/web3
/web3-auditAudit de sécurité de smart contracts avec la méthodologie des 10 classes de bugs.
name: web3-audit
description: Smart contract security audit — runs through 10 bug class checklist (accounting desync, access control, incomplete path, off-by-one, oracle errors, ERC4626, reentrancy, flash loan, signature replay, proxy/upgrade). Applies pre-dive kill signals first. Generates Foundry PoC template for confirmed findings. Usage: /web3-audit <contract.sol>
/web3-audit
Smart contract security audit using the 10-bug-class methodology.
Usage
/web3-audit VulnerableContract.sol
/web3-audit https://github.com/protocol/contracts
/web3-audit [paste contract code]Step 0: Pre-Dive Kill Signals
ALWAYS check these BEFORE reading any code:
1. TVL < $500K → max payout too low for effort → SKIP
2. 2+ top-tier audits (Halborn, ToB, Cyfrin, OZ) on simple protocol → SKIP
3. Protocol < 500 lines, single A→B→C flow → minimal attack surface → SKIP
4. max_payout = min(10% × TVL, program_cap) → if < $10K → SKIP
Formula: Is [TVL * 10%] > [hours I'll spend * hourly rate]? If not, skip.Only proceed if score >= 6/10:
- TVL > $10M: +2
- Immunefi Critical >= $50K: +2
- No top-tier audit on current version: +2
- < 30 days since deploy: +1
- Protocol you've hunted before: +1
- Upgradeable proxies present: +1
Step 1: Accounting State Desynchronization (28% of Criticals)
# Find accounting variables
grep -rn "totalSupply\|totalShares\|totalAssets\|totalDebt\|cumulativeReward" contracts/
# Find ALL early returns in critical functions
grep -rn "\breturn\b" contracts/ -B3 | grep -B3 "if\b"Check: For each early return in claim/redeem/withdraw functions:
- Which state variables are updated in the normal path?
- Are ALL of them also updated in the early return path?
- If A updated but B isn't → potential desync bug
Step 2: Access Control (19% of Criticals)
# Sibling function families — do ALL have same modifier set?
grep -rn "function vote\|function poke\|function reset\|function update\|function claim\|function harvest" contracts/ -A2
# Ownership check: existence vs ownership
grep -rn "_requireOwned\|ownerOf\|_isApprovedOrOwner" contracts/ -B5
# Silent modifiers (if without revert)
grep -rn "modifier\b" contracts/ -A8 | grep -B3 "if (" | grep -v "require\|revert"
# Uninitialized proxy
grep -rn "function initialize\b" contracts/ -A3
grep -rn "_disableInitializers()" contracts/Check: Does EVERY sibling function in a family have the SAME modifiers?
Step 3: Incomplete Code Path (17% of Criticals)
The function family comparison test:
1. List all state changes in function A (deposit/place/create)
2. List all state changes in function B (withdraw/update/cancel)
3. For each state change in A: does B have the corresponding reverse?
4. For each token transfer in A: does B have the corresponding refund?grep -rn "safeApprove\b" contracts/ # safeApprove without zero-reset?
grep -rn "delete\b" contracts/ -B5 # delete before operation completes?
grep -rn "function deposit\|function mint\|function withdraw\|function redeem" contracts/ -A10Step 4: Off-By-One (22% of Highs)
Mental test: For EVERY if (A > B): "What happens when A == B?" Is that correct?
# Boundary comparisons
grep -rn "Period\|Epoch\|Deadline\|period\|epoch\|deadline" contracts/ -A3 | grep "[<>][^=]"
# Loop breaks
grep -rn "\bbreak\b" contracts/ -B10
# Array bounds
grep -rn "\.length\s*-\s*1\|i\s*<=\s*.*\.length\b" contracts/Step 5: Oracle / Price Manipulation
# Missing staleness check
grep -rn "latestRoundData" contracts/ -A5 | grep -v "updatedAt\|timestamp"
# Pyth confidence interval
grep -rn "getPriceUnsafe\|getPrice\b" contracts/ -A8 | grep -v "conf\|confidence"
# TWAP windows
grep -rn "secondsAgo\|TWAP\|cardinality" contracts/ -A5Check:
- Is staleness checked? (
require(block.timestamp - updatedAt <= MAX_AGE)) - Is Pyth confidence interval checked? (
require(conf * 10 <= price)) - Is TWAP window > 1800 seconds (30 min)?
Step 6: ERC4626 Vaults
grep -rn "function deposit\|function mint\|function withdraw\|function redeem" contracts/ -A10
grep -rn "function transfer\|function transferFrom" contracts/ -A15Check:
- Does
mint()call the same validation asdeposit()? - Does
transfer()move lock records along with shares? - Is there a
_decimalsOffset()virtual shares defense against first-depositor attack?
Step 7: Reentrancy
# Effects after interactions
grep -rn "\.call{value\|safeTransfer\|transfer(" contracts/ -B10 | grep -v "require\|revert"
# Missing nonReentrant
grep -rn "function withdraw\|function redeem\|function claim" contracts/ -A2 | grep -v "nonReentrant"Check: Does every function that transfers ETH or ERC20 follow CEI order?
(Checks → Effects → Interactions)
Step 8: Flash Loan Oracle Manipulation
grep -rn "getReserves\|getAmountsOut\|slot0\b" contracts/ -A5Check: Any spot price reading from Uniswap reserves/slot0? → flash loan manipulatable.
