EvilReflex: Exploiting the approveAndCallcode Vulnerability in Globalvillage Ecosystem (GVE) Smart Contract

CVE-2018-12702

The approveAndCallcode function of a smart contract implementation for Globalvillage ecosystem (GVE), an Ethereum ERC20 token, allows attackers to steal assets (e.g., transfer the contract's balances into their account) because the callcode (i.e., _spender.call(_extraData)) is not verified, aka the "evilReflex" issue. NOTE: a PeckShield disclosure states "some researchers have independently discussed the mechanism of such vulnerability."

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