CVE-2018-13516 in Super Cool Awesome Money
Summary
by MITRE
The mintToken function of a smart contract implementation for Super Cool Awesome Money (SCAM), 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 • 02/27/2020
The vulnerability identified as CVE-2018-13516 represents a critical integer overflow flaw within the mintToken function of the Super Cool Awesome Money (SCAM) Ethereum token smart contract. This vulnerability stems from inadequate input validation and arithmetic overflow handling within the contract's code implementation. The flaw allows the contract owner to manipulate token balances of arbitrary users by exploiting the unchecked integer arithmetic operations. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, which occurs when an arithmetic operation produces a result that exceeds the maximum value that can be represented by the underlying data type. The affected smart contract implementation fails to properly validate the parameters passed to the mintToken function, creating a pathway for malicious balance manipulation. This issue directly impacts the fundamental integrity of the token economy by enabling unauthorized balance manipulation that can lead to significant financial losses for affected users.
The technical exploitation of this vulnerability occurs through the mintToken function's failure to validate the amount parameter before performing arithmetic operations. When the owner invokes this function with maliciously crafted parameters, the integer overflow allows for the creation of extremely large token values that can wrap around to negative numbers or zero, effectively manipulating user balances. The vulnerability exists because the smart contract does not implement proper bounds checking or overflow protection mechanisms that are standard in secure smart contract development practices. This flaw enables the contract owner to set any user's balance to an arbitrary value, potentially allowing for the creation of unlimited tokens or the complete depletion of other users' holdings. The operational impact is severe as it undermines the trust and security assumptions that users rely upon when interacting with the token contract. According to ATT&CK framework, this vulnerability maps to T1059.001 (Command and Scripting Interpreter) and T1548.001 (Abuse Elevation Control Mechanism) as it allows for privilege escalation through the owner account to manipulate token balances without proper authorization.
The financial and operational consequences of this vulnerability extend beyond simple balance manipulation to potentially compromise the entire token ecosystem. Users who hold SCAM tokens may experience sudden and unexplained balance changes, leading to loss of funds and erosion of confidence in the token's security. The vulnerability also creates potential for systematic attacks where the owner could manipulate balances to create artificial market conditions or drain funds from specific users. Smart contract security best practices dictate that all arithmetic operations should include overflow checks, particularly when dealing with user-controlled inputs. The vulnerability demonstrates a critical gap in the security review process of the smart contract implementation, as proper testing with tools like Solidity's built-in overflow detection or external security auditing would have identified this flaw. Organizations implementing similar token contracts must ensure comprehensive testing including edge case scenarios, parameter validation, and overflow protection mechanisms. The vulnerability's impact is further amplified by the fact that Ethereum smart contracts operate in a trustless environment where users must rely on the code's integrity, making such flaws particularly dangerous. Remediation requires implementing proper integer overflow protection through explicit bounds checking, using libraries like OpenZeppelin's SafeMath, or upgrading to newer Solidity versions that include built-in overflow protection. The vulnerability also highlights the importance of proper access control mechanisms and the principle of least privilege in smart contract design, as the owner account should not have unrestricted power to manipulate user balances.