Digital anti-terrorism activists Ghost Security Group claims to have uncovered several Bitcoin addresses being used by ISIS, with one account containing as much as $3 million in U.S. dollars.

Since cryptocurrency started gaining popularity there’s been concerns it could pay for something more sinister than bad MDMA on the dark web. In 2014, a blog associated with ISIS wrote how a “global jihad” could be funded by Bitcoin, and indeed that now seems to be the group’s digital money of choice.

An anonymous member of Ghost Security Group confirmed to Bitcoin News Service NewsBTC that the group has been tracking funds on the deep web and working to shut them down.

In an email exchange the member writes:

“The Islamic State does use cryptocurrencies as a form of income to fund their ongoing operations and we have managed to uncover several Bitcoin addresses used by them. One of the accounts we analyzed was found to contain 3 million U.S. dollars worth of Bitcoins.”

Cryptocurrency isn’t without its drawbacks. Its value is unpredictable, as it grows increasingly common so will methods to track it. Like any currency, there’s a threat of it being stolen, and it can be difficult to convert to a sovereign currency. But its benefits — global reach, speed, anonymity, and ease of use, among others — are highly attractive to terrorist groups. It’s uncertain whether ISIS actually has the capacity to mine Bitcoin itself yet, but donations are coming in regularly.

Tips can be submitted to the group here and it recommends you not try and prank them. If they can find ISIS accounts they can probably find you.

Photos via Getty