Following an already rough week of falling prices, Forbes reports that Bitcoin suffered another blow yesterday after the detection of a “massive and concerted” distributed denial of service (DDoS) attack on the block chain and related software. The attack focuses on a vulnerability known as “transaction malleability,” which allows records of transactions to be changed, introducing an increased risk of fraud for exchanges.
The source of the attack has yet to be disclosed.
Earlier this week, Japan-based exchange Mt Gox halted trading, citing the transaction malleability bug. The Bitcoin Foundation, the group responsible for developing Bitcoin’s code, swiftly responded to these claims by noting that the bug had been known since at least 2011, and that other exchanges had built code into their systems to compensate for it.
The DDoS attack, detected yesterday, directly targets the malleability issue and is preventing some transactions from being confirmed. It has prompted exchanges Blockchain and Bitstamp to halt Bitcoin trading, a block that is still in place at the time of writing. Other exchanges have not stopped trading but have warned of transaction confirmation delays.
Andreas Antonopoulos, Blockchain’s chief security officer, has told the Coinbase site that the attack was “massive and concerted”, with parallel transactions being executed to create a “fog of confusion” around the currency. Meanwhile, Bitstamp said in a statement that the attack was using transaction malleability “to temporarily disrupt balance checking”.
Concerns over the security of the block chain and the viability of the exchanges’ code has helped to push down Bitcoin prices, which are now trading in the mid-$600 range on Wednesday.