Experts are warning about a potential uptick in cyber crime activity in connection with the 2016 Olympic Games in Rio de Janeiro as high-tech criminals gear up for the large crowds of wealthy tourists expected at the event.

A report published August 2 by the cyber security firm Fortinet said that several indicators point to increasing cyber crime activity in Brazil ahead of the Olympics, including an 83 percent bump in the volume of malicious URL addresses created during the month of June.

A June report from researchers at Kaspersky Lab, another cyber security firm, noted a similar trend. The researchers also pointed out that on-the-ground tests showed roughly one in four wireless internet access points likely to be used by tourists were highly vulnerable to cyber attacks.

Cyber criminals often seek to exploit weak digital security in order to steal personal data like bank account details, which can be used to make fake credit cards.

US officials have been warning for months about cyber crime risks for those planning to attend the Olympics. In February, the State Department’s Overseas Security Advisory Council issued a report describing Brazil as “one of the most pervasive cyber crime environments worldwide.”

In June, Bill Evanina, a top US counter-intelligence official advised travelers not to carry electronic devices with valuable information on them.

“When you travel abroad, assume that your personal information will be breached,” Evanina said, describing international events like the Olympics as a “great playground” for cyber criminals, in part due to the “sheer number of devices.”

Brazilian officials have said they expect between 350,000 to 500,000 foreign tourists to attend the games, which are scheduled to take place from August 5 to August 21.

InSight Crime Analysis

Brazil already loses an estimated $8 billion (pdf) due to cyber crime each year. However, there are indications that cyber crime is not only growing more prevalent in the country, but also more sophisticated.

Brazilian authorities estimated last year that cyber attacks in the country had spiked by nearly 200 percent in 2014 compared with the previous year. And citing a recent report from the computing company IBM, the Financial Times writes that “Brazil’s most prominent cyber crime factions have in the past few weeks acquired a notorious piece of malware dubbed Panda Banker, already used by criminal groups to target banks in North America and Europe.”

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Jens Monrad, an employee of the digital security firm FireEye, recently told the Financial Times that cyber crime groups outside of Brazil are “trying to figure out in-country partnerships or alliances with in-country criminals too.”

It is possible that a potential influx of cash from attacks on Olympic visitors could help Brazilian cyber crime groups obtain other powerful hacking tools, and could further fuel their growth in both numbers and in skill.