(Adds confirmation that UgNazi attacked Twitter)
By Gerry Shih and Joseph Menn
SAN FRANCISCO, June 21 Two service outages
within the course of several hours rocked microblogging platform
Twitter on Thursday, as users worldwide reported significant
down-time and slow service across both Twitter's website and
In a tweet issued shortly after 12:17 p.m. PDT (1970 GMT),
the San Francisco-based company blamed the outage - one of its
most severe episodes in recent months - on a "cascading bug" in
one of its infrastructure components.
Twitter issued the statement after UgNazi - an emerging
hacker outfit that recently gained publicity for breaking into
Cloudflare Chief Executive Matthew Prince's personal Google
email account - claimed credit for the service disruption in an
email to Reuters, saying it launched a distributed
denial-of-service (DDoS) attack against Twitter because of the
company's support for the Cyber Intelligence Sharing and
One security professional said the group probably used a
DDoS-for-hire site to launch an attack against Twitter on
Tuesday, but downplayed the likelihood the group was solely
responsible for bringing down the social media network.
"It was mere coincidence," the security professional said.
"The backend of Twitter is having issues, which is unrelated to
the very small attack."
North American traffic levels for Twitter.com sharply
plummeted on two occasions between 8:30 a.m. PDT (1530 GMT) and
11:00 a.m. PDT (1800 GMT), according to data provided by network
analytics company Sandvine.
The first outage lasted between 8:30 a.m. (1530 GMT) and
10:00 a.m. (1700 GMT), data showed.
Twitter acknowledged the disruption in a mid-morning blog
post that was continually revised as the service resumed, only
to fail for a second time before 11:00 a.m.
Tuesday's sustained outage leaves a fresh bruise on a
service that had supposedly shed its unreliable reputation long
As the service resumed on Tuesday, its most dedicated users
quickly hopped back on to crack jokes, express relief and
complain about the interruption - and the fact that, during the
outage, they had nowhere to complain about the interruption.
Founded in 2006, Twitter was plagued in its early years by
frequent outages as its servers struggled to handle the
ever-rising volume of tweets generated worldwide, leaving
frustrated users with its famous "fail whale" error screen.
The company, which has been under pressure to demonstrate a
viable business model, has emphasized improving its reliability
in recent years.
CEO Dick Costolo said this month that Twitter now has 140
million active monthly users.
(Reporting By Gerry Shih and Mauro Whiteman; Editing by Jeffrey
Benkoe, Tim Dobbyn and Andre Grenon)