Duqu is successor of the famous computer worm Stuxnet (see Stuxnet). The malware was discovered in 2011 by the Laboratory of Cryptography and System Security at the Budapest University in Hungary. Experts assume that the malware was either written by the Stuxnet authors or that the authors had access to the Stuxnet source code. Either way, the computer worm showed a very similar structure. Other than Stuxnet, Duqu was probably written mainly for espionage purposes to get a better understanding of network structures and develop better methods for an attack.