Hacker turns 25 cents into 46 billion fake Bitcoins to steal $770,000 — Symbiosis DeFi exchange bit by lack of basic bounds checking in smart contract

Symbiosis is one of the many useful DeFi networks that let users trade across almost any crypto pair without having to talk to an exchange. It's been operating for five years, and links some 50-odd chains together. The ecosystem's reliance purely on smart contracts (code that's hosted on the blockchain, visible to anyone) is fully logical but paradoxically creates an accountability problem. This was demonstrated on September 11, when Symbiosis got hacked to the tune of at least $770,000, or 9.97 BTC.Smart contracts are published on the blockchains themselves and are open-source by definition. This means anyone can find a bug, and Symbiosis' thief found two: an undisclosed privilege escalation exploit that let them fake network administrator privileges, plus a Coding-101 failure of not checking if a transaction fee was a positive number.Get Tom's Hardware's best news and in-depth reviews, straight to your inbox.