CVE-2018-13494 in SusanTokenERC20
Summary
by MITRE
The mintToken function of a smart contract implementation for SusanTokenERC20, 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 in CVE-2018-13494 represents a critical integer overflow flaw within the mintToken function of the SusanTokenERC20 smart contract implementation on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic handling within the contract's code, creating a scenario where the contract owner can manipulate user balances arbitrarily. The flaw specifically manifests when the mintToken function processes token minting operations without adequate overflow checks, allowing for malicious manipulation of token supply and user account balances.
The technical implementation of this vulnerability aligns with CWE-190, which categorizes integer overflow conditions that can lead to unexpected behavior in software systems. In the context of Ethereum smart contracts, this vulnerability exploits the fundamental arithmetic operations within the contract's code where unsigned integer operations can exceed their maximum representable values. When the mintToken function executes with maliciously crafted parameters, the integer overflow results in the balance calculation wrapping around to an unintended value, effectively allowing the contract owner to set any user's balance to a predetermined amount. This behavior violates the expected tokenomics and security assumptions of ERC-20 compliant tokens.
The operational impact of this vulnerability extends beyond simple balance manipulation and creates significant risks for token holders and the broader ecosystem. An attacker with access to the contract owner account can essentially create unlimited tokens for themselves while simultaneously setting other users' balances to zero or other arbitrary values. This capability undermines the fundamental principles of token distribution and can lead to complete loss of funds for affected users. The vulnerability also compromises the integrity of the token's supply mechanism, potentially enabling market manipulation and undermining trust in the token's value. Additionally, this flaw can be exploited to create a denial of service condition by setting user balances to zero, effectively freezing their tokens.
Mitigation strategies for CVE-2018-13494 must address both immediate remediation and long-term security improvements. The primary fix involves implementing proper overflow and underflow checks within the mintToken function using modern Solidity practices such as the SafeMath library or compiler versions that include built-in overflow protection. Contract owners should also implement proper access controls and audit procedures to prevent unauthorized access to privileged functions. The vulnerability highlights the importance of comprehensive smart contract auditing and adherence to security best practices. Organizations should consider implementing multi-signature wallets for privileged functions and regular security assessments to identify similar vulnerabilities. This case exemplifies the ATT&CK technique T1548.001 for privilege escalation, where an attacker exploits a flaw to gain elevated privileges within the contract system. The vulnerability also demonstrates the need for proper input validation as outlined in the OWASP Top 10 security principles, particularly focusing on preventing arithmetic overflow conditions that can be exploited for financial gain and system compromise.