Michela Menting, cybersecurity director at technology market experts ABI Research has suggested that hackers gained eBay credentials through "social engineering," a type of psychological manipulation to get people to divulge confidential information.
Menting said: "Finally I think their timely public announcement - two weeks after discovery - helps to reassure not only public opinion, but also their own brand reputation.
"Transparency when dealing with incident response for an event that has affected customers, in this case millions, is highly commendable - it means that eBay takes security seriously."
More top news
A group of friends in Haverhill have left one of their mates with a fractured spine after a prank with a home-made ejector seat went wrong
Temperatures will remain low for most of the country as Britain battles against wintry showers, snow and gales this afternoon.
A giant panda has been caught in camera breaking iron bars and moving into the other cell to have a taste of milk in the next cell.