Cysic Bridge Suspended After $727K Stolen in Token Exploit

An attacker exploited a vulnerability in Cysic's cross-chain bridge to mint 10 million unauthorized CYS tokens on BNB Chain, according to onchain records. The attacker sold 7.2 million of the tokens and bridged the proceeds to Ethereum, amassing about 306.6 ETH, valued at roughly $727,000. Cysic blacklisted the address after the incident, freezing the remaining 2.8 million tokens. The breach occurred on Saturday, with the attacker's activities detected and recorded on blockchain platforms like BscScan and Etherscan. The Cysic Foundation confirmed the exploit involved unauthorized access to a database used by services supporting the bridge, allowing the attacker to submit a fraudulent mint message. The company has suspended the bridge and is working with a security firm to investigate the incident and trace the stolen funds. Cysic emphasized that the breach was limited to the bridge's message-processing and minting functions and did not affect the mainnet. Existing user assets were not stolen, according to the foundation. The company has not disclosed the exact financial loss, noting that the number of tokens minted does not directly translate to a dollar figure. The attacker's actions included multiple transactions across various exchanges, with some routed through OKX’s DEX aggregator. The stolen funds were moved through cross-chain protocols like Mayan, deBridge, and SWFT’s Bridgers, ultimately ending up on Ethereum. The address then transferred the majority of the stolen ETH to a second wallet, which held about 309.5 ETH as of Sunday morning. Cysic will remain closed until a security review is complete and will publish a follow-up report on its findings.