CVE-2018-13659

Vulnerability

The BrianCoin Ethereum token contract (all versions) contains an integer overflow vulnerability in the mintToken function. The function performs arithmetic operations without proper overflow checks, enabling the contract owner to mint an arbitrary number of tokens to any address. This pattern is similar to other vulnerable token contracts described in [1]. The vulnerable code can be found in the BrianCoin repository [2].

Exploitation

An attacker must be the contract owner to exploit this vulnerability. The owner calls mintToken with a large value parameter that, when added to the current total supply or recipient balance, causes an integer overflow. Due to the overflow, the resulting balance becomes an arbitrary small or large value, as controlled by the attacker.

Impact

Successful exploitation allows the owner to set the balance of any user to any value, effectively manipulating the token supply and individual balances. This can lead to financial loss for token holders, undermine the token's value, and enable theft or price manipulation.

Mitigation

No fixed version has been released for BrianCoin. The vulnerability can be prevented by using SafeMath library functions (e.g., add with require) to handle arithmetic safely, as recommended in [1]. Token holders should exercise caution when interacting with this contract, as no patch is available.