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“The Annex” case study: the technical perspective'

After several years of intensive investigations by the Cybercrime Department of the Bavarian State Criminal Police Office and the Bavarian Central Office for the Prosecution of Cybercrime in Germany along with several international partners like the AFP, FBI and NCA, three darknet platforms were shut down and administrators as well as other high value targets were arrested.

The darknet platforms consisted of three chat sites in total. Two of them could be accessed very easily and without registration. While on "TorPedoChat" communication was happening in English language, "TorpedoChatDE" was aimed specifically at German-speaking users. In the chats, users shared child sexual abuse material and talked about their addictions. They also engaged in role-playing games and even arranged to sexually abuse children.

On the other hand, the perpetrators used the highly conspirative darknet platform "The Annex". Several chat rooms were set up on this chat site for different preferences. One of the rooms was named "No Limits", in which even videos of children who had been killed and subsequently abused could be shared. Several thousand users from around the world were active on the platforms. On all three darknet sites combined, they posted around 120,000 messages and shared more than 20,000 CSA videos and pictures per month.

Our main contributions to the success of the investigations were technical measures on the server infrastructure of the darknet sites, like tor tracking, running wire-taps and forensic analysis of server images obtained. The data, for example, gave a better understanding of the groups hierarchical structure and a list of all registrations. By attacking password hashes, around 70% of all passwords could be recovered and cross-checked with other data, for example from data leaks, for identification purposes.

The core group of administrators could be arrested by the FBI in the USA by November 2022. Several moderators were arrested at the same time, for example in the UK and Germany.


Dr Michael Salter.jpg

Prosecutor - BLKA

Stephan Schäl

Bio - Rouse.jpg

Georg Berger

Detective Chief Inspector - BLKA

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