It appears as though there was a double spend attack attempt on the Worldcoin network yesterday. All information points to the issue being caught in time despite the attempted attack. Here are some excerpts from the Worldcoin team:

On the 31st of October 2013 at 17:46:24 the Worldcoin blockchain was attacked to double spend Worldcoins that were earlier exchanged for BTC on MCX Now. The culprit who goes by the name of bazytw (transaction details and IP’s can be found here: http://pastebin.com/s6gMwLRg) logged into MCX Now earlier in the day and exchanged Bitcoin for 60000 Worldcoin.

Later the Worldcoin blockchain was 51% attacked and the Worldcoins were ‘double spent’.

Owing to the sophisticated design of the MCX Now transaction system the website was able to detect the attack and shut off in defense. As a result the owner of MCX Now and the Worldcoin team have been working hard over night to resolve this issue.

The Worldcoin foundation has confirmed that a rollback to before the attack will take place rendering the stolen coins useless. This means that all

Worldcoin wallet users, pools and exchanges need to update their client wallet as soon as possible to ensure they are running on the correct Blockchain.

The Worldcoin Foundation would like to thank members of MCX Now and The MCX Now owner for their support during this time.

WHAT THIS MEANS

Because the situation was picked up relatively quickly the team were able to work quickly to resolve this situation and issue an update to the wallet, but

it has also highlighted the necessity for early warning systems, and failsafes against 51% attacks. The foundation will be looking closely into providing

these systems to ensure the effect of an attack of this nature is greatly diminished in future, and is picked up more quickly. So, all in all, despite the

inconvenience this will cause to many users of Worldcoin, the attacker was thwarted and the network will now be improved which can only prove beneficial in

the long term.