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 one of the leading theories among researchers was that the hacker, or hackers, had obtained the encryption keys to the system, which enabled them to essentially imitate or steal the “tokens” that grant access to individual accounts.
There were a range of other theories, he said, 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.