Solana Dev Arc 12: How to Audit Programs for Account Validation Flaws

A structured seven-day coding arc (Days 78–84) focused on auditing Solana programs for security vulnerabilities rooted in faulty account validation rather than complex cryptography. Developers reviewed existing Anchor programs by examining each instruction for missing ownership checks, signature requirements, and PDA verification. The exercise involved writing adversarial transactions, applying property-based testing and fuzzing, and reproducing a real account-substitution exploit. A key takeaway was that Anchor constraints such as Signer, has_one, seeds, and bump should handle most validations before the instruction handler ever runs. The guiding principle throughout was that every account and input must be treated as untrusted until the program explicitly proves otherwise.