CVE-2018-13466 in Crystals
Summary
by MITRE
The mintToken function of a smart contract implementation for Crystals, 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 • 02/26/2020
The vulnerability identified in CVE-2018-13466 represents a critical integer overflow flaw within the mintToken function of Crystals Ethereum token smart contract implementation. This vulnerability resides in the fundamental arithmetic operations of the smart contract code where insufficient input validation and overflow checking mechanisms allow malicious actors to manipulate token balances. The flaw specifically affects the contract's ability to properly handle large numerical values during token creation and distribution processes, creating a pathway for unauthorized balance manipulation.
The technical exploitation of this vulnerability stems from the absence of proper overflow protection mechanisms within the mintToken function implementation. When the contract attempts to increment token balances or perform arithmetic operations on token quantities, the lack of overflow checks allows values to wrap around to unexpected states. This behavior aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses vulnerabilities where integer arithmetic operations produce results that exceed the maximum value representable by the data type. The vulnerability enables an attacker with ownership privileges to manipulate the balance of any user account within the token contract to arbitrary values, effectively allowing for unlimited token generation or manipulation of existing balances.
The operational impact of this vulnerability extends beyond simple balance manipulation to encompass potential financial loss, contract integrity compromise, and systemic risk within the token ecosystem. An attacker with access to the owner account can create tokens without limit, manipulate existing user balances to zero, or inflate balances to extreme values that could disrupt the token's economic model. This vulnerability directly impacts the core principles of blockchain token economics and trustless systems, as it undermines the fundamental assumption that token balances are immutable and accurately maintained. The exploitability of this flaw is particularly concerning because it requires only owner privileges to execute, making it accessible to contract administrators who may be compromised or malicious actors who gain access to privileged accounts.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protection mechanisms within smart contract code. The recommended approach includes implementing explicit overflow checks using require statements or SafeMath libraries that prevent arithmetic operations from producing results exceeding data type limits. Organizations should also implement comprehensive code review processes specifically focused on arithmetic operations and input validation to prevent similar issues in future deployments. Additionally, regular security audits and formal verification of smart contract code can help identify and remediate such vulnerabilities before they can be exploited. The remediation efforts should align with industry best practices outlined in the Ethereum Smart Contract Security Best Practices and should incorporate defensive programming techniques that prevent integer overflow conditions as specified in the ATT&CK framework's software exploitation techniques.