DeFi combines conventional blockchain-related strategies like smart contracts, digital assets, wallets, and oracle-based auxiliary services to construct a successful financial system. DeFi utilizes numerous types of cryptographic keys, which are cardinal to the DeFi system. Albeit the cryptography keys provide fundamental security to the DeFi system, the storage of private keys and maintenance lead to several hacking activities. Moreover, apart from the financial freedoms of the DeFi system, it is vulnerable to some risks, as follows.
   •  Immature DeFi Models
   •  Lacking to protect the Consumers
   •  High Hacking Vulnerabilities
   •  High Collateral Requirements
   •  Requirement of Private Keys
  Some of the DeFi attacks are defined as follows.
   •  51% Attack
   •  Smart Contract Attack
   •  Double-Spending Attack
   •  Phishing Attack
   •  Oracle Attack
   •  Double-Claiming Attack
   •  Reentry Attack
   •  Private Key Leakage Attack