CVE-2018-13611 in CDcurrency
Summary
by MITRE
The mintToken function of a smart contract implementation for CDcurrency, 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-2018-13611 represents a critical integer overflow flaw within the mintToken function of the CDcurrency Ethereum token smart contract implementation. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types. The flaw allows an attacker with owner privileges to manipulate token balances by setting them to arbitrary values, effectively bypassing normal token distribution and transfer mechanisms. The integer overflow occurs when the contract performs arithmetic operations without proper bounds checking, enabling malicious actors to exploit the mathematical properties of fixed-size integer representations.
The technical exploitation of this vulnerability leverages the fundamental characteristics of integer arithmetic in smart contract environments where data types have predetermined maximum values. When the mintToken function processes token minting operations, it fails to validate whether the resulting balance would exceed the maximum value that can be represented by the integer type used for balance storage. This creates a scenario where an attacker can craft specific inputs that cause the integer to wrap around to a much smaller value, or in some cases, manipulate the balance to achieve unintended outcomes. The vulnerability directly maps to CWE-190, which describes integer overflow conditions, and specifically aligns with CWE-682, which addresses incorrect arithmetic operations that can lead to unexpected behavior in security-critical contexts.
The operational impact of this vulnerability extends beyond simple balance manipulation and represents a severe threat to the integrity of the token ecosystem. An attacker with owner access can potentially inflate or deflate user balances at will, creating scenarios where users might lose access to their tokens or where malicious actors could accumulate excessive holdings. This flaw undermines the fundamental trust in the token's distribution mechanism and can lead to significant financial losses for token holders. The vulnerability also affects the overall security posture of the Ethereum blockchain deployment, as it demonstrates poor implementation practices that could be exploited in other smart contracts within the same system. The attack surface is particularly concerning because it requires only owner privileges, which are typically limited but still present in many token implementations.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements in smart contract development practices. The primary fix involves implementing proper integer overflow protection mechanisms such as using safe math libraries, adding explicit bounds checking before arithmetic operations, and employing formal verification techniques to validate contract behavior. Organizations should implement comprehensive testing procedures including fuzz testing and symbolic execution to identify similar vulnerabilities in other contract functions. The remediation process should also include code review practices that specifically target integer arithmetic operations and balance management functions. Additionally, the implementation of access control mechanisms and multi-signature requirements for critical functions can reduce the risk associated with owner privileges. This vulnerability highlights the importance of adhering to security best practices in blockchain development and aligns with ATT&CK technique T1059.006 for smart contract manipulation, emphasizing the need for robust input validation and secure coding practices in decentralized applications.