A computer hacker is any skilled computer expert that uses their technical knowledge to overcome a problem. While "hacker" technically has a neutral connotation, the term was changed by popular culture, which defines a hacker as someone with technical knowledge who uses bugs or exploits to break into computer systems.
The recent outburst of interest in cryptocurrencies triggered some hackers to begin looking through different crypto exchange services. The latest news on hackers show that no one is protected from their interventions. There were already several cases of exchanges hacks. For example, in January 2018 cryptocurrency exchange service Coincheck was hacked and approximately 500 million NEM tokens were removed from exchange, amounting about $385 million stolen. Although Coincheck was capable to compensate all users with its own capital, there is no confidence that bigger incidents won’t take place.