The latest report from blockchain security company Halborn reveals that despite a decrease in the total amount of funds stolen in 2023, hack attacks in the decentralized finance (DeFi) sector remain a significant security threat. The report meticulously analyzes 100 of the largest DeFi hack incidents between 2016 and 2023, involving a total of $7.4 billion. During this period, Ethereum, Binance Smart Chain, and Polygon were hit hardest by hacker attacks. The report points out that although on-chain attacks, such as smart contract vulnerabilities, price manipulation, and governance attacks, are common, off-chain attacks, particularly key theft, accounted for 29% of all attacks and led to 34.6% of the losses. Notably, in 2023, off-chain attacks made up 56.5% of total attacks, with their share of stolen funds reaching 57.5%. The report also highlights that only 21% of hacked protocols used multi-signature wallets, and most on-chain attacks occurred on unaudited protocols, with errors in input validation or confirmation mechanisms within the protocol being the main cause of smart contract exploitation. Furthermore, cross-chain bridges continue to be the main route for hackers to conduct attacks.