51% Attacks: 51% attacks are one of the most well-known blokchain security issues. In the 51% attack, one or more malicious entities control the majority of the hashrate of a blockchain. They can reverse the process to make double spending with the majority hashrate and to prevent other miners from approving the blocks.
In 2018, many important crypto currencies, such as ZenCash, Verge and Ethereum Classic, were attacked by 51%. In general, the attackers exploited this blockchain security problem and earned more than $ 20 million last year.
Stock Market Attacks: One of the most expensive block chain security issues is not a problem in the block chain technology itself. Crypto money exchanges have become a profitable area for hackers because of their huge crypto usage and sometimes weak security practices. Since many exchange platforms are centrally centralized, they restore the decentralized benefits of the blockchain.
Any early crypto buyer can tell you about the 2014 Mt Gox hack. Mt. Gox was the stock market leader of the time and managed almost 70 percent of all bitcoin transactions. In February 2014, the stock market revealed that a hacker stole around 850,000 BTC (~ $ 473 million) from the platform. The affected users were left behind.
Social Engineering: Another blockchain security issue that you and your employees should know is social engineering. Social engineering comes in many forms, but the goal is always the same: to obtain your private keys, login information or more directly in your crypto currency.
Phishing: Phishing is one of the most common forms of social engineering. In an attempt to fake, a malicious player sends you emails, sends messages, and even creates a website or social media account that mimics a company brand you trust. Typically, they will ask you to submit your credentials under a gift or a critical issue to enforce a sense of urgency. If you submit your information, there is very little you can do to prevent them from deleting your account.