On February 21, 2025, a serious security incident occurred at the cryptocurrency exchange Bybit, where over $1.5 billion in assets were stolen. This incident is similar to the attack on the Radiant Capital cross-chain lending protocol in October 2025, where attackers stole funds by controlling multi-signature private keys and exploiting contract vulnerabilities. Both incidents highlight the increasing complexity of hacker attacks and expose security vulnerabilities in the crypto industry. This article provides an in-depth analysis of the technical details of the Radiant incident, focusing on the abuse of malicious contracts and multi-signature wallets. The article concludes by emphasizing the urgent need to strengthen industry security measures to protect user assets.