VIENNA — Austrian police say cyber thieves transferred Bitcoins worth more than 100,000 euros, or $117,000, from a man's account while he was logged in on a restaurant's public wireless network.

A police statement Wednesday says the Bitcoins were moved to an "unknown, non-traceable account" after the unidentified 36-year old logged in southeast of the city of Innsbruck on Tuesday to check the value of his digital currency.

It remains unclear whether the victim's account was already hacked before he logged on to the unsecured network, the police statement reported.

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Cryptocurrencies like Bitcoin and Ethereum have long been dogged by concerns about their security, particularly after the collapse of the Bitcoin exchange Mt. Gox in 2014. The company's former CEO, Mark Karpales, is currently on trial in Japan, where the corporation was based, on embezzlement and data manipulation charges. Karpales has blamed the company's collapse on hackers.

South Korea's largest Ethereum and Bitcoin exchange was breached in late June in a theft estimated at 1.2 billion won, or a little over $1 million. A Pennsylvania man also recently confessed to stealing $40 million worth of Bitcoin.

Despite the risks, investors continue to have faith in digital currencies even as their prices fluctuate wildly. Ethereum, which started the year valued at $8.17, has in a matter of months soared 2,600 percent. Over the same period, Bitcoin prices have surged from $1,027 to more than $8,000 -- with many stunning price collapses on the roller coaster ride up.

Bitcoin, the largest cryptocurrency by market value, on Tuesday climbed as high as $8,339 in New York trading -- a new record. This happened despite earlier Bitcoin losses in the day of around 5 percent after news emerged of a $31 million theft of a cryptocurrency cousin called Tether.

Ethereumm -- which has emerged from the shadow of its better-known rival Bitcoin thanks to ithe latter's skyrocketing price -- also has become a tempting target for hackers.

Thieves in July stole $10 million from an electronic wallet provide by Coindash, a company that specializes in the kind of blockchain technology used in digital currencies. Another $32 million recently went missing after hackers exploited a vulnerability in an e-wallet from startup Parity.

The price of Ethereum slumped following news of the heists, tumbling more than 15 percent from $258.52 in mid-July to $218.82 days later, according to CoinMarket Cap.

New investors in Ethereum may not be aware of the risks of losing their funds to hackers, said Simon Yu, CEO of StormX. The company, formerly called CakeCodes, offers cryptocurrency rewards to computer game players. He said accounts should be secured with private keys whose combinations are known only to the account holders.