CVE-2018-13675 in YAMBYO
Summary
by MITRE
The mintToken function of a smart contract implementation for YAMBYO, an Ethereum token, has an integer overflow that allows the owner of the contract to set the balance of an arbitrary user to any value.
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Analysis
by VulDB Data Team • 02/28/2020
The vulnerability identified in CVE-2018-13675 represents a critical integer overflow flaw within the mintToken function of the YAMBYO Ethereum token smart contract implementation. This vulnerability stems from inadequate input validation and arithmetic operation handling within the smart contract code, specifically affecting the token's issuance mechanism. The flaw allows the contract owner to manipulate user balances through controlled integer overflow conditions, creating a fundamental security breach in the token's access control and distribution system.
The technical execution of this vulnerability occurs through the mintToken function's improper handling of integer arithmetic operations. When the contract owner invokes this function with specific parameters, the integer overflow condition is triggered, enabling manipulation of the target user's balance to any desired value. This represents a classic integer overflow vulnerability classified under CWE-190, which deals with integer overflow and wraparound conditions. The flaw exploits the fundamental nature of integer arithmetic in smart contracts where operations exceeding maximum value limits can wrap around to produce unexpected results, allowing attackers to bypass normal balance limitations.
The operational impact of this vulnerability extends beyond simple balance manipulation, as it fundamentally compromises the integrity of the token economy and user trust. An attacker with owner privileges can inflate or deflate user balances arbitrarily, potentially leading to massive financial losses for token holders and undermining the entire token's value proposition. The vulnerability creates a persistent backdoor that remains active until the contract is patched, as the integer overflow condition can be repeatedly exploited with different parameters. This type of vulnerability aligns with ATT&CK technique T1548.001, which covers abuse of credentials and privilege escalation, as the contract owner can leverage their position to gain unauthorized control over user assets.
Mitigation strategies for this vulnerability require immediate patching of the smart contract code to implement proper integer overflow protections. The solution involves adding explicit bounds checking and using safe arithmetic libraries such as OpenZeppelin's SafeMath implementation to prevent overflow conditions. Additionally, the contract should undergo comprehensive security auditing to identify similar patterns throughout the codebase, as integer overflows often occur in multiple functions. The remediation process should also include implementing proper access controls and ensuring that only authorized entities can invoke mintToken functions. Regular security assessments and formal verification of smart contract code should become standard practices to prevent similar vulnerabilities from emerging in future implementations. Organizations should also consider implementing multi-signature wallets and time locks for critical contract functions to add additional layers of security and reduce the attack surface.