The world of crypto isn't just suffering from a market malaise that has seen the price of bitcoin drop from $69,000 to around $20,000 today—it also faces a troubling number of security risks.

There have been dozens of breaches in the past few years, showing that cyber-criminals are gravitating toward the world of cryptocurrencies. In many cases, we don't know who the attackers are, but one culprit that keeps coming up is the band of state-backed hackers from North Korea known as the Lazarus Group.

According to a new book by Geoff White, "The Lazarus Heist," the regime's hackers have become increasingly sophisticated over the past decade, managing to steal an estimated US$2 billion worth of cryptocurrency to date. Crypto investors should expect the gang to continue exploiting blockchain targets, or the "the soft underbelly of the financial system," according to White, who believes the $2 billion figure is a "vast underestimate."