Bitcoins valued at approximately $2.7 million have gone missing from Silk Road 2, allegedly due to a hack.

Silk Road 2 is the reincarnation of the original Silk Road, an online black market for all things criminal that was shut down by the feds last year. The new site emerged in November and is only accessible to those who have an invite and sign in using the Tor anonymizing service.

But according to a Silk Road administrator known as Defcon, all is not well on the site. In a recent forum post, which was posted online by DeepDotWeb, Defcon said that Silk Road 2 had been hacked and its bitcoins stolen.

"Our initial investigations indicate that a vendor exploited a recently discovered vulnerability in the Bitcoin protocol known as 'transaction malleability' to repeatedly withdraw coins from our system until it was completely empty," Defcon wrote.

According to CoinDesk, transaction malleability is "an attack that lets someone change the unique ID of a bitcoin transaction before it is confirmed on the bitcoin network. The change makes it possible for someone to pretend that a transaction didn't happen, if all the right conditions are in place."

As the International Business Times noted, transaction malleability has been around since at least 2011, but the topic made headlines recently when bitcoin exchange MtGox suspended all withdrawal transactions, citing transaction malleability.

In a Tuesday statement, the Bitcoin Foundation said "we (core dev team, developers at the exchanges, and even big mining pools) are creating workarounds and fixes right now. This is a denial-of-service attack; whoever is doing this is not stealing coins, but is succeeding in preventing some transactions from confirming. It's important to note that DoS attacks do not affect people's bitcoin wallets or funds."

The bitcoin stash on Silk Road 2, meanwhile, was in "hot storage" (or online) rather than cold storage, Defcon said, because "we were planning on re-launching the new auto-finalize and Dispute Center this past weekend, and our projections of order finalization volume indicated that we would need the community's full balance in hot storage."

"In retrospect this was incredibly foolish, and I take full responsibility for this decision," Defcon wrote.

Given that Silk Road isn't exactly a reputable business - allegedly trafficking in drugs, guns, and other unsavory services - it's difficult to feel bad for those who might have lost money. But according to an update on DeepDotWeb, there's also the possibility that this "hack" is actually a scam so that Silk Road administrators can pocket the cash themselves.

"As the time passes there are more and more suspicions that this was in fact a SCAM by the Silk Road staff – and not a hack, we will post more details about it once, and if we get the full picture," DeepDotWeb wrote.

In the post, Defcon apologized profusely and urged the alleged hackers to return the bitcoin. "Whoever you are, you still have a chance to act in the interest of helping this community," he wrote. "Keep a percentage, return the rest. Don't walk away with your fellow freedom fighters' coins."

For more, check out PCMag Live in the video below, which discusses the heist.