---
id: wiki-2026-0508-smart-contract-auditing
title: Smart Contract Auditing
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Solidity Audit, Web3 Security Audit, Contract Security Review]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [security, web3, solidity, audit, ai-security]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: solidity
  framework: foundry/slither/mythril
---

# Smart Contract Auditing

## 매 한 줄
> **"매 smart contract audit 의 layered defense — static (Slither) + symbolic (Mythril/Manticore) + fuzz (Echidna/Foundry invariant) + formal (Certora) + AI (Claude / GPT-5 audit) + human review"**. 매 2026 의 reality 의 single tool 의 X — 매 ensemble + AI-augmented review 의 ROI 의 best. 매 SWC registry, 매 Trail of Bits 의 building security in 의 reference.

## 매 핵심

### 매 Tool layers
- **Static (Slither, Aderyn)**: 매 known pattern detector — reentrancy, tx.origin, ...
- **Symbolic (Mythril, Manticore)**: 매 path explore + SMT solver.
- **Fuzz (Echidna, Foundry invariant)**: 매 property-based.
- **Formal (Certora Prover, halmos)**: 매 spec proof.
- **AI (Claude Opus 4.7, GPT-5, OpenZeppelin AI)**: 매 nuanced logic bug, NatSpec 의 intent vs code 의 mismatch.

### 매 Common vuln (SWC)
- **Reentrancy** (SWC-107): CEI pattern, ReentrancyGuard.
- **Integer over/underflow**: Solidity 0.8+ checked, 매 unchecked block 의 careful.
- **Access control**: onlyOwner, role-based, 매 init function 의 protect.
- **Oracle manipulation**: 매 single-block TWAP X, Chainlink + heartbeat.
- **MEV / front-run**: commit-reveal, private mempool.

### 매 응용
1. **Pre-deploy audit** — 매 mainnet deploy 의 prerequisite.
2. **CI gate** — 매 PR 의 Slither / Foundry test 의 fail 의 block.
3. **Bug bounty** — Immunefi 등록 의 ongoing.
4. **Upgrade audit** — UUPS / Transparent proxy 의 upgrade diff review.

## 💻 패턴

### Slither CI (GitHub Actions)
```yaml
name: slither
on: [push, pull_request]
jobs:
  analyze:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: crytic/slither-action@v0.4.0
        with:
          fail-on: medium
          slither-args: "--exclude-informational --filter-paths node_modules"
```

### Foundry invariant test
```solidity
// test/Invariant.t.sol
import "forge-std/Test.sol";
import {Vault} from "src/Vault.sol";

contract VaultInvariant is Test {
    Vault vault;
    address[] users;

    function setUp() public {
        vault = new Vault();
        for (uint i; i < 5; i++) users.push(makeAddr(string(abi.encodePacked("u", i))));
    }

    function invariant_totalShares_eq_sumBalances() public view {
        uint sum;
        for (uint i; i < users.length; i++) sum += vault.balanceOf(users[i]);
        assertEq(vault.totalSupply(), sum);
    }
}
```

### Reentrancy (CEI + Guard)
```solidity
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";

contract Pool is ReentrancyGuard {
    mapping(address => uint) public balance;

    // BAD
    function withdrawBad() external {
        uint b = balance[msg.sender];
        (bool ok,) = msg.sender.call{value: b}("");  // 매 external before state
        require(ok);
        balance[msg.sender] = 0;
    }

    // GOOD: CEI + nonReentrant
    function withdraw() external nonReentrant {
        uint b = balance[msg.sender];
        balance[msg.sender] = 0;                      // Effects
        (bool ok,) = msg.sender.call{value: b}("");   // Interaction
        require(ok, "send fail");
    }
}
```

### Echidna property test
```solidity
contract VaultEchidna is Vault {
    function echidna_no_negative_balance() public view returns (bool) {
        // 매 reachable balance 의 always >= 0 (uint, but check via burn)
        return totalSupply() >= 0;
    }

    function echidna_total_eq_deposits() public view returns (bool) {
        return address(this).balance == totalDeposited;
    }
}
// echidna . --contract VaultEchidna --test-mode property
```

### AI audit (Claude 4.7)
```python
import anthropic
client = anthropic.Anthropic()

def ai_audit(contract_src: str) -> str:
    msg = client.messages.create(
        model="claude-opus-4-7",
        max_tokens=4000,
        system="""You are a senior smart contract auditor. Review for:
1. Reentrancy, access control, integer issues
2. Oracle / price manipulation
3. Logic bugs vs NatSpec intent
4. Gas / DoS
5. Upgrade safety
For each finding: severity (H/M/L), location, exploit, fix.""",
        messages=[{"role": "user", "content": f"```solidity\n{contract_src}\n```"}],
    )
    return msg.content[0].text
```

### Certora spec
```
// MyToken.spec
methods {
    function balanceOf(address) external returns (uint) envfree;
    function totalSupply() external returns (uint) envfree;
}

invariant totalSupply_eq_sum_balances()
    totalSupply() == sumOfBalances()
    { preserved transfer(address to, uint amt) with (env e) {
        require balanceOf(e.msg.sender) >= amt;
    } }
```

### Chainlink oracle (safe)
```solidity
import "@chainlink/contracts/src/v0.8/shared/interfaces/AggregatorV3Interface.sol";

contract PriceConsumer {
    AggregatorV3Interface immutable feed;
    uint constant STALE = 3600;

    function price() public view returns (uint) {
        (, int answer,, uint updatedAt,) = feed.latestRoundData();
        require(answer > 0, "neg price");
        require(block.timestamp - updatedAt < STALE, "stale");
        return uint(answer);
    }
}
```

## 매 결정 기준
| 상황 | Tool |
|---|---|
| CI gate | Slither + Foundry test |
| Pre-deploy | Slither + Mythril + Echidna + AI + human |
| High-value protocol | + Certora formal |
| Upgrade | diff + storage layout check |
| Bounty | Immunefi |

**기본값**: Slither CI + Foundry invariant + AI review + manual senior review before mainnet.

## 🔗 Graph

## 🤖 LLM 활용
**언제**: NatSpec vs code intent diff, logic bug, gas optimization, exploit hypothesis 의 generate.
**언제 X**: deterministic detection (Slither faster), formal proof (Certora).

## ❌ 안티패턴
- **Single tool reliance**: 매 Slither alone 의 logic bug miss.
- **No mainnet rehearsal**: 매 fork test X.
- **Owner = EOA**: 매 multisig / timelock 의 use.
- **Unchecked external call**: low-level call 의 return 의 ignore.

## 🧪 검증 / 중복
- Verified (Trail of Bits, OpenZeppelin, ConsenSys Diligence).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — full content with tool stack + AI audit pattern |