Image copyright AP Image caption Simone Biles' confidential medical data has been released 
 
 The World Anti-Doping Agency (Wada) has condemned Russian hackers for leaking confidential medical files of star US Olympic athletes. 
 
 Athletes affected include tennis players Venus and Serena Williams and teenage gymnast Simone Biles. 
 
 A group calling itself "Fancy Bears" claimed responsibility for the hack of a Wada database. 
 
 After the leak, Ms Biles said she had long been taking medicine for Attention Deficit Hyperactivity Disorder. 
 
 The hacker group had accused her of taking an "illicit psycho-stimulant", but she said she had "always followed the rules". 
 
 The Rio Olympics quadruple gold medallist had obtained the necessary permission to take prescription medicine on the Wada banned drugs list, USA Gymnastics said in a statement. 
 
 Image copyright @Simone_Biles 
 
 Wada said in a statement that the cyber attacks were an attempt to undermine the global anti-doping system. 
 
 Russian government spokesman Dmitry Peskov said it was "out of the question" that the Kremlin or secret services were involved in the hacking, Russian news agencies reported. 
 
 The hackers accessed records detailing "Therapeutic Use Exemptions" (TUEs), which allow the use of banned substances due to athletes' verified medical needs. 
 
 "By virtue of the TUE, Biles has not broken any drug-testing regulations, including at the Olympic Games in Rio," USA Gymnastics said. 
 
 Fancy Bears said TUEs amount to "licences for doping". 
 
 The leaked documents allege that Serena Williams was granted permission to use drugs commonly used to treat muscle injuries, such as anti-inflammatories, while Biles is said to use Ritalin - a treatment for her ADHD. 
 
 Former - Australian Sports Anti-Doping Authority head Richard Ings said: "Nothing I see here gives me cause for alarm," adding it looked "totally normal". 
 
 "The issue here is privacy breach." 
 
 'Compromising trust' 
 
 Russia's track and field team were banned from the Rio Olympics over an alleged state-backed doping programme. All of its athletes are barred from the ongoing Paralympics. 
 
 "Let it be known that these criminal acts are greatly compromising the effort by the global anti-doping community to re-establish trust in Russia," Wada director-general Olivier Niggli said. 
 
 'An act of revenge?' - Analysis by BBC sports editor Dan Roan 
 
 This is the latest twist in what was already the biggest doping scandal in the history of sport, and further evidence of the bitter divisions it has sparked. 
 
 The hack appears to be an act of revenge - retaliation for Wada's damning report into Russian state-sponsored cheating. 
 
 Although the Russian government has denied any involvement, it has always maintained that the country has been made a scapegoat for a much wider problem, and this will only add fuel to that fire. 
 
 Although the athletes concerned have broken no rules, the revelations - along with the threat of more leaks of other competitors' medical records - will inevitably exacerbate the controversy surrounding TUEs at a time when sport's leaders are desperately trying to restore trust. 
 
 Many athletes will now be nervously wondering if their private medical details records are the next to be made public. 
 
 And with the future of Wada currently in the balance, the fact its security was so badly compromised will raise more questions over the entire anti-doping system, especially after the account of Russian whistleblower Yuliya Stepanova was hacked last month, leading to fears for her safety. 
 
 US Anti-Doping Agency chief Travis Tygart called the hack "cowardly and despicable". 
 
 "In each of the situations, the athlete has done everything right in adhering to the global rules for obtaining permission to use a needed medication," he said. 
 
 Image copyright PA Image caption Serena Williams has won four Olympics golds in her career 
 
 The US Olympic Committee has had "zero adverse findings from the Rio Olympic Games that weren't 100% within the medical guidelines set forth by anti-doping authorities," spokesman Patrick Sandusky said. 
 
 Earlier this month, Mr Niggli said Wada was experiencing almost daily cyber attacks originating from Russia. 
 
 Fancy Bears, which is also known as Tsar Team (APT28), has pledged to release confidential records from other national Olympic teams. 
 
 How Wada was hacked - Dave Lee, BBC North America technology reporter 
 
 Image copyright Reuters 
 
 It's an old adage in cybersecurity that the weakest point of any supposedly secure system is the people that use it. 
 
 Wada says it believes this hack was made possible thanks to a successful spearphishing attack. Phishing is a term given to the technique of tricking a user into giving up crucial information - often by clicking a link that takes them to a malicious website disguised as a familiar one, such as the log-in page for a bank or social network. 
 
 Spearphishing takes this one significant step further. While a phishing attack is often aimed at many people in the hope some will fall for it, spearphishing is highly targeted. Hackers perhaps identified a small number of people, or even just one person, and wrote a phishing attack specifically designed to trick them. 
 
 Other than pushing a message of vigilance among staff, spearphishing is incredibly difficult to defend against. Attackers often scour the internet, looking for added information on the target that might make an email more believable. Sometimes even knowing a person's favourite football team is enough to tip the balance in making a spearphishing email seem genuine. ||||| The World Anti-Doping Agency said Tuesday that a Russian government hacking group had gained access to a database containing drug-test results and confidential medical data from last month’s Olympics in Rio de Janeiro. On Monday, the group began posting confidential information about noteworthy U.S. Olympic athletes — tennis stars Serena and Venus Williams, four-time gymnastics gold medalist Simone Biles and women’s basketball standout Elena Delle Donne — and promised more leaks would be forthcoming. 
 
 WADA said in a statement that the hacking group was able to access passwords to its Rio Olympic database via spear-phishing, the practice by which computers are infected after a user opens an email that is thought to be from a trusted source. 
 
 “WADA deeply regrets this situation and is very conscious of the threat that it represents to athletes whose confidential information has been divulged through this criminal act,” Director General Olivier Niggli said in the statement. “We are reaching out to stakeholders … regarding the specific athletes impacted.” 
 
 The data release comes as the FBI is conducting a broad investigation into Russian government hacking and influence operations in the United States, including a possible effort to undermine confidence in the U.S. elections. The latest incident appears to be part of a larger campaign of strategic releases of hacked material by the Russian government to embarrass victims or raise doubts about their integrity, analysts said. 
 
 It comes after nearly every member of that country’s track and field team was banned from this year’s Olympics after numerous investigations uncovered a widespread, government-run doping scheme that dated back years. 
 
 “They’re trying to sow doubt over the integrity of the individual athletes and the various Olympic bodies and watchdog groups,” said Rich Barger, chief information officer at ThreatConnect, a cybersecurity company. “It’s just ultimately sour grapes. What we’re seeing here is a digital temper tantrum.” 
 
 The information released mostly involves Therapeutic Use Exemptions, situations in which WADA allows athletes to take certain banned substances if they’re used to treat legitimate medical issues. 
 
 In a statement to Newsweek, the International Olympic Committee said none of the athletes mentioned in the hack had done anything wrong. 
 
 “The IOC strongly condemns such methods which clearly aim at tarnishing the reputation of clean athletes,” the organization said. “The IOC can confirm, however, that the athletes mentioned did not violate any anti-doping rules during the Olympic Games Rio 2016.” 
 
 The hacking group, which is known as Fancy Bear or APT28, works for the military intelligence service GRU. It was one of two Russian spy groups that hacked the Democratic National Committee and may be linked to the release of embarrassing DNC emails by WikiLeaks in July. It has also been active in propaganda operations, researchers say. And last year it hacked the French TV5Monde station, knocking the network off the air for 18 hours in April 2015. 
 
 In its statement, WADA said one of the victims whose password was stolen was Yuliya Stepanova, a whistleblower who exposed widespread doping in Russia athletics. 
 
 “We will start with the U.S. team which has disgraced its name by tainted victories,” the group said on a website that exposed the hacked WADA documents. “We will also disclose exclusive information about other national Olympic teams later. Wait for sensational proof of famous athletes taking doping substances any time soon.” ||||| The World Anti-Doping Agency (Wada) has announced that its database was accessed by a Russian hacking group, which posted the confidential medical data of several US athletes online on Monday. 
 
 The cyber espionage group, known as Fancy Bear, released records on four female American Olympic athletes: tennis stars Serena and Venus Williams, gymnastics multi-gold medallist Simone Biles and basketball player Elena Delle Donne. 
 
 In each case, the hackers published records of so-called “Therapeutic Use Exemptions”, which permit athletes to use certain otherwise banned substances if they have a verified medical reason to do so. In making the disclosure, Fancy Bear said it planned to release more information in due course. 
 
 The group, also known as Tsar Team, claimed the Therapeutic Use Exemptions constituted evidence of doping by US Olympians. “After detailed studying of the hacked Wada databases we figured out that dozens of American athletes had tested positive,” the hackers said in a statement. “The Rio Olympic medallists regularly used illicit strong drugs justified by certificates of approval for therapeutic use. In other words, they just got their licences for doping.” 
 
 US Anti-Doping Agency (Usada) chief Travis Tygart said in a statement that it was “unthinkable” for hackers to “illegally obtain confidential medical information in an attempt to smear athletes to make it look as if they have done something wrong.” He added: “In fact, in each of the situations, the athlete has done everything right in adhering to the global rules for obtaining permission to use a needed medication.” 
 
 Wada Report Outlines Alleged Russian Doping Cover Up System Used in Sochi 
 
 Wada had previously warned that it might face cyberattacks, following its investigators’ revelations of Russian state-sponsored doping in the run-up to the Rio Games this summer. “These criminal acts are greatly compromising the effort by the global anti-doping community to re-establish trust in Russia,” said Olivier Niggli, the agency’s director general. “Wada deeply regrets this situation and is very conscious of the threat that it represents to athletes whose confidential information has been divulged.” 
 
 The agency said it believed the hack was carried out using spear-phishing emails to gather passwords for the Wada Anti-Doping Administration and Management System (Adams) database. Less than a month ago, the agency confirmed that a hacker had accessed the Adams account for Yuliya Stepanova, the Russian 800-metre runner who blew the whistle on the widespread doping among her country’s Olympic team. 
 
 More than 100 Russian athletes were subsequently banned from competing in Rio, following the publication of an independently commissioned Wada report, which found evidence of a Russian state-run doping programme going back at least four years. ||||| Russian hackers — possibly the same group that compromised the Democratic National Committee’s computer servers — have made top American athletes their latest target. 
 
 Joining an intercontinental dispute over sports doping, the hackers penetrated the World Anti-Doping Agency’s athlete database and publicly revealed private medical information about three of the United States’ most famous athletes: Serena Williams, Venus Williams and Simone Biles. 
 
 The hackers published documents this week showing that Ms. Biles, who won four gold medals in gymnastics at the Rio Olympics last month, and the Williams sisters received medical exemptions to use banned drugs. 
 
 The antidoping agency confirmed the authenticity of the documents in a statement Tuesday, attributing the hack to Fancy Bear, a Russian cyberespionage group that forensics specialists have tied to breaches against government agencies, nonprofit organizations and corporations. That group is believed to be associated with G.R.U., the Russian military intelligence agency suspected of involvement in the recent theft of emails and documents from the D.N.C.
– In what one analyst calls a "digital temper tantrum," hackers linked to the Russian government have hacked into the World Anti-Doping Agency's Olympic database and released information on star American athletes, including Serena and Venus Williams. WADA has confirmed the security breach, and the hacking group "Fancy Bears"—which was apparently motivated by revenge for WADA's exposure of state-sponsored Russian doping—says there are more leaks to come, the Washington Post reports. A roundup of developments: Fancy Bears also posted information on gymnast Simone Biles and basketball player Elena Delle Donne relating to "Therapeutic Use Exemptions" that allow athletes to use banned substances for valid medical reasons, the Independent reports. The hackers claimed the exemptions were "licenses for doping." WADA says it believes the attacks were carried out with a "spear-phishing" attack that gathered passwords with emails to authorized users that convinced them to click on infected links. According to the leaked documents, Biles uses medication to treat ADHD. "Having ADHD, and taking medicine for it is nothing to be ashamed of" and "nothing that I'm afraid to let people know," she tweeted in response. Venus Williams, who was diagnosed with the autoimmune disease Sjogren's syndrome in 2011, issued a statement saying she followed all the rules and was disappointed "that my private, medical data has been compromised by hackers and published without my permission." The Fancy Bears group is believed to be linked to the Russian military intelligence agency suspected of hacking the DNC, reports the New York Times, which notes that the Kremlin "has gone to to great lengths to maintain plausible deniability in matters of espionage"—and denies involvement in the WADA hack. The hackers are "trying to sow doubt over the integrity of the individual athletes and the various Olympic bodies and watchdog groups," Rich Barger of cybersecurity firm ThreatConnect tells the Post. "It's just ultimately sour grapes. What we're seeing here is a digital temper tantrum." US Anti-Doping Agency chief Travis Tygart called the hack "cowardly and despicable," saying that the athletes involved had "done everything right in adhering to the global rules for obtaining permission to use a needed medication," the BBC reports. Fancy Bears, which claims to be allied with Anonymous, says it will release information on other countries' athletes this week, reports the AP, which found that a French phone number provided by the group was bogus and the mailing address it gave was that of a florist east of Paris.