CVE-2018-19833 in DDQ
Summary
by MITRE
The owned function of a smart contract implementation for DDQ, an tradable Ethereum ERC20 token, allows attackers to change the owner of the contract, because the function does not check the caller's identity.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 01/01/2020
The vulnerability identified as CVE-2018-19833 represents a critical access control flaw within the smart contract implementation of DDQ, a tradable Ethereum ERC20 token. This issue stems from a fundamental design oversight in the contract's ownership management system where the owned function lacks proper authentication mechanisms to verify the identity of callers attempting to modify ownership. The flaw directly violates core security principles of decentralized applications by allowing any external entity to assume control over the contract without proper authorization.
The technical root cause of this vulnerability aligns with CWE-284, which addresses improper access control in software systems. In the context of blockchain smart contracts, this manifests as a failure to implement adequate authorization checks within the contract's administrative functions. The owned function in question should have enforced that only the current owner could execute ownership transfers, but instead operates as a public function that accepts any caller's input. This design flaw creates an arbitrary write vulnerability where malicious actors can simply call the function with their own address as the new owner parameter, effectively hijacking the contract's control.
From an operational impact perspective, this vulnerability presents severe consequences for the DDQ token ecosystem and its stakeholders. The ability to arbitrarily change contract ownership opens the door to complete contract takeover scenarios where attackers can drain funds, modify tokenomics, or disable critical contract functionality. The vulnerability affects the fundamental trust model of the ERC20 token implementation, as users cannot rely on the contract's ownership remaining stable or controlled by legitimate parties. This type of attack falls under the ATT&CK technique T1548.001 for hijacking legitimate credentials, though in the blockchain context, it represents a more fundamental compromise of the contract's access control mechanism.
The mitigation strategy for this vulnerability requires immediate implementation of proper access control checks within the owned function. The contract should enforce that only the current owner can execute ownership transfers by implementing a require statement that validates the caller's address against the stored owner address. Additionally, the contract should implement a two-step ownership transfer process where the new owner must explicitly accept the transfer, preventing accidental or malicious ownership changes. This aligns with best practices recommended in the Solidity documentation for secure smart contract development and addresses the core issue identified in the vulnerability description. The fix should also consider implementing timelocks for ownership transfers to provide additional security layers and prevent rapid takeover scenarios.