CVE-2018-13468

Vulnerability

The mintToken function in the Cavecoin Ethereum token smart contract contains an integer overflow vulnerability. The function does not use SafeMath or perform overflow checks when updating a user's balance. This allows the contract owner to call mintToken with a large mintedAmount value, causing an integer overflow that sets the target user's balance to an arbitrary value. The affected contract is the Cavecoin token implementation as found in the referenced repository [1][2]. All versions of this contract are vulnerable.

Exploitation

An attacker must be the contract owner (the address that deployed the contract). The owner calls mintToken with a target address and a mintedAmount value that, when added to the target's current balance, exceeds the maximum uint256 value, causing an overflow. The overflow results in the target's balance being set to a low or zero value, or any value the attacker chooses by carefully selecting the overflow amount. No user interaction is required beyond the owner's transaction [1][2].

Impact

A successful exploit allows the contract owner to arbitrarily set the balance of any user to any value. This can be used to inflate the total token supply, drain tokens from other users, or manipulate the token's perceived value. The impact is a complete loss of token integrity and potential financial loss for holders [1][2].

Mitigation

No official fix or patched version has been published for Cavecoin in the available references. The vulnerability can be mitigated by using SafeMath library functions (e.g., add and sub) to prevent integer overflows, or by implementing explicit overflow checks in the mintToken function. As of the publication date (2018-07-09), the contract remains unpatched [1][2].