A group of black hat hackers claimed today that they had breached Equation Group, a shadowy hacking team believed to be an arm of the National Security Administration.

The hackers, who call themselves the “Shadow Brokers,” have offered free “proof” that they had taken cyberweapons from Equation Group. Shadow Brokers claimed to have even more valuable information as well that they are selling to the highest Bitcoin bidder.

“We find many many Equation Group cyber weapons,” Shadow Brokers writes in a Tumblr post explaining their hack. “You see pictures. We give you some Equation Group files free, you see. This is good proof no? You enjoy!!! You break many things. You find many intrusions. You write many words. But not all, we are auction the best files.”

The security firm Kaspersky Labs first outed Equation Group in 2015 as a hacking group “that surpasses anything known in terms of complexity and sophistication of techniques, and that has been active for almost two decades.” Kaspersky Labs’s best guess is that Equation Group was connected to the NSA, mostly because of their links to Stuxnet, and Flame, two digital attacks linked to the U.S. Government.

Hacker and security researcher Claudio Guarnieri believes that the information could be credible.

Shadow Box started accounts on Twitter, Tumblr, Github, and Reddit today to spread the knowledge of their auction, The Daily Dot reports. Yet due to how new the hack is and the sensitive information included, there’s a lot of skepticism as to whether or not the hack is real. If it is, the information might be dated considering it references code names first mentioned in Edward Snowden’s NSA leak.

So far, bidders and the “wealthy elite” that Shadow Box is targeting with this hack haven’t taken the bait. Shadow Box mentioned if it gets one million bitcoin ($566 million at the current exchange rate), it will make all of the files public. So far it has received bids for a total of less than the bitcoin equivalent of $100.

The timing of the hack is conspicuous in light of the hack on the Democratic National Convention at the end of July. Of course, there could be a wider conspiracy afoot altogether.

Either way, you can bet the spies at the NSA don’t like being spied on.

Photos via Getty Images / Handout