Somebody used a "set of valid Twitter credentials" to redirect Twitter visitors to an Iranian opposition Web site, Tom Daly, chief technology officer at Dyn, told Wired News.
From our perspective, it was a perfectly valid username-and-password combination that was logged in with. The only credentials that were compromised were Twitter's.
There is no word on which Twitter employee account was breached.
As noted on our Network Security Edge site last week, a group calling itself the Iranian Cyber Army hijacked Twitter and an opposition Web site and replaced logos and text with its own images.