Twitter accounts belonging to Joe Biden, Bill Gates, Elon Musk and Apple, among other prominent handles, were compromised on Wednesday.
It was all a scam, of course, the result of one of the most brazen online attacks in memory.
A first wave of attacks hit the Twitter accounts of prominent cryptocurrency leaders and companies. But soon after, the list of victims broadened to include a Who’s Who of Americans in politics, entertainment and tech, in a major show of force by the hackers.
Twitter quickly removed many of the messages, but in some cases similar tweets were sent again from the same accounts, suggesting that Twitter was powerless to regain control.
The company eventually disabled broad swaths of its service, including the ability of verified users to tweet, for a couple of hours as it scrambled to prevent the scam from spreading further. The company sent a tweet saying that it was investigating the problem and looking for a fix. “You may be unable to Tweet or reset your password while we review and address this incident,” the company said in a second tweet. Service was restored around 8:30 Wednesday night.
Twitter’s investigation into the breach revealed that several employees who had access to internal systems had their accounts compromised in a “coordinated social engineering attack,” a spokesman said, referring to attacks that trick people into giving up their credentials. The attackers then used Twitter’s internal systems to tweet from high-profile accounts like Mr. Biden’s.
“We’re looking into what other malicious activity they may have conducted or information they may have accessed,” Twitter’s spokesman added. “We’ve taken significant steps to limit access to internal systems and tools while our investigation is ongoing.”
Jack Dorsey, Twitter’s chief executive, said in a post Wednesday night that it was a “tough day for us at Twitter. We all feel terrible this happened. We’re diagnosing and will share everything we can when we have a more complete understanding of exactly what happened.”
The hackers did not use their access to take aim at any important institutions or infrastructure — instead just asking for Bitcoin. But the attack was concerning to security experts because it suggested that the hackers could have easily caused much more havoc.
There was little immediate evidence for who conducted the attack. One of the most obvious culprits for an attack of this scale, North Korea, has been documented to have used Bitcoin extensively in the past. But its nature — “effective, but also amateurish” in the words of one senior American intelligence official — led American intelligence agencies to an initial assessment that this was most likely the work of an individual hacker, not a state.
Had it been Russia, China, North Korea or Iran, said the official, who would not speak on the record because they were not authorized to discuss an intelligence investigation, the effort would have probably focused on trying to trigger stock market havoc, or perhaps the issuance of political pronouncements in the name of Mr. Biden or other targets.
Officials also noted that the breach did not affect the account of one of the most watched and powerful users of Twitter: President Trump. Mr. Trump’s account is under a special kind of lock-and-key after past incidents, the official noted.
Security experts said that the wide-ranging attacks hinted that the problem was caused by a security flaw in Twitter’s service, not by lax security measures used by the people who were targeted. Alex Stamos, director of the Stanford Internet Observatory and the former chief security officer at Facebook, said there were a range of other theories, but all suggested that the attackers got inside Twitter’s system, rather than stealing the passwords of individual users.
One American official called that a “scary possibility” in a world where national leaders, sometimes imitating Mr. Trump’s techniques, have adopted Twitter as a primary source of unfiltered communications.
“It could have been much worse. We got lucky that this is what they decided to do with their power,” Mr. Stamos said.
The hacker or hackers made some rookie errors. Mr. Stamos said that because the attackers had sent identical messages from the compromised accounts, they were easy to detect and delete. The decision to ask for money through Bitcoin, he added, showed that the attackers were most likely unable or unwilling to launder money or use their access for a more sophisticated scam.
The messages were a version of a long-running scam in which hackers pose as public figures on Twitter, and promise to match or even triple any funds that are sent to their Bitcoin wallets. But the attacks Wednesday were the first time that the real accounts of public figures were used in such a scam.
Bitcoin is a popular vehicle for this type of scam because once a victim sends money, the design of Bitcoin, with no institution in charge, makes it essentially impossible to recover the funds.
By Wednesday evening, the Bitcoin wallets promoted in the tweets had received over 300 transactions and Bitcoin worth over $100,000, according to websites that track Bitcoin’s public ledger of transactions, which is known as the blockchain.