The unfavourable effect brought by MEVs continues to gain recognition globally, with many believing MEVs capable of providing serious risk to Ethereum’s future. Amidst this crisis, research organization Flashbots has emerged with a solution.
BlockApex 
December 6, 2021 | Name: Dafi bridge (Final Audit) |
| Auditors: Moazzam Arif | Muhammad Jarir |
| Platform: Ethereum/Solidity |
| Type of review: ETH - BSC Bridge |
| Methods: Architecture Review, Functional Testing, Computer-Aided Verification, Manual Review |
| Git repository: https://github.com/DAFIProtocol/dBridge/tree/dafi-bridge-contracts |
| White paper/ Documentation: Dafi Bridge Flow Document (1).pdf |
| Document log: Initial Audit: 30th November 2021 Final Audit: 2nd December 2021 |
The git-repository shared was checked for common code violations along with vulnerability-specific probing to detect major issues/vulnerabilities. Some specific checks are as follows:
| Code review | Functional review | |
| Reentrancy | Unchecked external call | Business Logics Review |
| Ownership Takeover | ERC20 API violation | Functionality Checks |
| Timestamp Dependence | Unchecked math | Access Control & Authorization |
| Gas Limit and Loops | Unsafe type inference | Escrow manipulation |
| DoS with (Unexpected) Throw | Implicit visibility level | Token Supply manipulation |
| DoS with Block Gas Limit | Deployment Consistency | Asset’s integrity |
| Transaction-Ordering Dependence | Repository Consistency | User Balances manipulation |
| Style guide violation | Data Consistency | Kill-Switch Mechanism |
| Costly Loop | Operation Trails & Event Generation |
A detailed overview of the project can be found here:
https://blog.dafiprotocol.io/introducing-the-dbridge-testnet-c564f5b4eea2
Dafi’s “dbridge” enables users to bring their ERC-20 $DAFI tokens across from the Ethereum network to Binance Smart Chain, and vice versa, with aims of making $DAFI available on multiple high-speed and low-cost networks. As Dafi’s goal is to support every token on most chains, to launch their own dToken, it’s important that their protocol is cross-chain.
Dafi Bridge is an implementation of a generic POA Bridge. Authority is distributed among validators. Validators sign the proof-of-burn message and the user submits (to avoid gas griefing attacks) the signature on the alternate chain to claim tokens.
The codebase:
The system consists of 3 smart contracts (i.e ETH Bridge, BSC Bridge & a burnable/mintable ERC20 token representing Dafi on alternate chains)
Bridge contracts have onlyOwner modifier to set configurations (i.e adding/removing validators, minimum signers required(threshold)).
The analysis indicates that the contracts audited are working properly.
Our team performed a technique called “Filtered Audit”, where the contract was separately audited by two individuals. After their thorough and rigorous process of manual testing, no potential flags were raised.
| # of issues | Severity of the risk |
| 0 | Critical Risk issue(s) |
| 0 | High Risk issue(s) |
| 1 | Medium Risk issue(s) |
| 1 | Low Risk issue(s) |
| 3 | Informatory issue(s) |
No critical-risk issues were found in the review.
No high-risk issues were found in the review.
1. If ETHToken is changed, tokens will be locked forever in the contract
File: ETHBridgeOptimized.sol
Description:
Owner(multisig) can change the underlying ETHToken address. If there are tokens locked in the smart contract and changeToken() is called, tokens will be locked forever in the contract.
Remedy:
Remove changeToken() method from the contract. If there is a need to change the token address, a new contract can be deployed.
Status:
Fixed.
1. Unnecessary allowance check in burn/lock tokens
File: ETHBridgeOptimized.sol, BinanceBridgeOptimized.sol
Description:
if (IERC20(BSCTOKEN).allowance(msg.sender, address(this)) < amount)
revert AllowanceInsufficient(
IERC20(BSCTOKEN).allowance(msg.sender, address(this)), amount);
When burning/locking tokens, the contract checks if the msg.sender has allowed the smart contract (address(this)) to burn/lock. This check will cost extra gas. Normally these checks are used with burnFrom. There is already check placed in the burn method of dafiToken.sol
Remedy:
Remove allowance checks
Status:
Fixed.
1. Misleading variable/function names
File: ETHBridgeOptimized.sol, BinanceBridgeOptimized.sol, dafiTokenBSC.sol
function burnTokens(uint256 amount, address targetChain) external {
function lockTokens(uint256 amount, address targetChain) external {
function viewOwners(address checkAddress) external view returns (bool) //viewValidators
function burn(uint256 _value, address _beneficiary) external onlyBridge { // burnFrom
Remedy:
Our suggestion is that
1. targetChain should be recipient
2. viewOwners should be ViewValidators
2. burn should be burnFrom in dafiToken
2. Gas cost optimization while incrementing nonce
File: ETHBridgeOptimized.sol, BinanceBridgeOptimized.sol
Description:
nonceIncrement() method is used to increment a state variable nonce. Calling a function instead of directly updating the state variable will save the gas cost. Calling a function introduce JUMP opcode which has a higher gas cost
Status:
Fixed.
3. Centralization risk on minting/burning on BSC Token
Description:
onlyBridge can burn/mint tokens. Bridge address can be changed by the owner (MultiSig). There are no potential risks as long as the signers of the multisig are honest.
The smart contracts provided by the client for audit purposes have been thoroughly analyzed in compliance with the global best practices till date w.r.t cybersecurity vulnerabilities and issues in smart contract code, the details of which are enclosed in this report.
This report is not an endorsement or indictment of the project or team, and they do not in any way guarantee the security of the particular object in context. This report is not considered, and should not be interpreted as an influence, on the potential economics of the token, its sale or any other aspect of the project.
Crypto assets/tokens are results of the emerging blockchain technology in the domain of decentralized finance and they carry with them high levels of technical risk and uncertainty. No report provides any warranty or representation to any third-Party in any respect, including regarding the bug-free nature of code, the business model or proprietors of any such business model, and the legal compliance of any such business. No third-party should rely on the reports in any way, including for the purpose of making any decisions to buy or sell any token, product, service or other asset. Specifically, for the avoidance of doubt, this report does not constitute investment advice, is not intended to be relied upon as investment advice, is not an endorsement of this project or team, and it is not a guarantee as to the absolute security of the project.
Smart contracts are deployed and executed on a blockchain. The platform, its programming language, and other software related to the smart contract can have its vulnerabilities that can lead to hacks. The scope of our review is limited to a review of the Solidity code and only the Solidity code we note as being within the scope of our review within this report. The Solidity language itself remains under development and is subject to unknown risks and flaws. The review does not extend to the compiler layer, or any other areas beyond Solidity that could present security risks.
This audit cannot be considered as a sufficient assessment regarding the utility and safety of the code, bug-free status or any other statements of the contract. While we have done our best in conducting the analysis and producing this report, it is important to note that you should not rely on this report only - we recommend proceeding with several independent audits and a public bug bounty program to ensure security of smart contracts.
The unfavourable effect brought by MEVs continues to gain recognition globally, with many believing MEVs capable of providing serious risk to Ethereum’s future. Amidst this crisis, research organization Flashbots has emerged with a solution.
BlockApex 
November 16, 2021 The Deus DAO hack had significant financial consequences, with users collectively losing around $6.5 million across Arbitrum, BSC, and Ethereum chains. Furthermore, the hack caused the DEI stablecoin to depeg by more than 80%, destabilizing its value and potentially shaking investor confidence.
BlockApex
May 24, 2023 The dual nature of Tornado Cash brings forth layers of doubt surrounding its morality. Who benefits more from using Tornado Cash? The average man concerned about his privacy, or a criminal with millions of dollars worth of stolen funds?
BlockApex
November 5, 2021 An off-chain transaction deals with values outside the blockchain and can be completed using a lot of methods. To carry out any kind of transaction, both functioning entities should first be in agreement, after that a third-party comes into the picture to validate it.
BlockApex
February 23, 2022 In a world where personal data has become more or less a commodity, the potential advantages provided by zero-knowledge proofs are monumental. By combining them with blockchain technology, a powerful mix of immutability and security can be achieved.
BlockApex
November 23, 2021 Web 3.0 is a semantic web where it promises to establish information in a better-existing way than any current search engine can ever attain. Web 3.0 promotes four concepts which mainly are authenticity, i.e, every piece of information existing on the internet is a fact or derived from a fact. Integrity, willingness to abide by moral principles, and ethical values. Transparency, the data present on the internet is accessible for every user to witness. Lastly, Confidentiality which is achieved by Blockchain technology, where every user’s identity is anonymous, making it secure.
BlockApex
October 28, 2022 the source code review of Lightlink Bridge Validator and Keeper. The purpose of the assessment was to perform the whitebox testing of the Bridge’s validator and Keeper before going into production and identify potential threats and vulnerabilities.
BlockApex
October 6, 2023 Play-to-earn or P2E for short, typically refers to a business model where players can earn real-world or in-game currency by playing games, completing tasks, and performing different activities. This in-game currency is usually the project’s native cryptocurrency and is used to reward users.
BlockApex
June 28, 2023 The analysis indicates that the contracts audited are secured and follow the best practices.
Our team performed a technique called “Filtered Audit”, where the contract was separately audited by two individuals. After their thorough and rigorous process of manual testing, an automated review was carried out using Slither, and Manticore. All the flags raised were manually reviewed and re-tested.
BlockApex
September 8, 2021 
