Solana Allowance Security Audit Framework

Delegation Hijacking: The Most Common Breach If your subscription service stores delegate private keys in environment variables, Heroku logs, or unencrypted databases, an attacker with server access owns every active delegation. This is the most common breach vector in production Solana subscription systems. Mitigation: Use a Hardware Security Module (HSM) or Solana-compatible key management service (e.g., AWS CloudHSM, Fireblocks) for all delegate accounts. Your test must confirm that no plaintext key ever touches application memory. --- The Vulnerable Renewal Pattern 1. Owner signs a renewal instruction 2. Delegate transfers tokens to payment recipient 3. Delegate updates subscription state (next_renewal_date, amount_spent) 4. If the payment recipient is a malicious program, it callbacks mid-execution before step 3 completes 5. Attacker sees the allowance was already spent but the renewal period wasn't updated 6. Attacker calls renewal again with the same signature, spending tokens twice This happens because Solana's runtime doesn't prevent reentrancy by default. You must code it.