusion that the exchange between Flame and the Duqu/Stuxnet teams was done in a form of source code (i.e. not in binary form). The primary functionality of the Stuxnet Resource 207 module was distributing the infection from one machine to another, using the removable USB drives and exploiting the vulnerability in Windows kernel to obtain escalation of privileges within the system. The code which is responsible for distribution of malware using USB drives is completely identical to the one used in Flame.
Alexander Gostev, Chief Security Expert at Kaspersky Lab, comments: Despite the newly discovered facts, we are confident that Flame and Tilded are completely different platforms, used to develop multiple cyber-weapons. They each have different architectures with their own unique tricks that were used to infect systems and execute primary tasks. The projects were indeed separate and independent from each other. However, the new findings that reveal how the teams shared source code of at least one module in the early stages of development prove that the groups cooperated at least once. What we have found is very strong evidence that Stuxnet/Duqu and Flame cyber-weapons are connected.