API Security in Web3

In this lightning talk, Daniel Anomfueme (Technical Project Manager & Web3 tinkerer) unpacks the critical importance of API security in decentralized applications. While blockchains themselves may be secure, the APIs that connect wallets, dApps, and bridges often become the weakest, and most exposed, attack surface.

Daniel walks through real-world Web3 hacks including the Ronin Bridge exploit ($625M), Harmony Bridge ($100M+), and Bybit Safe API compromise, showing how attackers exploited unsecured endpoints, exposed keys, and weak access controls.

The talk identifies common Web3 API threats such as leaked keys, replay attacks, insecure CORS, rate-limit bypasses, and trusted misuse. Daniel then shares practical defenses, from wallet-based authentication (SIWE) to scoped/rotated API keys, JWT/OAuth2 enforcement, rate limiting, and active monitoring for leaks.

For builders, security researchers, and anyone working in Web3 infrastructure, this session is a concise but powerful guide to protecting APIs, the true firewall of decentralized systems.

Transcript

1. API Security in Web3 Protecting Decentralized Applications from Common Threats
2. Daniel Anomfueme Technical Project Manager, Tinkerer. Twitter: @lifeofdanel
3. Why API Security in Web3 Matters? • Web3 runs on APIs: RPCs, REST, GraphQL, WalletAuth. • Security breaches = massive financial loss + trust erosion. • APIs are often the weakest but most public surface.
4. Real Hacks From The Wild Ronin Bridge - $625m exploit Private API Keys + Validator API access Compromised Harmony Bridge - $100m+ Exploited unsecured cross-chain RPC/API. Bybit Safe Hack Attackers exploited weak API key protections and whitelisted withdrawals.
5. Common Web3 API Threats Threat Example Exposed API keys Leaked in frontend apps or public GitHub repos Replay attacks Repeating signed wallet transactions Rate-limit bypass Sybil attacks via multiple identities Insecure CORS Permissive origins in frontend exposes backend No Auth Open endpoints without JWT/SIWE/wallet checks Trusted misuse Whitelisted APIs used to exfiltrate funds (Bybit)
6. Practical Defenses • Use wallet-based auth (e.g. SIWE) • Scope and rotate API keys • Implement rate limiting and request logging • Use JWTs or OAuth2 for internal APIs • Monitor leaks: frontend code, GitHub, Postman collections • Validate whitelist logic and transaction intents
7. Why APIs Matter Even More in Web3 • APIs expose trustless systems to the world • Hackers don’t need to break the chain—just your endpoint • Decentralized doesn’t mean secure by default
8. Final Thoughts • APIs are your firewall in Web3 • Secure early. Monitor often. Educate always. • Remember, security is an illusion
9. Thank you