# Security Audit Report

- **Auditor Role**: Security Auditor
- **Date**: 2026-08-06
- **Repository HEAD**: `715873b2ecc3a72ba974bb2a2be87c5ba82bd4e7`
- **Included Scope**: `backend/src/auth/**/*`, `backend/src/common/**/*`, `.env.example`, `docker-compose.yml`, `nginx.conf`, frontend token handling.
- **Excluded Scope**: External production servers, live cloud resources.
- **Files Inspected**: `backend/src/main.ts`, `backend/src/auth/auth.service.ts`, `backend/src/auth/jwt.strategy.ts`, `docker-compose.yml`, `nginx.conf`, `backend/.env`.
- **Commands Executed**: `git rev-parse HEAD`, `git branch --show-current`, `git status --short --branch`.
- **Commands Blocked**: Live vulnerability scanners requiring active servers.
- **Audit Limitations**: Evaluated via OWASP-aligned static code inspection.

---

## Domain Overview & Confirmed Strengths
- **Security Middleware**: NestJS initializes `helmet` security headers in `main.ts` and global `ValidationPipe` with `whitelist: true` and `forbidNonWhitelisted: true`.
- **Throttling**: `@nestjs/throttler` configured to mitigate brute-force attacks on REST endpoints.

---

## Findings

## SEC-001

### Title
Insecure Default Hardcoded JWT Secret Key Fallback in Production Configuration

### Domain
Security

### Category
Cryptographic Failures & Hardcoded Credentials

### Severity
HIGH

### Confidence
CONFIRMED

### Status
OPEN

### Affected Application
NestJS Backend (`backend/`)

### Affected Files
- `backend/src/auth/auth.module.ts`
- `backend/src/auth/jwt.strategy.ts`

### Relevant Symbols or Lines
- `backend/src/auth/jwt.strategy.ts#L10-L15`

### Evidence
In `jwt.strategy.ts`:
```typescript
secretOrKey: process.env.JWT_SECRET || 'super-secret-key-canina'
```

### Problem
If the `JWT_SECRET` environment variable is omitted or fails to load in deployment, the server silently falls back to a publicly known hardcoded secret string (`'super-secret-key-canina'`).

### Root Cause
Defensive fallback string provided for `JWT_SECRET` instead of crashing on startup when mandatory environment variables are missing.

### Why It Matters
Attackers can forge arbitrary JWT tokens with any user ID or role (`User_PetOwner` / `Admin`) to bypass authentication completely if the secret falls back to default.

### User or Business Impact
Total unauthorized access to user accounts, order history, pet medical records, and admin endpoints.

### Technical Impact
Complete compromise of authentication signature validation.

### Security or Data-Integrity Impact
High severity authentication bypass.

### Recommended Direction
Throw an explicit startup error if `process.env.JWT_SECRET` is undefined or less than 32 characters in length. Remove hardcoded fallback strings.

### Alternative Direction
Use NestJS `ConfigService` with mandatory schema validation (Joi or Zod).

### Implementation Complexity
LOW

### Dependencies
None.

### Risks
Deployment will fail to start if `JWT_SECRET` is not set in `.env` (intended security behavior).

### Verification Requirements
Unset `JWT_SECRET` in environment and verify NestJS backend refuses to start up.

### Testing Requirements
Unit test JWT module initialization without `JWT_SECRET`.

### Acceptance Criteria
Backend startup terminates with an explicit error when `JWT_SECRET` is absent.

### Notes and Limitations
Environment variable names referenced without printing actual secret values.

---

## SEC-002

### Title
Predictable Deterministic Pseudo-Random Generation of One-Time Passwords (OTP)

### Domain
Security

### Category
Identification & Authentication Failures

### Severity
HIGH

### Confidence
CONFIRMED

### Status
OPEN

### Affected Application
NestJS Backend (`backend/`)

### Affected Files
- `backend/src/auth/auth.service.ts`

### Relevant Symbols or Lines
- `backend/src/auth/auth.service.ts#L19` (`sendOtp`)

### Evidence
In `AuthService.sendOtp`:
```typescript
const code = Math.floor(10000 + Math.random() * 90000).toString();
```

### Problem
Uses `Math.random()` to generate 5-digit authentication OTP codes. `Math.random()` is not a cryptographically secure random number generator (CSPRNG) and its PRNG internal seed state can be predicted after observing sequential outputs.

### Root Cause
Use of standard Math library instead of Node.js native `crypto.randomInt` or `crypto.getRandomValues`.

### Why It Matters
An attacker can predict valid OTP verification codes generated for arbitrary user phone numbers, enabling unauthorized login.

### User or Business Impact
Account takeover of any customer account by predicting their SMS OTP code.

### Technical Impact
Cryptographic weakness in identity verification.

### Security or Data-Integrity Impact
High risk of account hijacking.

### Recommended Direction
Replace `Math.random()` with `crypto.randomInt(10000, 100000).toString()`.

### Alternative Direction
Use Node.js `crypto.randomBytes`.

### Implementation Complexity
LOW

### Dependencies
Node.js `crypto` built-in module.

### Risks
None.

### Verification Requirements
Verify OTP generation utilizes `crypto.randomInt`.

### Testing Requirements
Unit test `sendOtp` method using crypto CSPRNG.

### Acceptance Criteria
OTP codes are generated using cryptographically secure random entropy.

### Notes and Limitations
None.

---

## Finding Summary
- **CRITICAL**: 0
- **HIGH**: 2
- **MEDIUM**: 0
- **LOW**: 0
- **INFO**: 0

- **CONFIRMED**: 2
- **HIGH_CONFIDENCE**: 0
- **NEEDS_VERIFICATION**: 0
- **SPECULATIVE**: 0

## Completion Statement
Security audit completed. 2 HIGH severity findings confirmed.