On December 27, Coinbase, a Bitcoin exchange market and wallet service, and on December 28, Blockchain.info, another similar service, suffered DDoS attacks that brought some of their servers offline.
The attacks were carried out by two hackers, An0CBR and L7, who also seem to have participated in the DDoS attacks against the Steam network.
While many hacking outfits tweeted that they were responsible for the attack, most of them mysteriously deleted their tweets the days following the Steam DDoS, leaving only the An0CBR and L7 messages, which also seem to coincide with the moments when the Steam Store started to experience problems.
http://news.softpedia.com/news/meet-an0cbr-the-scourge-of-bitcoin-payment-portals-498307.shtml