Breaking to Secure: Blockchain Penetration Testing for a Cross-Chain DeFi Platform

Client Profile

The client is a decentralized finance (DeFi) platform enabling cross-chain asset swaps, yield farming, and liquidity provision across Ethereum, Arbitrum, and Polygon. With over $300M in total value locked (TVL) and frequent protocol upgrades, the client needed assurance against evolving threats – including contract-level exploits, bridge vulnerabilities, and oracle manipulation. Their goal was to proactively uncover and fix exploitable security gaps before malicious actors could exploit them.

Challenges Faced

Key security concerns included:

  • Complex cross-chain architecture increasing attack surface
  • Potential for flash loan and price oracle manipulation
  • Smart contract upgradeability introducing logic flaws
  • Lack of prior formal penetration testing against the protocol stack
Solution

COE Security conducted a comprehensive Blockchain Penetration Testing Engagement, combining:

  • Smart Contract Exploit Simulation: Assessed reentrancy, logic flaws, and access control gaps in Solidity-based contracts
  • Cross-Chain Bridge Testing: Validated integrity, transaction verification, and replay protections on bridge infrastructure
  • Oracle Manipulation Testing: Simulated time-weighted average price (TWAP) attacks and single-source price feeds
  • Infrastructure and API Layer Testing: Probed RPC endpoints, GraphQL APIs, and validator node exposure
Offensive Testing, Defensive Results
  • Exploited flash loan loophole that could drain liquidity pools within 4 seconds
  • Bypassed contract access restrictions via misconfigured proxy upgrade path
  • Identified insecure fallback functions exposing core logic to misuse
  • Flagged insecure randomness source in reward distribution logic
  • Found unprotected emergency functions callable by non-admin accounts
Strategic Insights & Governance Alignment
  • Delivered risk-scored attack surface map across smart contracts, bridges, and APIs
  • Developed mitigation strategies for high-risk functions with compensating controls
  • Advised on secure deployment practices and smart contract lifecycle governance
  • Created a custom checklist for secure upgrades and testnet-to-mainnet migrations
Offensive Security for Blockchain
  • Full-stack Blockchain Penetration Testing
  • Smart Contract Exploit Simulation
  • Flash Loan & Oracle Abuse Testing
  • Bridge & Cross-Chain Protocol Attacks
  • API & RPC Endpoint Security Assessment
  • Secure Upgrade & Proxy Testing
  • Wallet, Signature & Transaction Tampering
  • Blockchain Fuzzing & Static Analysis
  • DeFi Protocol Adversarial Simulation
  • Post-Test Code Review & Patch Validation
Implementation Details
  • Audited and tested over 30 smart contracts and 3 bridge protocols
  • Conducted black-box and white-box testing in staging and production environments
  • Used proprietary fuzzers and exploit kits tailored for DeFi
  • Delivered a final PenTest report with detailed Proof of Concept (PoC) exploits
  • Conducted a joint patch review session with the client’s developers and DevOps team
Results Achieved
  • Identified 21 vulnerabilities (6 critical, 8 high, 7 medium) with zero false positives
  • Enabled secure deployment of Version 2 contracts and bridge modules
  • Achieved a 90% reduction in attack surface based on remediation coverage
  • Helped secure a successful $50M funding round with external audit verification
Client Testimonial

“COE Security didn’t just find bugs – they understood our architecture, challenged our assumptions, and made our protocol truly resilient. Their blockchain penetration testing is top-tier.”