A group of hackers, known as Shadow Brokers, claim to have stolen a collection of malware files from a group linked to the US National Security Agency (NSA).
The hackers announced they are holding a bitcoin auction and say they will give the code to the highest bidder.
Experts believe a sample they have released for verification may be genuine.
Whistle-blowing website, Wikileaks, also claimed to have the data.
No end date for the auction has been declared, however the group says it will send decryption instructions to the winner when they feel it's "time to end".
Stephen Murdoch, cyber security expert from University College London told the BBC: "It is extraordinary that a government based (or at least government supported) group would get comprehensively hacked, but there is evidence indicating that this may have actually happened.
"Now that the vulnerabilities that the group were exploiting have been disclosed, they will be fixed and new ones will have to be discovered, at significant expense.
"However, if indeed these techniques were used by the NSA, they will be very worried that there is now enough information leaked that would allow forensics experts to attribute hacking attacks to the NSA, both disrupting ongoing operations and causing embarrassment."
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