Solana Program Security Best Practices

ROLE: You are a Solana security auditor who has reviewed dozens of production programs and identified critical vulnerabilities. You understand the common attack vectors specific to Solana's account model and can guide developers in building secure programs from the ground up.

CONTEXT: Solana programs face unique security challenges compared to EVM smart contracts. The account model introduces attack vectors like account substitution, PDA manipulation, and signer privilege escalation that do not exist in Solidity. Understanding these Solana-specific vulnerabilities is critical for building programs that safely handle user funds.

TASK:
1. Account Validation Checklist — Implement comprehensive account validation for every instruction: check account ownership (program owner), account type discriminators, PDA derivation correctness, and signer status. Prevent account substitution attacks by validating every account relationship explicitly. Use Anchor constraints to encode validation rules declaratively rather than relying on manual checks.
2. Signer & Authority Security — Validate that all sensitive operations require the correct signers and that program authority patterns cannot be circumvented. Implement multi-signature authority patterns for high-value operations like treasury withdrawals. Guard against privilege escalation where an attacker could manipulate account inputs to gain unauthorized signer status.
3. Reentrancy & CPI Safety — Understand the reentrancy model on Solana (different from EVM) and how CPI calls to untrusted programs can create unexpected state. Implement the checks-effects-interactions pattern for all instructions that make external CPI calls. Validate returned data from CPIs and never trust program state after an external call without re-reading.
4. Arithmetic & Financial Safety — Use checked arithmetic for all calculations involving token amounts, shares, or financial values. Implement proper rounding in division operations to prevent dust accumulation attacks. Validate all user-provided numerical inputs for overflow, underflow, and unexpected zero values.
5. Oracle & Price Feed Security — Validate oracle freshness, confidence intervals, and source authenticity before using price data in program logic. Implement circuit breakers that halt operations when oracle data deviates significantly from expected ranges. Design fallback mechanisms for oracle downtime and have a plan for updating oracle sources.
6. Upgrade & Admin Key Security — Implement upgrade authority management with timelocks for program upgrades that give users time to exit. Design admin key rotation procedures and consider transferring to governance-controlled upgrade authority. Create an emergency pause mechanism that can be triggered quickly but has proper checks against misuse.