The service appeared to be functioning normally on Friday morning.
In a blog post late Thursday evening, Biz Stone, a founder of Twitter, said hackers had changed the records for the company’s Web addresses in the Domain Name System, which function as a directory for handling data requests. The hackers redirected those requests to non-Twitter servers.
“Twitter’s DNS records were temporarily compromised but have now been fixed,” Mr. Stone said. “We are looking into the underlying cause and will update with more information soon.
My colleague Robert Mackey rounds up various reports on the causes of the attack over on The Lede blog.
Mashable, a leading technology blog, attributed the outage to a malicious attack from a group claiming to be the “Iranian Cyber Army,” which replaced Twitter’s logos and text with its own imagery.
Twitter has not yet confirmed this report.
Not long ago, service outages and interruptions on Twitter were frequent enough that the cutesy graphic of a whale being carried by a flock of birds that appeared when the site was down earned the nickname “Fail Whale” by users.
But in recent months the site has done much better.
The last major outage occurred in August, when a two-pronged wave of attacks crippled the service, leaving it completely inaccessible by users for an entire day.
That denial-of-service attack, which was directed at a single blogger who had written posts voicing support for the Republic of Georgia in that country’s continuing conflict with Russia, was lobbed at Facebook, LiveJournal, YouTube and other social networks, in addition to Twitter.
But Twitter was the only service that was completely overwhelmed by the cyberattack, and it struggled to get back online in its aftermath.