Don’t Deploy, Verify: A Beginner’s Guide to Smart Contract Audits (EVM & Solana)

In the decentralized world, code is law. A smart contract, once deployed, cannot be easily changed, and a single vulnerability can lead to millions in lost funds (a “hack”).

Whether you are a DeFi user wanting to understand security reports or a new developer building your first token, understanding the audit process is non-negotiable.

This guide breaks down the essential four-step process for auditing smart contracts on the two dominant ecosystems: EVM-compatible chains (like Ethereum, which uses Solidity) and Solana (which uses Rust).

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What is a Smart Contract Audit?

Simply put, a smart contract audit is a methodical, in-depth inspection of the contract’s code by security experts.

Its goal is not just to check for basic bugs, but to uncover deep security flaws, logic errors, and vulnerabilities that an attacker could exploit to steal assets, halt the contract, or manipulate its intended function.

The Four Phases of Every Audit

Professional audits—whether for a simple EVM token or a complex Solana DeFi protocol—follow a consistent lifecycle:

Phase 1: Pre-Audit & Documentation

This is the planning stage. The audit team gathers all documentation from the project developers.

• Code Freeze: The developers must stop making changes to the code. The audit is performed on a fixed snapshot of the code.
• Requirements: Auditors study the whitepaper and technical specifications to understand what the contract is supposed to do. (Example: “Users must be able to stake token X and only receive token Y as a reward.”)
• Test Cases: Auditors run the unit tests written by the developers to ensure the basic functions work as intended.

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Phase 2: Automated Testing (The Robot Check)

Before any human eyes scan the code, the contract is fed into specialized security tools. These automated scanners perform the essential “sanity check,” quickly catching the easiest and most common flaws.

Why Pros Use Automated Tools:

Even the best human auditor can miss a simple overflow error in 10,000 lines of code. Automated tools are essential because they:

1. Enforce Best Practices: They check code against libraries of known vulnerabilities and coding standards.
2. Ensure Consistency: They guarantee that the same rigorous checks are applied to every function, every time.
3. Save Time: They handle the basic checks, allowing human auditors to focus their time on complex business logic and unique attack vectors.

Essential Automated Audit Tools

Ecosystem	Language	Tool Name	Key Function / What it Checks
EVM	Solidity / Vyper	Slither	A powerful static analyzer that reports vulnerabilities (like reentrancy), suggests optimizations, and generates a visual inheritance graph of the contract.
EVM	Solidity	Mythril	Uses symbolic execution to explore every possible execution path of the contract, identifying potential attack vectors and exceptions.
EVM	Solidity	Echidna	A fuzzer that generates random, meaningful inputs to test contract properties (invariants) and break them under unexpected conditions.
Solana	Rust / Anchor	Cargo-Audit	Checks the project’s dependencies against a database of Rust security advisories, ensuring no existing vulnerability is imported.
Solana	Rust / Anchor	Clippy	The standard Rust linter. It checks for common code mistakes, style issues, and often spots functional errors or inefficient coding patterns.
Both	-	Formal Verification (e.g., CertiK’s engine)	A highly advanced technique that mathematically proves a contract’s logic is correct and adheres to its specifications, eliminating entire classes of errors.

Beginner Tip: Automated tools are fast, but they often produce false positives (flagging secure code as risky) or miss complex logical errors that only a human can spot. This is why the next phase is crucial.

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Phase 3: Manual Review (The Deep Dive)

This is where the human expertise comes in. A security researcher manually reads every line of code to find the flaws the automated tools missed.

• Logic Review: Checking if the code makes sense against the project’s requirements. Does a function allow the owner to accidentally lock up all the funds?
• Attack Vectors: Auditors think like hackers, attempting to exploit common vulnerabilities:
  • Reentrancy: Can a function be recursively called to drain funds (a famous Ethereum attack)?
  • Access Control: Are critical functions (like updating parameters) protected so only the owner or governance can call them?
  • Front-Running: Can users see a pending transaction and execute a trade ahead of it for profit?
• Architecture Review: Checking how different contracts or programs interact, especially on Solana where Cross-Program Invocation (CPI) introduces unique security risks.

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Phase 4: Reporting, Remediation, and Final Report

The findings are compiled and published for the developers and the public.

1. Initial Report: Auditors classify every issue found by severity (Critical, Major, Medium, Minor, Informational).
2. Remediation: The developers work to fix the issues based on the report’s recommendations.
3. Re-Audit (Optional but Recommended): The auditors check the fixed code to ensure the patches didn’t introduce new problems.
4. Final Report: The public document is released, showing the original findings and noting whether each vulnerability was Resolved or remains Unresolved.

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Key Vulnerabilities to Look For (The Common Red Flags)

When reading an audit report or reviewing a contract, keep an eye out for these classic vulnerabilities:

EVM (Solidity) Specifics

• Integer Overflow/Underflow: This happens when a number gets too large or too small for its data type. Since Solidity v0.8.0, this is checked automatically, but it is a major issue in older or unchecked code.
• Function Visibility: Functions meant to be called internally are accidentally marked public, allowing anyone to execute them.
• Gas Optimization: While not a security flaw, inefficient code can cost users much higher transaction fees (Gas).

Solana (Rust) Specifics

Solana’s design introduces an account model that requires careful checks.

• Account Validation/Cranking: On Solana, the calling program must pass all necessary accounts to a function. If the program fails to validate that the accounts are correct, signed, or belong to the right program, an attacker can substitute a fake account.
• Signer Checks: The program must ensure that the expected user wallet has actually signed the transaction before performing a critical action (like withdrawing funds).
• Anchor Constraints: If using the Anchor framework, auditors check for correct usage of #[account] constraints, which are essential for security.

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The Takeaway for DeFi Users

As a user, you are the final check. When a project launches:

1. Look for a Public Audit Report: If a project doesn’t have one, it’s a huge red flag.
2. Check the Firm’s Reputation: Is the audit from a known, respected firm, or an unknown entity?
3. Read the Severity: Don’t panic over “Informational” or “Minor” findings, but Critial and Major bugs must be marked as Resolved before you consider investing.

The audit is a stamp of approval—not a bulletproof vest—but it shows the team has taken security seriously.

Reputable Smart Contract Auditing Firms

When checking a project’s documentation, look for reports from firms known for their rigor and expertise across multiple chains. Note that many firms specialize; some are best for EVM, others for Solana or cutting-edge cryptographic systems.

Firm Name	Primary Specialization	Key Focus
CertiK	Multi-chain (EVM, Solana, etc.)	Formal Verification (mathematical proof) and AI-powered real-time monitoring (Skynet).
Trail of Bits	High-Assurance, Infrastructure	Known for deep security research, high-stakes audits, and advanced cryptographic systems.
OpenZeppelin	EVM (Ethereum ecosystem)	Provides standardized, secure Solidity libraries and is a core developer-focused security partner.
Quantstamp	Multi-chain (EVM, Solana, etc.)	Focuses on consistency, depth, and pioneering work in formal verification.
Hacken	Multi-chain (EVM, Solana, etc.)	Comprehensive security suite including smart contract audits, bug bounties, and compliance.
PeckShield	EVM, Monitoring	Strong expertise in smart contract audits and real-time on-chain vulnerability monitoring/incident response.
Halborn	Solana & EVM	Actively collaborates within the Solana ecosystem and provides full-stack security services.
ConsenSys Diligence	EVM (Ethereum ecosystem)	Backed by the ConsenSys team (MetaMask), specializing in high-profile Ethereum projects (Aave, 0x).

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