Servers for both EVE and Dust are now back online, with a statement from CCP offering some further insight into what caused the outage.
A blog post from the Icelandic developer has explained that a back-end support system was exploited to facilitate the attack, clarifying that no customer data was vulnerable at any time.
"While we initially reopened EVE Online and DUST 514, at 14:51 UTC we became aware of additional information led us to re-evaluate our decision. With the highest sense of precaution we took the decision to take Tranquility and associated websites back down for further investigation and an exhaustive scan of our entire infrastructure.
"What we can now confirm is that a person was able to utilize a vulnerability in one of the back-end services that support the operation of the Tranquility server. This vulnerability has now been secured and thoroughly tested.
"We would like to stress that at no time was customer data compromised or accessible in any way."
CCP has taken the servers for both EVE Online and attached free-to-play shooter Dust 514 offline following a denial of service attack.
Both games remain offline currently, with the developer thanking fans for their patience as an investigation is conducted into the origins of the attack. A statement on the game's Facebook page announced the attack to players this morning.
"At 02:05 GMT June 2nd, CCP became aware of a significant and sustained distributed denial-of-service attack (DDoS) against the Tranquility cluster (which houses EVE Online and DUST 514) and web servers," reads the post.
"Our policy in such cases is to mobilize a taskforce of internal and external experts to evaluate the situation. At 03:07 GMT, that group concluded that our best course of action was to go completely offline while we put in place mitigation plans.
"While we initially reopened EVE Online and DUST 514, we have since re-evaluated. With the highest sense of precaution we have taken Tranquility and associated websites back down for further investigation and an exhaustive scan of our entire infrastructure. We will update you more frequently via our Twitter feed, however, an extended service interruption of several hours is expected as this process should not be rushed."
For more on CCP, EVE Online and the forthcoming update to the game, see our interview with the company's David Reid.