The World Anti-Doping Agency (WADA) said on Wednesday that some of the athlete data leaked by a Russian cyber espionage group has been changed from its initial form, and has asked "affected parties" for feedback on any inaccuracies.
Since the hacking group first released confidential medical data on Sept. 13, it has released five more batches involving athletes from countries including the United States, Germany, Britain, Poland and Denmark who competed at the Rio Olympics.
The hacking group, known as APT28 and Fancy Bear by U.S. cyber-security researchers, has posted data about athletes such as U.S. gymnast Simone Biles, U.S. tennis players Serena and Venus Williams and England's Olympic golf champion Justin Rose.
WADA said the hackers gained access to its anti-doping administration and management system (ADAMS) via an IOC-created account for the Rio Games, which has since been secured and investigated by a premier security and forensic consulting firm.
According to WADA, the account included confidential medical data such as Therapeutic Use Exemptions, which are issued by sports federations and national anti-doping organizations to allow athletes to take certain substances.
"As of Oct. 5 ... analysis is over 90 percent complete, and it has not found any evidence of additional compromise to ADAMS data beyond the export of the Rio 2016 ADAMS Account data through 12 September, as described above," WADA said.
"It should also be noted that in the course of its investigation, WADA has determined that not all data released by Fancy Bear (in its PDF documents) accurately reflects ADAMS data.
"However, we are continuing to examine the extent of this as a priority and we would encourage any affected parties to contact WADA should they become aware of any inaccuracies in the data that has been released."
WADA has reached out to the national anti-doping organisations and international federations whose athletes have been impacted by the data releases to provide support.
WADA, which believes the attacks were carried out as retaliation for the agency's investigations that exposed state-sponsored doping in Russia, said it would continue to provide relevant updates as circumstances evolve.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)