Security Best Practices

Write secure smart contracts and manage vulnerabilities effectively.

Overview

This section provides guidance on:

• Writing secure smart contract code
• Preparing for security audits
• Establishing continuous security processes
• Addressing common vulnerability patterns

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Quick Links

Guide	Description
Pre-Audit Checklist	Prepare contracts for audit
Continuous Security	Ongoing security practices
Common Vulnerability Patterns	Frequent issues and fixes
Remediation Priorities	Prioritizing fixes
Solidity Security Tips	Solidity-specific guidance
Vyper Security Tips	Vyper-specific guidance
DeFi Security Considerations	DeFi-specific issues

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Security Fundamentals

Defense in Depth

Layer multiple security measures:

1. Design - Secure architecture
2. Code - Secure implementation
3. Testing - Comprehensive test coverage
4. Review - Peer and external review
5. Monitoring - Runtime monitoring

Principle of Least Privilege

Minimize access and capabilities:

• Functions should have minimal permissions
• Use role-based access control
• Separate admin functions
• Time-lock sensitive operations

Fail Safely

When errors occur, fail securely:

• Use require statements
• Validate all inputs
• Handle edge cases explicitly
• Prefer reverting over returning false

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Security Development Lifecycle

1. Design Phase

• Threat modeling
• Security requirements
• Architecture review
• Known pattern selection

2. Development Phase

• Use vetted libraries (OpenZeppelin)
• Follow coding standards
• Write security tests
• Self-review code

3. Testing Phase

• Unit tests for all functions
• Integration tests
• Fuzz testing
• Invariant testing

4. Review Phase

• Internal code review
• BlockSecOps scanning
• External audit (if needed)
• Bug bounty program

5. Deployment Phase

• Staged rollout
• Monitoring setup
• Incident response plan
• Upgrade path ready

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BlockSecOps Integration

During Development

Run quick scans on every PR:

# CI configuration
on: pull_request
preset: quick
fail_on: critical

Before Merge

Run standard scans before merging:

on: push to main
preset: standard
fail_on: high

Pre-Audit

Run deep scans before external audit:

preset: deep
scanners: all

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Common Mistakes

1. Not Using Standard Libraries

// BAD: Custom implementation
function transfer(address to, uint256 amount) public {
    balances[msg.sender] -= amount; // Unsafe
    balances[to] += amount;
}

// GOOD: Use OpenZeppelin
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract Token is ERC20 { ... }

2. Missing Access Control

// BAD: Anyone can call
function setOwner(address newOwner) public {
    owner = newOwner;
}

// GOOD: Restricted access
function setOwner(address newOwner) public onlyOwner {
    owner = newOwner;
}

3. Ignoring Return Values

// BAD: Ignoring return value
token.transfer(to, amount);

// GOOD: Check return value
bool success = token.transfer(to, amount);
require(success, "Transfer failed");

// BEST: Use SafeERC20
SafeERC20.safeTransfer(token, to, amount);

4. Reentrancy Vulnerabilities

// BAD: External call before state update
function withdraw() public {
    uint256 amount = balances[msg.sender];
    (bool success, ) = msg.sender.call{value: amount}("");
    balances[msg.sender] = 0;  // Too late!
}

// GOOD: Checks-Effects-Interactions
function withdraw() public nonReentrant {
    uint256 amount = balances[msg.sender];
    balances[msg.sender] = 0;  // Update first
    (bool success, ) = msg.sender.call{value: amount}("");
    require(success);
}

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Recommended Tools

Development

Tool	Purpose
OpenZeppelin	Secure contract library
Foundry	Testing and development
Hardhat	Development environment

Testing

Tool	Purpose
Foundry Fuzz	Fuzz testing
Echidna	Property testing
Halmos	Symbolic testing

Scanning

Tool	Purpose
BlockSecOps	Comprehensive scanning
Slither	Static analysis
Mythril	Symbolic execution

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Security Resources

Standards

• SWC Registry - Smart Contract Weakness Classification
• EIP Standards - Ethereum standards
• OpenZeppelin Docs - Security patterns

Learning

• Damn Vulnerable DeFi
• Ethernaut CTF
• Capture the Ether

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Getting Help

BlockSecOps Support

• Check Troubleshooting
• Contact support for Enterprise plans
• Community Discord for questions

When to Get an Audit

Consider external audit for:

• TVL > $1M expected
• Novel mechanisms
• Complex DeFi integrations
• Before mainnet launch

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Next Steps

Start with these guides:

1. Pre-Audit Checklist - Prepare your code
2. Common Vulnerability Patterns - Know the risks
3. Continuous Security - Build secure processes