CVE-2018-13503 in South Park Token Token
Summary
by MITRE
The mintToken function of a smart contract implementation for South Park Token Token (SPTKN), 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-2018-13503 affects the South Park Token Token (SPTKN) smart contract deployed on the Ethereum blockchain, representing a critical integer overflow flaw within the mintToken function. This vulnerability stems from inadequate input validation and arithmetic operation handling within the contract's codebase, specifically when processing token minting operations. The flaw allows the contract owner to manipulate user balances arbitrarily, creating a fundamental breach in the token's integrity and security model. The vulnerability manifests due to the absence of proper bounds checking in the mintToken function, enabling the owner to bypass normal token issuance constraints and directly manipulate account balances through crafted input parameters.
The technical implementation of this vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which occurs when a program performs arithmetic operations on integer values that exceed the maximum representable value for the data type. In the context of Ethereum smart contracts, this typically happens when unsigned integer variables exceed their maximum value and wrap around to zero or negative values, creating unexpected behavior. The SPTKN contract's mintToken function fails to validate the parameters passed to it, particularly the amount parameter that determines how many tokens to mint for a specific user. When an attacker or authorized owner passes maliciously crafted values, the arithmetic operations within the function can overflow, allowing the contract to assign arbitrary balance values to any user account.
The operational impact of this vulnerability extends beyond simple balance manipulation, creating a comprehensive threat vector that compromises the entire token ecosystem. The contract owner can potentially inflate user balances to extremely high values, leading to potential theft of funds or manipulation of token economics. This vulnerability undermines the fundamental principles of blockchain tokenomics, as it allows for unauthorized minting of tokens beyond the intended supply limits. The implications are particularly severe because the token owner can target specific users to drain liquidity from the system or create artificial scarcity by manipulating balances of competing tokens. This type of vulnerability directly impacts the trust model of decentralized applications and can lead to significant financial losses for users who hold the affected tokens.
Mitigation strategies for CVE-2018-13503 require immediate implementation of comprehensive code auditing and security hardening measures. The primary solution involves adding proper input validation and overflow checks to the mintToken function, ensuring that all arithmetic operations are bounded and validated before execution. The contract should implement require statements to validate that the amount parameter does not exceed reasonable limits and that the resulting balance calculations remain within valid integer ranges. Additionally, the contract owner should consider implementing access controls that limit the mintToken function's capabilities to prevent unauthorized balance manipulation. This vulnerability also highlights the importance of following secure coding practices as outlined in the OWASP Smart Contract Security Verification Standard, which recommends comprehensive testing of all arithmetic operations and proper validation of external inputs. Organizations should conduct thorough security assessments and consider using formal verification methods to identify similar vulnerabilities in their smart contract implementations. The ATT&CK framework for blockchain security would categorize this vulnerability under the privilege escalation category, as it allows an authorized user to gain unauthorized control over other users' balances, representing a significant compromise of the contract's security model and user trust.