The World Anti-Doping Agency (WADA) said a Russian cyber espionage operator by the name of Tsar Team (APT28), also known as Fancy Bear, successfully hacked the organisation.
Fancy Bear gained access to WADA’s Anti-Doping Administration and Management System (ADAMS) database via an International Olympic Committee-created account for the Rio 2016 Games.
WADA said access to ADAMS was obtained through spear phishing of email accounts.
“ADAMS passwords were obtained enabling access to ADAMS account information confined to the Rio 2016 Games,” said WADA.
The group accessed athlete data, including confidential medical data, and released some of it to the public.
The hacker group threatened to release more data in future.
According to the BBC, the data released affected tennis players Venus and Serena Williams, and gymnast Simone Biles.
Sputnik reported that Serena Williams was allowed to take banned substances – such as oxycodone, hydromorphone, prednisone, and methylprednisolone – in 2010, 2014, and 2015.
Venus Williams was allowed to take prednisone, prednisolone, and triamcinolone, among others, in 2010, 2011, 2012, and 2013.
The report stated that gold medalist Simone Biles tested positive for methylphenidate in August, but was not disqualified.