Some of the internet's biggest stories have no ending. These are the mysteries where we know what happened but not who did it or why.
The main ones have full write-ups: the creator of Bitcoin, the Cicada 3301 puzzle hunts, and the person behind the xz backdoor. Shorter entries below cover a broadcast hijacking, a coded sculpture, a stream of nonsense posts and a group that leaked hacking tools.
In every case below, people have proposed explanations, but none has been proven. Where a name has been suggested and denied, the pages say so and avoid presenting guesses as fact.
The mysteries
- Satoshi Nakamoto — The anonymous creator of Bitcoin, who vanished in 2011.
What we know: Published the Bitcoin paper in October 2008, launched the network in January 2009, and wrote online until 2011.
Still unknown: Who or how many people they were. Researchers estimate they hold around a million bitcoin that have never moved. - Cicada 3301 — A series of internet puzzles that recruited codebreakers and then fell silent.
What we know: Three rounds of puzzles in 2012, 2013 and 2014, with a further round in 2017, mixing ciphers, hidden messages and posters in real cities.
Still unknown: Who was behind them and what they wanted. Much of the final book, the Liber Primus, is still unsolved. - Jia Tan and the xz backdoor — A patient plan to hide a backdoor in software used on Linux servers worldwide.
What we know: A contributor using the name Jia Tan gained trust over about two years, and in 2024 hidden code was found in xz versions 5.6.0 and 5.6.1.
Still unknown: The real identity and goals of Jia Tan, and whether it was one person or a team. - The Max Headroom broadcast hijacking — Two Chicago TV stations were hijacked on live television.
What we know: On 22 November 1987 someone interrupted two stations' broadcasts for a few minutes, once with a person in a Max Headroom mask.
Still unknown: Who did it. Nobody has ever been identified. - Markovian Parallax Denigrate — A flood of strange posts on Usenet that nobody could explain.
What we know: Starting in 1996, posts stuffed with random-looking phrases appeared on newsgroups under that title.
Still unknown: Why they were sent. Theories range from a spam test to a hidden message, and none is confirmed. - Kryptos — A coded sculpture outside CIA headquarters with one section still unsolved.
What we know: Artist Jim Sanborn's sculpture carries four coded passages. Three have been solved.
Still unknown: The meaning of the fourth passage, which has resisted codebreakers for decades. - The Shadow Brokers — A group that leaked a trove of powerful hacking tools and then disappeared.
What we know: The group auctioned and leaked tools that researchers linked to the NSA's Equation Group, including the exploit later used in WannaCry.
Still unknown: Who they were or how they got the files.
Frequently asked questions
What is the biggest internet mystery?
The identity of Bitcoin's creator, Satoshi Nakamoto, is usually considered the biggest.
Has Cicada 3301 been solved?
The early puzzles were solved by participants, but the final book, the Liber Primus, has been only partly solved and the creators have never been identified.
Do you name people as suspects?
Only where public reporting or court rulings exist, and we say when the person has denied it.