One of the 12 largest DeFi, Crypto hacks. My summary here: https://crypto.security/crypto-blockchain-security/kucoin-hack/
KuCoin is a Singapore-based crypto exchange that consistently ranks among the top 5 exchanges in terms of daily volume serving the crypto markets in Asia. On September 25, 2020, KuCoin suffered one of the biggest crypto hacks. More than 150 different cryptocurrencies made up the loot, which were valued at roughly $285M at the time.
We would later learn that their private keys had been leaked. Without multisig security enabled, attackers were able to drain the wallets without facing any resistance.