Security

Overview

POIDH v3 implements multiple layers of security to address vulnerabilities discovered in v2. This document outlines the security architecture, threat models, and mitigation strategies.

Critical Security Improvements

1. Reentrancy Protection

All state-changing external functions are protected by OpenZeppelin's ReentrancyGuard:

function example() external nonReentrant {
    // Checks
    // Effects
    // Interactions
}

Mitigates: Reentrancy attacks during external calls

2. Pull Payment System

No direct ETH transfers to users:

// Instead of push payments:
// payable(recipient).transfer(amount); // ❌ VULNERABLE

// We use pull payments:
pendingWithdrawals[recipient] += amount; // ✅ SECURE

Users must explicitly call withdraw() to claim funds.

Mitigates: Reentrancy during ETH transfers, gas griefing

3. Strict CEI Pattern

All functions follow Checks-Effects-Interactions ordering:

function acceptSoloClaim(uint256 bountyId, uint256 claimId) 
    external 
    nonReentrant 
{
    // 1. CHECKS
    Bounty storage bounty = bounties[bountyId];
    require(bounty.issuer == msg.sender, "Not issuer");
    require(bounty.claimer == address(0), "Already claimed");
    
    // 2. EFFECTS
    bounty.claimer = claims[claimId].issuer;
    bounty.amount = 0;
    claims[claimId].accepted = true;
    pendingWithdrawals[claims[claimId].issuer] += bounty.amount;
    
    // 3. INTERACTIONS
    poidhNft.transferFrom(address(this), bounty.issuer, claimId);
}

Mitigates: State manipulation during callbacks

4. Callback-Free NFT Transfers

Claim NFTs use transferFrom instead of safeTransferFrom:

// Mint directly to contract (no callback)
poidhNft.mint(address(this), tokenId);

// Transfer without callback
poidhNft.transferFrom(address(this), recipient, tokenId);

Mitigates: Malicious contract callbacks during NFT transfers

Threat Model

External Threats

graph TB
    subgraph "Attack Vectors"
        A[Reentrancy]
        B[Callback Attacks]
        C[Front-running]
        D[Griefing]
        E[MEV]
    end
    
    subgraph "Mitigations"
        A --> A1[ReentrancyGuard]
        B --> B1[No safeTransferFrom]
        C --> C1[Commit-reveal schemes]
        D --> D1[Pull payments]
        E --> E1[Deadline protection]
    end
    
    style A fill:#dc2626
    style B fill:#dc2626
    style A1 fill:#059669
    style B1 fill:#059669

Known Vulnerabilities Addressed

V2 Exploit: ERC721 Callback Reentrancy

Description: Attacker created malicious contract that reentered during safeTransferFrom in claim acceptance.

V3 Fix:

• Removed safeTransferFrom
• Use transferFrom (no callback)
• Mint NFTs directly to contract
• All functions nonReentrant

V2 Exploit: Incomplete State Finalization

Description: State updates after external calls allowed manipulation.

V3 Fix:

• Strict CEI pattern
• All state changes before external calls
• bounty.amount = 0 before any transfers

Security Properties

Invariants

The following invariants are maintained and tested:

1. Bounty Total Invariant: Sum of contributions = bounty amount
2. Withdrawal Invariant: Total pending withdrawals = contract ETH balance
3. Participant Invariant: participants.length - freeParticipantSlots.length = active participants
4. Claim Uniqueness: Each claim can only be accepted once
5. Voting Weight: Total votes = sum of participant contributions

Access Control

graph LR
    subgraph "Functions"
        A[createSoloBounty]
        B[acceptSoloClaim]
        C[createOpenBounty]
        D[joinOpenBounty]
        E[vote]
        F[withdraw]
    end
    
    subgraph "Access Control"
        A --> A1[Anyone]
        B --> B1[Bounty Issuer Only]
        C --> C1[Anyone]
        D --> D1[Anyone]
        E --> E1[Participants Only]
        F --> F1[Funds Recipient Only]
    end
    
    style B1 fill:#2563eb
    style E1 fill:#2563eb

Testing Coverage

Unit Tests

• ✅ All function paths
• ✅ Access control
• ✅ Input validation
• ✅ State transitions

Fuzz Tests

• ✅ Randomized inputs
• ✅ Property-based testing
• ✅ Invariant checking

Invariant Tests

• ✅ Withdrawal invariant
• ✅ Participant invariant
• ✅ Bounty total invariant

Red Team Tests

• ✅ V2 exploit reproduction
• ✅ Reentrancy attempts
• ✅ Callback attacks
• ✅ Front-running scenarios

Remaining Risks

Economic Griefing

Risk: Participants can vote maliciously to reject valid claims.

Mitigation:

• Weighted voting (larger contributors have more influence)
• No financial penalty for rejected claims
• Claimants can resubmit

Liveness Risk

Risk: Open bounties with no voting activity stall permanently.

Mitigation:

• resetVotingPeriod allows extending voting window
• Bounty issuer can cancel after voting expires

MEV Exposure

Risk: Front-running of last-minute votes, claim submissions.

Mitigation:

• Fixed voting period (2 days)
• Vote weight = contribution (hard to game last-minute)
• No immediate execution on vote completion

Admin Key Risk

Risk: Treasury address and voting period are immutable after deployment.

Mitigation:

• Immutable = no rug risk
• Multi-sig treasury recommended
• Clear documentation of parameters

Security Checklist

Pre-Deployment

• [x] All tests passing
• [x] 95%+ code coverage
• [x] Fuzz tests run with 10,000+ runs
• [x] Invariant tests run with 2,000+ runs
• [x] Manual code review completed
• [x] Security report reviewed

Post-Deployment

• [ ] Monitor for unusual activity
• [ ] Watch for gas spikes
• [ ] Track bounty/claim volumes
• [ ] Monitor voting patterns
• [ ] Audit trail for all transactions

Incident Response

If vulnerability discovered:

1. Pause protocol (if pause mechanism added)
2. Alert community
3. Deploy fix
4. Migrate to new contract
5. Post-mortem

Audit Status

Status: Not audited by professional firm

Recommendation: Obtain professional audit before mainnet deployment with significant value.

Self-Review: Comprehensive security review conducted, documented in docs/POIDH_V3_SECURITY_REPORT.md

Additional Resources

• Security Report: Available in project docs
• Mainnet Readiness: Available in project docs
• Test Results: Available in project docs
• Vulnerability Reporting: See SECURITY.md in project root