The FBI is warning attendees and businesses at the Beijing Winter Olympics to be wary of the cybersecurity risks that they should be protecting against. This warning comes only three days before the opening ceremony.

In a bulletin shared by the FBI’s Cyber Division on Tuesday, the bureau detailed the "broad range" of cyber activities that visitors should be mindful of in the Chinese capital. These threats include data theft, ransomware and phishing attempts that come with any major event, but the FBI warns that the games are likely to attract significantly more effort from hackers and nation-states alike.

“[Large] high-profile events provide an opportunity for criminal and nation-state cyber actors to make money, sow confusion, increase their notoriety, discredit adversaries, and advance ideological goals,” according to the FBI.

The Games are likely to be limited in terms of attendance because of China’s stringent COVID-19 policies meant to keep the games on track. The FBI cautioned that the expected emphasis on online streaming and social media to make up for this can act as a draw to opportunistic cyber actors.

For example, the FBI pointed to experiences at past games to underscore the seriousness of the threat. The most recent Summer Olympics in Tokyo saw more than 450 million attempted cyber-related incidents, according to the NTT Corporation which provided its services for the games. During the last Winter Olympics in 2018 in PyeongChang, South Korea, Russian hackers managed to disrupt the opening ceremony with a massive cyber attack. U.S officials later told the Washington Post that the hacking was done by Russian military intelligence in an operation designed to direct the blame to North Korea.

What makes the Olympics more of a target-rich environment for cyber actors is the presence of high-profile delegations and large businesses that it attracts. In the case of the U.S., the Biden administration has refused to send a diplomatic delegation for the opening ceremony in protest of China’s treatment of its Uyghur Muslim minorities.

However, U.S. sponsors for major brands and other businesses are still going to be in Beijing, which can put them at risk of a cyber attack. To mitigate their risks, the FBI encouraged companies to begin training personnel on how to detect attacks on their networks and to prepare business continuity plans if they experience a breach.

The FBI also urged athletes to be careful when using a mobile app mandated by the Chinese authorities called "My 2022." Ahead of the games, experts told the Wall Street Journal that the app is riddled with flaws that left athletes’ data at risk by failing to encrypt their data or authenticate the identity of users trying to access them.

The Beijing Olympic Committee denied this and said reports of the apps' faults were “lacking in facts and evidence."