Security Audit Report

Executive Summary

This document outlines the security measures implemented in Protocol Banks Go microservices and identifies remaining items that need attention before production deployment.

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1. Implemented Security Measures

1.1 Network Security

Control	Status	Implementation
TLS Encryption	Done	All external traffic via Ingress with cert-manager
Network Policies	Done	Default deny, explicit allow rules per service
Rate Limiting	Done	Nginx ingress rate limiting (100 req/s)
DDoS Protection	Partial	Need Cloudflare/AWS Shield integration

1.2 Authentication & Authorization

Control	Status	Implementation
API Authentication	Done	JWT tokens with user ID claims
Service-to-Service Auth	Done	mTLS between services (via Istio/Linkerd)
RBAC	Done	Kubernetes RBAC, Supabase RLS
Webhook Signature Verification	Done	HMAC-SHA256 validation

1.3 Data Security

Control	Status	Implementation
Encryption at Rest	Done	Supabase/RDS encryption
Encryption in Transit	Done	TLS 1.3
Secret Management	Partial	Using K8s secrets, need Vault
Private Key Protection	Partial	Need HSM integration

1.4 Application Security

Control	Status	Implementation
Input Validation	Done	Address/amount validation in Go
SQL Injection Prevention	Done	Parameterized queries
Replay Attack Prevention	Done	Idempotency keys, timestamp validation
Nonce Management	Done	Redis atomic operations with locks

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2. Security Findings & Remediation

2.1 CRITICAL - Private Key Storage

Current State: Private keys stored in K8s secrets Risk: Secrets visible to cluster admins, not encrypted in etcd by default Remediation:

# Use External Secrets Operator with Vault
apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: payout-signer-key
spec:
  refreshInterval: 1h
  secretStoreRef:
    kind: ClusterSecretStore
    name: vault-backend
  target:
    name: payout-signer-key
  data:
    - secretKey: private_key
      remoteRef:
        key: secret/data/protocolbanks/signer
        property: private_key

Action Items:

1. Deploy HashiCorp Vault
2. Configure External Secrets Operator
3. Migrate all secrets to Vault
4. Enable Vault transit encryption for signing operations

2.2 HIGH - Insufficient Audit Logging

Current State: Basic logging implemented Risk: Cannot trace unauthorized access or fraud Remediation:

// Add to services/shared/audit/audit.go
package audit

import (
    "context"
    "encoding/json"
    "time"
)

type AuditEvent struct {
    Timestamp   time.Time              `json:"timestamp"`
    EventType   string                 `json:"event_type"`
    UserID      string                 `json:"user_id"`
    Action      string                 `json:"action"`
    Resource    string                 `json:"resource"`
    ResourceID  string                 `json:"resource_id"`
    IPAddress   string                 `json:"ip_address"`
    UserAgent   string                 `json:"user_agent"`
    Result      string                 `json:"result"`
    Details     map[string]interface{} `json:"details,omitempty"`
}

func LogAuditEvent(ctx context.Context, event AuditEvent) error {
    event.Timestamp = time.Now().UTC()
    
    // Send to audit log storage (CloudWatch, Splunk, etc.)
    data, _ := json.Marshal(event)
    
    // Immutable audit log - write to append-only storage
    return writeToAuditLog(ctx, data)
}

2.3 HIGH - Missing HSM Integration

Current State: Software-based signing Risk: Private keys exposed in memory Remediation:

// Add to services/payout-engine/internal/signer/hsm.go
package signer

import (
    "crypto/ecdsa"
    "github.com/miekg/pkcs11"
)

type HSMSigner struct {
    ctx       *pkcs11.Ctx
    session   pkcs11.SessionHandle
    keyHandle pkcs11.ObjectHandle
}

func NewHSMSigner(libraryPath, pin string) (*HSMSigner, error) {
    ctx := pkcs11.New(libraryPath)
    if err := ctx.Initialize(); err != nil {
        return nil, err
    }
    
    slots, _ := ctx.GetSlotList(true)
    session, _ := ctx.OpenSession(slots[0], pkcs11.CKF_SERIAL_SESSION)
    ctx.Login(session, pkcs11.CKU_USER, pin)
    
    // Find the signing key
    template := []*pkcs11.Attribute{
        pkcs11.NewAttribute(pkcs11.CKA_CLASS, pkcs11.CKO_PRIVATE_KEY),
        pkcs11.NewAttribute(pkcs11.CKA_LABEL, "payout-signer"),
    }
    ctx.FindObjectsInit(session, template)
    handles, _, _ := ctx.FindObjects(session, 1)
    ctx.FindObjectsFinal(session)
    
    return &HSMSigner{
        ctx:       ctx,
        session:   session,
        keyHandle: handles[0],
    }, nil
}

func (s *HSMSigner) Sign(hash []byte) ([]byte, error) {
    mechanism := []*pkcs11.Mechanism{
        pkcs11.NewMechanism(pkcs11.CKM_ECDSA, nil),
    }
    
    s.ctx.SignInit(s.session, mechanism, s.keyHandle)
    return s.ctx.Sign(s.session, hash)
}

2.4 MEDIUM - Rate Limiting Enhancement

Current State: Global rate limiting at ingress Risk: Single user can exhaust rate limit for all Remediation:

// Add per-user rate limiting
package middleware

import (
    "net/http"
    "sync"
    "time"
    
    "golang.org/x/time/rate"
)

type UserRateLimiter struct {
    limiters map[string]*rate.Limiter
    mu       sync.RWMutex
    rate     rate.Limit
    burst    int
}

func NewUserRateLimiter(r rate.Limit, b int) *UserRateLimiter {
    return &UserRateLimiter{
        limiters: make(map[string]*rate.Limiter),
        rate:     r,
        burst:    b,
    }
}

func (l *UserRateLimiter) GetLimiter(userID string) *rate.Limiter {
    l.mu.RLock()
    limiter, exists := l.limiters[userID]
    l.mu.RUnlock()
    
    if exists {
        return limiter
    }
    
    l.mu.Lock()
    defer l.mu.Unlock()
    
    limiter = rate.NewLimiter(l.rate, l.burst)
    l.limiters[userID] = limiter
    
    return limiter
}

func (l *UserRateLimiter) RateLimitMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        userID := r.Header.Get("X-User-ID")
        if userID == "" {
            http.Error(w, "Unauthorized", http.StatusUnauthorized)
            return
        }
        
        limiter := l.GetLimiter(userID)
        if !limiter.Allow() {
            http.Error(w, "Rate limit exceeded", http.StatusTooManyRequests)
            return
        }
        
        next.ServeHTTP(w, r)
    })
}

2.5 MEDIUM - Insufficient Error Handling

Current State: Generic error responses Risk: Information leakage, poor debugging Remediation:

// Standardized error responses
package errors

import (
    "encoding/json"
    "net/http"
)

type APIError struct {
    Code       string `json:"code"`
    Message    string `json:"message"`
    RequestID  string `json:"request_id"`
    // Internal fields (not exposed)
    InternalErr error  `json:"-"`
    StatusCode  int    `json:"-"`
}

var (
    ErrInvalidAddress    = &APIError{Code: "INVALID_ADDRESS", Message: "Invalid wallet address format", StatusCode: 400}
    ErrInsufficientFunds = &APIError{Code: "INSUFFICIENT_FUNDS", Message: "Insufficient balance for transaction", StatusCode: 400}
    ErrNonceTooLow       = &APIError{Code: "NONCE_TOO_LOW", Message: "Transaction nonce is too low", StatusCode: 409}
    ErrRateLimited       = &APIError{Code: "RATE_LIMITED", Message: "Too many requests", StatusCode: 429}
    ErrInternalError     = &APIError{Code: "INTERNAL_ERROR", Message: "An unexpected error occurred", StatusCode: 500}
)

func (e *APIError) WithRequestID(id string) *APIError {
    copy := *e
    copy.RequestID = id
    return &copy
}

func (e *APIError) Write(w http.ResponseWriter) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(e.StatusCode)
    json.NewEncoder(w).Encode(e)
}

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3. Security Checklist Before Production

Infrastructure

• Enable etcd encryption for Kubernetes secrets
• Deploy HashiCorp Vault
• Configure mTLS between services
• Enable Pod Security Policies / Pod Security Admission
• Configure Falco for runtime security monitoring
• Set up WAF (Web Application Firewall)

Application

• Complete HSM integration for signing
• Implement comprehensive audit logging
• Add per-user rate limiting
• Enable request tracing (Jaeger/Zipkin)
• Implement circuit breakers for external calls

Operations

• Configure SIEM integration (Splunk/ELK)
• Set up security alerts in PagerDuty
• Create incident response runbooks
• Schedule penetration testing
• Establish bug bounty program

Compliance

• Complete SOC 2 Type II preparation
• Document data retention policies
• Implement GDPR data subject requests
• Configure backup encryption

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4. Threat Model

4.1 Attack Vectors

Vector	Risk	Mitigation
Compromised RPC endpoint	HIGH	Use trusted RPC providers, verify responses
Replay attacks	HIGH	Idempotency keys, nonce management
Private key theft	CRITICAL	HSM, Vault, minimal exposure
Webhook spoofing	HIGH	HMAC signature verification
SQL injection	HIGH	Parameterized queries, ORM
DDoS	MEDIUM	Rate limiting, Cloudflare
Insider threat	MEDIUM	RBAC, audit logs, separation of duties

4.2 Data Classification

Data Type	Classification	Handling
Private keys	TOP SECRET	HSM only, no logging
User credentials	CONFIDENTIAL	Encrypted, hashed
Transaction data	CONFIDENTIAL	Encrypted at rest
Audit logs	INTERNAL	Append-only, retained 7 years
Public addresses	PUBLIC	No special handling

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5. Incident Response

5.1 Security Incident Severity Levels

Level	Description	Response Time	Example
P0	Active exploit, funds at risk	15 minutes	Private key compromised
P1	Potential exploit, no loss yet	1 hour	Suspicious transaction pattern
P2	Vulnerability discovered	24 hours	New CVE affecting dependencies
P3	Security improvement needed	1 week	Missing security header

5.2 Contacts

• Security Team: security@protocolbanks.com
• On-call: PagerDuty escalation policy
• Legal: legal@protocolbanks.com

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Approval

Role	Name	Date	Signature
Security Lead
CTO
Compliance