audit-slippage

name	audit-slippage
description	Audits Solidity DEX integrations and smart contracts for slippage vulnerabilities enabling sandwich attacks including zero/missing minAmountOut parameters, block.timestamp or missing deadlines, on-chain slippage calculation via manipulable quoters, multi-hop swaps without final output protection, decimal precision mismatches between token pairs, hard-coded slippage preventing withdrawals during volatility, and fixed fee tier assumptions breaking when liquidity migrates
allowed-tools	Read, Grep, Glob
license	MIT
compatibility	Designed for Claude Code (or similar products)
metadata	{"author":"Tomasz Kowalczyk ([e-mail])","version":"1.0"}

Slippage Protection Auditor

When to Use

• Auditing DEX integrations, AMM interactions, swap operations
• User mentions: slippage, MEV, sandwich attack, front-running, deadline, minAmountOut, swap, Uniswap, Curve, Balancer
• Reviewing token exchange functions, liquidity operations, router integrations
• Analyzing price impact protection in DeFi protocols

Audit Workflow

IMPORTANT: Announce skill usage at the start of analysis

Begin with: "I'm using the audit-slippage skill to analyze this contract for slippage protection and MEV vulnerabilities..."

1. Identify swap/liquidity operations

   • Search: swap, addLiquidity, removeLiquidity, IUniswapV2Router, ISwapRouter
   • Focus: minAmountOut parameters, deadline parameters, quoter usage

2. Check against vulnerability patterns

   • Reference reference.md for complete checklist
   • Compare code against example.md

3. Validate MEV exploitability

   • Check access control first - grep for onlyOwner|onlyAdmin|onlyGovernance modifiers
   • Can non-privileged actors exploit via MEV?
   • Can MEV bot sandwich attack?
   • Calculate extractable value (% of trade)
   • Check if protection exists elsewhere in call stack
   • Downgrade severity if admin-only unless users affected by MEV

4. Generate report

   • Use deliverable template below
   • Include sandwich attack PoC
   • Quantify MEV extraction potential

Core Vulnerability Patterns

See reference.md for full checklist. Key patterns:

1. No slippage parameter (minAmountOut = 0) → 99%+ value extractable
2. No expiration deadline (type(uint256).max) → delayed execution risk
3. block.timestamp as deadline → zero protection
4. Incorrect slippage calculation → wrong reference value
5. Mismatched slippage precision → decimal scaling errors
6. Hard-coded slippage → withdrawal failures during volatility
7. MinTokensOut for intermediate amount → multi-hop unprotected
8. On-chain slippage calculation → flash loan manipulation
9. Fixed fee tier assumption → routing through wrong pool
10. Slippage on token amount not USD value → market crash risk
11. No slippage on liquidity ops → LP value extraction
12. Flash swap repayment without slippage → overpayment risk
13. Approval race on router upgrade → MEV via old router

Code examples: See example.md

Severity Criteria

Critical: Zero slippage on user-facing swaps, missing deadline, on-chain quoter-based minOut, MUST be exploitable by non-privileged actors High: Hard-coded slippage preventing withdrawals, intermediate-hop-only protection, wrong fee tier (80%+ liquidity elsewhere), MUST be exploitable by non-privileged actors Medium: Wrong decimal precision (user can retry), suboptimal routing, missing LP operation slippage, admin-only swap functions with cascading user MEV exposure Low: Suboptimal slippage (token vs USD) in stable pairs, documentation issues, admin-only swap parameter issues without immediate user impact

IMPORTANT: Admin-only swap functions (onlyOwner, onlyAdmin, onlyGovernance) are MEDIUM or LOW severity unless:

• Admin swaps use user funds directly (e.g., fee collection selling user-deposited tokens)
• Missing slippage enables admin to extract value from protocol treasury holding user funds
• Admin swap parameters affect user swap routing or slippage calculations

False Positives - Do NOT Flag

• Zero slippage on internal protocol-to-protocol swaps (both sides controlled)
• block.timestamp deadline in keeper/bot functions with off-chain slippage enforcement
• Hard-coded slippage in emergency-only functions with explicit warnings
• On-chain quoter in view functions (display/estimation only)
• Fixed fee tier with documented single-pool targeting
• Admin-only swap functions (onlyOwner, onlyAdmin) swapping protocol-owned assets not derived from user funds
• Governance-controlled swaps with timelock allowing users to exit before execution
• Treasury management swaps where admin has no access to user deposits

Deliverable Format

MANDATORY: Before deliverable, verify each checklist.md item against codebase. Flag violations as findings.

Use template: templates/report-template.md

Each finding includes: severity, pattern #, file/lines, description, vulnerable code, impact (MEV extraction %), PoC with sandwich attack simulation, remediation, gas impact.

Key Principles

• User control - users specify slippage and deadline per tx
• Off-chain calculation - minAmountOut from off-chain or TWAP, never current block
• Final output protection - multi-hop must protect final amount, not intermediate
• Decimal awareness - account for token decimal differences

Output Guidelines

DO:

• Reference specific lines/functions
• Provide sandwich attack PoCs
• Quantify MEV extraction ($ or %)
• Include real-world exploit examples

DON'T:

• Flag view/pure functions (no state change)
• Report intentional designs without exploit path
• Use vague terms
• Ignore liquidity depth context