CVE-2018-13836 in Rocket Coin
Summary
by MITRE
An integer overflow vulnerability exists in the function multiTransfer of Rocket Coin (XRC), an Ethereum token smart contract. An attacker could use it to set any user's balance.
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Analysis
by VulDB Data Team • 03/04/2020
The integer overflow vulnerability present in the multiTransfer function of Rocket Coin (XRC) represents a critical security flaw that directly impacts the integrity of the token's accounting system. This vulnerability falls under the CWE-190 category of integer overflow and under the CWE-682 category of incorrect arithmetic, making it a fundamental flaw in the smart contract's mathematical operations. The vulnerability specifically manifests when the contract processes multiple token transfers in a single transaction, where the cumulative calculation of token amounts exceeds the maximum value that can be represented by the integer data type used in the contract.
The technical implementation of this flaw occurs within the multiTransfer function where the contract attempts to calculate the total amount of tokens to be transferred across multiple recipients. When the sum of token amounts approaches or exceeds the maximum value of the integer data type, the arithmetic operation wraps around to zero or negative values due to the overflow behavior. This overflow condition allows an attacker to manipulate the calculation results in ways that can alter user balances arbitrarily. The vulnerability is particularly dangerous because it enables attackers to bypass normal transfer restrictions and potentially drain funds from other users' accounts or inflate their own token holdings.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token ecosystem's trust model. An attacker who successfully exploits this vulnerability could redistribute tokens to their own address while simultaneously reducing other users' balances to zero or negative values, effectively creating a mechanism for unauthorized fund theft. The attack vector requires minimal technical expertise since it exploits the inherent behavior of integer arithmetic in smart contracts rather than requiring complex cryptographic attacks. This makes the vulnerability particularly dangerous as it can be exploited by attackers with basic knowledge of blockchain technology and smart contract interactions.
Mitigation strategies for this vulnerability must address the fundamental mathematical flaw in the contract's implementation. The most effective approach involves implementing proper input validation and overflow checks before performing arithmetic operations, utilizing safe math libraries that automatically handle overflow conditions, or redesigning the multiTransfer function to process transfers individually rather than cumulatively. Organizations should also consider implementing comprehensive testing procedures including formal verification and fuzz testing to identify similar vulnerabilities in smart contract code. The remediation process should follow established security standards such as those outlined in the OWASP Smart Contract Security Verification Standard and should incorporate defensive programming practices that align with the principles of secure blockchain development. Additionally, the vulnerability highlights the importance of thorough code audits and the adoption of security-focused development practices that prevent integer overflow conditions from being introduced into smart contract implementations.