Guide to DeFi Security

Introduction

When most people think about DeFi security, their minds go straight to smart contracts. And while blockchain-based vulnerabilities grab headlines, there’s another equally critical surface that too often gets overlooked: the Web2 stack.

In reality, your frontend, APIs, cloud configurations, and backend infrastructure are all prime targets for attackers, and they don’t require deep knowledge of Solidity to exploit. As a company specializing in penetration testing for Web3, we’ve seen firsthand how many DeFi protocols leave themselves exposed at the Web2 layer.

Here’s what you need to know and how to secure your stack.

1. Frontend Vulnerabilities: The First Point of Contact

Your dApp’s frontend is where users connect wallets, interact with protocols, and authorize transactions. A compromised frontend can inject malicious code, redirect funds, or phish credentials.

Common Risks:

• Injection attacks (XSS, DOM-based XSS)
• Supply chain risks via third-party scripts
• Subdomain takeovers
• DNS hijacking

How to Secure It:

• Enforce strict Content Security Policies (CSP)
• Implement Subresource Integrity (SRI) for third-party scripts
• Use 2FA and role-based access to DNS and deployment environments
• Regularly audit dependencies and monitor for changes
• Employ static and dynamic code analysis tools

2. API Security: The Hidden Attack Surface

APIs act as the bridge between your frontend and backend services. Exposed or poorly secured APIs can leak sensitive data, allow unauthorized access, or be abused for logic-based attacks.

Common Risks:

• Broken authentication
• Rate-limiting bypass
• Sensitive data exposure
• Improper permission handling

How to Secure It:

• Require authentication and signature validation for critical endpoints
• Use proper rate-limiting and throttling mechanisms
• Validate and sanitize all user inputs
• Apply least privilege principles to API keys and internal services
• Monitor and log all API activity for anomalies

3. Cloud and DevOps Misconfigurations

Many DeFi teams rely on cloud providers and CI/CD pipelines to deploy and manage infrastructure. These tools offer speed and scale, but they also open the door to severe misconfigurations if not handled with care.

Common Risks:

• Publicly exposed S3 buckets or storage
• Overprivileged IAM roles
• Leaked credentials in repos or build logs
• Unprotected admin interfaces

How to Secure It:

• Conduct regular cloud security reviews and audits
• Rotate credentials and API keys regularly
• Use automated tools to scan for secrets in code
• Enable multi-factor authentication across all cloud services
• Monitor infrastructure for unusual login or deployment behavior

4. User Interface & Wallet Spoofing

A common social engineering vector involves tricking users through fake or altered interfaces. Attackers may clone your frontend, alter wallet connect modals, or inject phishing prompts.

Common Risks:

• Fake wallet popups
• Spoofed domains mimicking your dApp
• Typosquatting with similar domain names

How to Secure It:

• Register similar domains to prevent typosquatting
• Use certificate pinning and HTTPS enforcement
• Educate users to always verify URLs and signatures
• Consider browser extensions or plugins to verify dApp integrity

5. Session & Authentication Risks

Even if your app is decentralized, some components like dashboards or admin panels may require session management. Improper session handling opens the door to hijacking and privilege escalation.

Common Risks:

• Session fixation or reuse
• JWT manipulation
• Lack of logout/invalidation

How to Secure It:

• Use secure, short-lived tokens and refresh mechanisms
• Encrypt tokens at rest and in transit
• Set secure, HttpOnly, SameSite cookie flags
• Invalidate sessions on logout or user state change

Final Thoughts

As the DeFi ecosystem matures, attackers are increasingly shifting their focus to the more “traditional” web stack. That’s why penetration testing and security reviews of your Web2 infrastructure are not optional—they’re essential.