In one of the Starbucks cafes in Buenos Aires, a client who is the director of a technology company found a hacker code connected to his laptop for hidden cryptocurrency mining. As a result of the investigation, it turned out that a local provider traded through underground mining via Wi-Fi. An angry cafe visitor who received not entirely free Wi-Fi turned to Twitter visitors. He indicated a 10 second delay before connecting to a Wi-Fi network. In addition, the malicious code CoinHive, designed to mine Monero cryptocurrency, appeared on the laptop. Representatives of Starbucks quickly responded to the remark of Noah Dinkin, the same client who discovered the ill-fated script installed by attackers usually in websites for mining digital currency Monero due to the power of PC visitors to the resource. The local provider turned out to be the fault, with which the owners of the coffee shop quickly dealt with. Thus, in hidden mining, the provider of public wireless Internet was found guilty. As soon as we were alerted of the situation in this specific store last week, we took swift action to ensure our internet provider resolved the issue and made the changes needed in order to ensure our customers could use Wi-Fi in our store safely.— Starbucks Coffee (@Starbucks) December 11, 2017. However, this incident indicates the danger of using public wireless Internet networks. While this is only illegal use of a computer for mining, however, cunning attackers are always inventive and can do much more harm, for example, by stealing confidential data or passwords.