A hacker group that calls itself “The Dark Overlord” claims it has access to thousands of secret files regarding the September 11, 2001 terrorist attacks that struck the United States. The group threatens to make the sensitive information public if they are not paid a substantial ransom in the form of Bitcoin.

In a (now deleted) announcement posted on Pastebin, the group claimed that it hacked Hiscox Syndicates Ltd, Lloyds of London, and Silverstein Properties in order to obtain the information.

“The Dark Overlord” also claims that they hacked a “global law firm handling multiple cases related to 9/11 attacks”. In an interview with Motherboard, a Hiscox Group spokesman confirmed that a law firm that advised Hiscox had indeed been hacked, although he said that Hiscox’s IT infrastructure had not been compromised.

The Bitcoin ransom is targeted at several entities, ranging from property management firms and insurers to multiple government agencies and several politicians involved in the investigation and litigation of 9/11 related cases. There is also another catch - the subjects have to pay the ransom in public - by announcing and requesting that their “documents and materials be withdrawn from any eventual public release”.

The group released an archive of files that is encrypted, but says they will gradually be releasing keys that unlock parts of it. A section from the note reads: