Duqu is a sophisticated new threat which appears to have been written by the same group who authored Stuxnet (one of the most advanced malware attacks developed to date)
W32.Duqu – Advanced malware threat modeled after Stuxnet
QUOTE: Duqu is essentially the precursor to a future Stuxnet-like attack. The threat was written by the same authors (or those that have access to the Stuxnet source code) and appears to have been created since the last Stuxnet file was recovered. Duqu’s purpose is to gather intelligence data and assets from entities, such as industrial control system manufacturers, in order to more easily conduct a future attack against another third party. The attackers are looking for information such as design documents that could help them mount a future attack on an industrial control facility.
Duqu uses HTTP and HTTPS to communicate with a command-and-control (C&C) server that at the time of writing is still operational. The attackers were able to download additional executables through the C&C server, including an infostealer that can perform actions such as enumerating the network, recording keystrokes, and gathering system information. The information is logged to a lightly encrypted and compressed local file, which then must be exfiltrated out.