Radiant Capital suffers flash loan attack, loses $4.5 million

RadiantCapital suffered a lightning loan attack and lost $4.5 million. The attacker manipulated the index parameter (later used as the denominator) to become very large. There was a rounding error in the calculation of the contract, which resulted in accumulated precision errors. As the index parameter rapidly expanded, this precision error was also amplified, ultimately allowing the attacker to profit through repeated deposit() and withdrawal() operations.