Intermediate

Smart Contract Security

Intermediate Track 04
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Code is Law β€” Bugs Mean Losses

2023 DeFi hack losses: $180M
Smart contracts cannot be changed after deployment. A single line of bug puts all assets at risk.

What you'll learn in this module

  • β†’ Key smart contract vulnerabilities: reentrancy, integer overflow, access control flaws
  • β†’ Practical defenses: CEI pattern, ReentrancyGuard, and how to apply them in code
  • β†’ The role and importance of formal security audits and bug bounty programs
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Reentrancy

The DAO hack. ~3.6M ETH ($60M) drained. Caused Ethereum's hard fork.

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Overflow

Exceeding uint limit wraps to 0. Solidity 0.8+ prevents this by default.

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Access Control

Admin functions callable by anyone. Parity wallet $30M incident.