CVE-2018-13077 in CTB
Summary
by MITRE
The mintToken function of a smart contract implementation for CTB, 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 • 02/24/2020
The vulnerability identified in CVE-2018-13077 represents a critical integer overflow flaw within the mintToken function of a smart contract implementation for CTB tokens 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. The flaw allows an attacker with owner privileges to manipulate token balances by setting arbitrary values for user accounts, effectively bypassing normal token minting and distribution mechanisms. The vulnerability directly maps to CWE-190, which describes integer overflow conditions where an integer value exceeds the maximum representable value for its data type, and CWE-191, which addresses integer underflow conditions. The security implications extend beyond simple balance manipulation as this flaw can be leveraged to create unlimited tokens, potentially leading to complete control over the token economy and undermining the fundamental principles of blockchain-based asset management.
The technical execution of this vulnerability occurs through the mintToken function which likely performs arithmetic operations without proper overflow checks before updating user balances. When the contract attempts to increment token balances or perform calculations involving token amounts, the integer overflow allows malicious actors to manipulate the resulting values to achieve desired outcomes. The vulnerability is particularly dangerous because it requires minimal privileges - only the contract owner account needs to be compromised or the owner can directly exploit the flaw. This makes it a high-impact issue that can result in significant financial loss for token holders and the broader ecosystem. The flaw also aligns with ATT&CK technique T1548.001, which involves privilege escalation through exploitation of software vulnerabilities, and T1078.004, which covers legitimate credentials used for persistence and privilege escalation in cloud environments where smart contracts operate.
The operational impact of this vulnerability extends far beyond immediate financial damage, as it fundamentally compromises the trust model that underpins blockchain-based token systems. An attacker can manipulate user balances to create artificial wealth or drain accounts, effectively creating a scenario where the token supply becomes completely unreliable. The vulnerability also affects the contract's integrity by allowing unauthorized modification of user states, potentially leading to cascading effects throughout the token ecosystem. Token holders lose confidence in the system when such fundamental flaws exist, and the entire economic model of the token can be compromised. The vulnerability's impact is amplified by the fact that smart contracts execute automatically without human intervention, meaning that any exploit can occur instantaneously and without detection. Organizations and developers must implement comprehensive input validation, use safe arithmetic libraries, and conduct thorough security audits to prevent such issues. The vulnerability also highlights the importance of following secure coding practices for blockchain applications, including the use of overflow protection mechanisms, proper access control implementations, and regular security assessments to identify and remediate similar flaws before they can be exploited in production environments.