CVE-2018-13525 in Flow
Summary
by MITRE
The mintToken function of a smart contract implementation for Flow, 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-2018-13525 represents a critical integer overflow flaw within the mintToken function of a smart contract implementation for the Flow token on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types, creating a scenario where malicious actors can manipulate contract state through crafted inputs. The issue specifically affects the token contract's ability to manage user balances correctly, as the overflow condition allows for unexpected behavior in the underlying mathematical operations that govern token creation and distribution.
The technical execution of this vulnerability occurs when the mintToken function processes token minting operations without proper overflow checks, enabling attackers to exploit the contract's arithmetic handling. When an integer overflow occurs, the mathematical operation wraps around to a smaller value, potentially allowing an attacker to manipulate the balance of any user account within the contract. This flaw directly violates the fundamental principles of secure smart contract development and represents a classic example of CWE-191 Integer Underflow/Overflow, where the lack of proper bounds checking in arithmetic operations leads to unpredictable state modifications. The vulnerability operates at the core of the contract's tokenomics, where legitimate minting operations become exploitable by malicious actors seeking to manipulate token distributions.
The operational impact of this vulnerability extends beyond simple balance manipulation, as it fundamentally compromises the integrity of the token economy and user trust in the system. An attacker with malicious intent could potentially inflate their own token holdings or manipulate other users' balances to create artificial scarcity or manipulate market dynamics. This type of vulnerability aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter, where the attacker leverages the contract's own functions against itself to achieve unauthorized state modifications. The consequences include potential financial losses for users, disruption of token functionality, and erosion of confidence in the underlying blockchain platform. The vulnerability also creates opportunities for cascading effects where manipulated balances could impact other contract functions or external systems that depend on accurate token state information.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protections within the smart contract code, including the use of SafeMath libraries or similar arithmetic protection mechanisms that prevent overflow conditions. The contract owner should implement comprehensive input validation and boundary checks before executing any balance modification operations. Additionally, regular security audits and formal verification of smart contract code should be conducted to identify similar vulnerabilities before they can be exploited. The remediation process must include thorough testing of edge cases and overflow scenarios to ensure that all arithmetic operations within the contract maintain proper bounds and do not exhibit unexpected behavior under malicious input conditions.