Static Analysis for Smart Contracts: Slither and Mythril
A missed reentrancy or incorrect storage layout can cost millions. Blockchain history has seen cases where millions of ETH were lost due to reentrancy. Automated code review of smart contracts using Slither and Mythril helps detect such issues before deployment.
We analyze your code with Slither and Mythril — it's like an X-ray for your smart contract. Every line is checked for common vulnerabilities and inefficient patterns. Combining these tools gives a good balance of speed and depth. Slither processes an average contract in seconds, while Mythril explores complex execution paths in minutes. Our engineers tune the detectors to your stack and filter out false positives (typically 10-20% for Slither, <5% for Mythril). As a result, you get a report with precise recommendations. In one project, correcting the storage layout saved 15% gas on every call, equivalent to $30,000 per month. According to Mythril's documentation, symbolic execution can find vulnerabilities that static analysis alone misses.
What Static Analysis of Smart Contracts Detects?
Static analysis automatically finds common vulnerabilities without running the code:
- Reentrancy — the classic vector (TheDAO incident). Slither detects unsafe external calls.
- Incorrect storage layout — wrong struct packing or field order leads to extra SLOADs and excessive gas.
- Access control issues — missing modifiers, incorrect owner checks.
- Arithmetic overflows (Solidity <0.8) — before built-in checks.
- Using
tx.origin— phishing attacks. - Unchecked external call return values — ignoring send/transfer success.
Slither uses over 100 detectors covering 90% of the top-25 CWE vulnerabilities. Mythril can detect time-dependent and ordering issues that static analysis cannot see.
How We Perform the Analysis
The process includes two stages:
- Automated Slither run with a set of 100+ detectors. We get a list of potential bugs with line numbers.
- Symbolic execution with Mythril — checking complex paths that Slither might miss (e.g., conditional branches).
A typical medium-complexity contract (500–1000 lines of Solidity) is processed in 1–2 hours. The result is a detailed report with severity breakdown and fix examples. We also manually review every critical section to eliminate false negatives. Our team has audited over 50 projects, including multichain protocols.
Tool Comparison — Automated Security Analysis for Smart Contracts
| Tool | Type | Speed | Depth | False Positives |
|---|---|---|---|---|
| Slither | Static analysis | Seconds–minutes | High (detector-based) | Medium (10–20%) |
| Mythril | Symbolic execution | Minutes–hours | Very high (path-based) | Low (<5%) |
Foundry forge inspect |
AST analysis | Seconds | Medium (custom checks) | Low |
Slither is roughly 10x faster than Mythril for surface-level analysis, but Mythril finds vulnerabilities Slither misses. That's why we use both.
Example of a false positive
Slither may report a reentrancy vulnerability in a function that uses OpenZeppelin's `ReentrancyGuard`. The detector doesn't always account for modifiers — this requires manual verification.Typical Errors We Find
| Error | Description | Impact |
|---|---|---|
_msgSender() used without context (ERC-2771) |
Authentication logic broken | Loss of funds |
Missing _beforeTokenTransfer check in ERC-1155 |
Incorrect transfer possible | Balance attack |
Improper eth handling in receive() |
Reentrancy on send | Complete loss of control |
Using block.timestamp for randomness |
Miner attacks | Predictability |
One of our clients prevented a $1.2 million loss due to a reentrancy bug discovered during the audit. In another cross-chain bridge project, we identified a vulnerability that could have led to a $500k loss. On average, we find 5-10 critical vulnerabilities per contract.
How the Audit Works: Step by Step
- Preparation: You provide contracts, tests, and documentation.
- Automated run: Slither scans the code and outputs warnings.
- Symbolic execution: Mythril checks complex paths and deep vulnerabilities.
- Manual review: Our engineers analyze every critical section.
- Report: Detailed description, POC, recommendations, and fixed code.
- Retest: After your fixes, we run another scan (typically takes 1-2 days).
What's Included in Our Work
We don't just run scanners — we offer a complete cycle:
- Audit using Slither, Mythril, and Foundry.
- Manual review — especially for sensitive operations (withdrawals, mint/burn).
- Report: description of each vulnerability, proof (POC or exploit code), recommendation.
- Retest after your fixes.
- Gas optimization guide (if applicable).
Additionally: security hardening consultation, CI pipeline integration with Slither.
Why Static Analysis Before Deployment?
Fixing a vulnerability after deployment costs tens of times more than before. Early audits prevent critical bugs and reduce the risk of fund loss. According to our statistics, static analysis finds an average of 5–10 critical vulnerabilities per contract.
Our Advantages
Our team has years of experience developing and auditing DeFi, NFT, and infrastructure contracts. We have reviewed over 50 projects, including multichain protocols. We guarantee confidentiality and NDA.
Order an audit today — secure your project. Get a personalized consultation on your contracts — contact us.