Front-Running Vulnerability Scanner

WHAT IT DOES

Front-Running Vulnerability Scanner is a read-only security tool that analyzes EVM smart contracts for potential front-running, sandwich attack, and MEV exploitation vectors. It examines contract bytecode to identify public write functions that could be exploited by mempool watchers, detects vulnerability patterns like re-entrancy and unprotected state changes, and simulates mempool activity to assess the likelihood of front-running. The tool provides a risk score from "low" to "critical" along with specific recommendations for mitigation, helping developers and auditors identify attack surfaces before deployment.

HOW TO USE

Connect your EVM-compatible wallet via the BGWallet bridge and select the network where your target contract is deployed. Paste the contract address and click "Scan for Front-Running Vulnerabilities". The tool fetches the bytecode, extracts function signatures, analyzes each function for front-running risk factors, and checks for known vulnerability patterns. Results include a risk level, lists of high/medium-risk functions, detected vulnerability patterns, mempool activity indicators, and actionable recommendations. All analysis is read-only—no signatures or transactions are submitted.

TECHNICAL MECHANISM

The tool uses ethers.js v5.7.2 to fetch contract bytecode via provider.getCode(address), then performs static analysis to extract function signatures using opcode pattern matching (0x63 for PUSH4 selectors). Each detected function is evaluated against a database of front-running risk patterns including swap, transfer, approve, deposit, withdraw, stake, claim, mint, burn, addLiquidity, removeLiquidity, and generic execution functions. Risk scoring weights functions by their potential for value extraction (swap = 3, deposit/withdraw = 3, approval = 2, etc.) and combines with vulnerability pattern detection (re-entrancy indicators, SELFDESTRUCT, REVERT usage) and mempool activity simulation based on function count and risk profile. The tool also checks for known vulnerable opcode sequences like 0x73 (CALL) followed by 0x74 (state-changing operations) that indicate potential re-entrancy. Results are aggregated into a composite risk score that determines the overall risk level and generates targeted mitigation recommendations.

WHAT IT CANNOT SEE

This tool has fundamental limitations that users must understand. It cannot predict future mempool ordering or guarantee that a detected vulnerability will be exploited—a function may be high-risk in theory but protected by access controls or timelocks. It cannot see private mempools such as Flashbots, MEV-Boost, or any transaction submitted directly to miners via private channels, which means real front-running activity may occur that the tool cannot observe. It cannot detect cross-chain front-running or off-chain ordering manipulation that happens outside the EVM mempool. It cannot analyze proxy contracts fully—if the target address is a proxy, the tool only sees the proxy's minimal bytecode and cannot scan the implementation contract unless the user provides that address directly. It cannot perform dynamic analysis or simulate actual transaction execution, so it may miss complex vulnerability paths that require specific state conditions. The tool's function signature extraction is heuristic and may miss functions that are obfuscated, dynamically generated, or use non-standard dispatch patterns. It also cannot detect front-running risks in contracts that rely on off-chain price feeds or oracles that update at different frequencies.

PLEASE NOTE

This tool only supports EVM-compatible blockchains (Ethereum, Polygon, BSC, Avalanche C-Chain, Optimism, Arbitrum, and their testnets). Solana, Tron, Starknet, SUI, TON, Aptos, Bitcoin, Cosmos, and XRP are not supported. The tool is free, open-source, requires no API keys, and uses the wallet's native provider for all read operations.