Who was behind the hijacking of a Twitter celebrity account?

Twitter this week suffered a potentially far-reaching massive hacking attack in which unknown attackers hijacked the official accounts of celebrity executive politicians, well-known companies and digital currency trading platforms, fraudulently sending bitcoins to their wallet addresses. The first signal of the invasion was that The Exchange-Currency ansaid that it would participate in the CryptoForHealth campaign to give back to the community 5000 BTC. Other celebrity accounts then began posting similar posts.

Security blog KrebsOnSecurity reports that there are many indications that the attackers behind the attack were those who had previously been ademyteitus in using SIM swapping to hijack social media accounts.

At OGuser, a forum devoted to account hijacking, a user named Chaewon advertised that spending $250 could change the email address of any Twitter account before the massive attack. Chaewon guarantees a full refund if it is invalid.

KrebsOn Security quoted sources as saying the infamous SIM swapper used the pseudonym PlugWalkJoe, whose real identity is Joseph James Connor, a 21-year-old Liverpool native. He is now in Spain and cannot return home because of the outbreak.                   

Who was behind the hijacking of a Twitter celebrity account?