The firm says it is „embarrassed and sorry“ for the hack that saw celebrities tweet a Bitcoin scam.
Twitter says hackers manipulated staff and used their credentials to access internal systems in a cyber-attack of celebrity accounts earlier this week.
The hackers had „accessed tools only available to our internal support teams“ to target 130 accounts, it said.
They reset the passwords of 45 accounts before logging in and sending tweets.
The security breach saw accounts including those of Barack Obama, Elon Musk, Kanye West and Bill Gates tweet a Bitcoin scam to millions of followers.
The FBI is investigating the hack and Twitter said it would support all efforts to find those responsible.
„We’re embarrassed, we’re disappointed, and more than anything, we’re sorry,“ the company said. How did the attack unfold?
In an update, Twitter said the attackers had targeted certain Twitter employees through a „social engineering scheme“.
„In this context, social engineering is the intentional manipulation of people into performing certain actions and divulging confidential information,“ it said.
A small number of staff had been successfully manipulated, it said.
Once inside Twitter’s internal systems, the hackers were not able to see users‘ previous passwords but could access personal information including email addresses and phone numbers as these are visible to staff using internal support tools.
They may also have been able to view additional information, the company said.
