The software driving Bitcoin transactions on the Internet has been updated to fix a weakness that contributed to the downfall of Mt. Gox, once one of the biggest exchanges for the digital currency.
Version 0.9.0 of the "Bitcoin Core" software, the Bitcoin infrastructure software previously known as Bitcoin-QT, contains five separate changes designed to make so-called transaction malleability attacks harder to pull off. As Ars explained last month, the attacks work by flooding exchanges with large numbers of malformed transactions that are similar, but not identical, to legitimate transactions that have already been made. Exchanges that trust one or more of the phantom records instead of the entries in the official Bitcoin blockchain can fall out of sync with the rest of the network and must recalculate their fund balances once the mistakes become apparent.
Attacks that abused the weakness caused several exchanges to suspend cash withdrawals. Tokyo-based Mt. Gox never recovered. Three weeks ago, it filed for bankruptcy after claiming to lose $468 million, $412.5 million of which it said belonged to customers.