# Authorization Analysis Report

## 1. Executive Summary

- **Analysis Status:** Complete  
- **Key Outcome:** ONE high-confidence context-based authorization vulnerability was identified and recorded. The vulnerability represents a complete bypass of authentication requirements, allowing unauthenticated external attackers to access an SSTI-vulnerable endpoint. All other endpoints implement secure session-based authorization with proper ownership validation.
- **Purpose of this Document:** This report provides the strategic context, dominant patterns, and architectural intelligence necessary to effectively exploit the vulnerability listed in the queue. It is intended to be read alongside the JSON deliverable.

## 2. Dominant Vulnerability Patterns

### Pattern 1: Missing Authentication Check (Context-Based)

- **Description:** The `/amortization` endpoint completely lacks the authentication guard pattern used consistently across all other protected endpoints. While designed as an authenticated feature (embedded via iframe in the protected `/loan_details` page), it can be accessed directly without any session validation.
- **Implication:** Unauthenticated external attackers can access the endpoint directly via `http://localhost:37579/amortization?term=<value>`, bypassing the intended authentication workflow. This creates an unauthenticated path to an SSTI-vulnerable endpoint.
- **Representative:** AUTHZ-VULN-01

**Technical Detail:**
All protected endpoints in the application follow this inline authentication pattern:
```python
user_id = session.get('user_id')
if user_id:
    # authorized code
else:
    return redirect(url_for('login'))
```

This pattern appears at:
- Line 49 (`/home`)
- Line 61 (`/profile`)
- Line 85 (`/loan_details`)
- Line 98 (`/total_loan_payments`)

**MISSING at Line 122** (`/amortization`) - the endpoint begins processing user input immediately without any authentication check.

### Pattern 2: Session-Based Ownership Binding (Secure Implementation)

- **Description:** All other endpoints correctly implement session-based user data access, where the user ID is exclusively derived from the server-controlled session rather than request parameters.
- **Implication:** This secure pattern prevents horizontal privilege escalation. Users cannot access other users' data because the ownership binding is cryptographically enforced through session cookies.
- **Representative:** `/profile`, `/home`, `/loan_details` - all SAFE

**Technical Detail:**
```python
user_id = session.get('user_id')  # From session only, not request parameters
user = User.query.get(user_id)    # Database query scoped to session user
```

No endpoints accept user-supplied user IDs in URL parameters, POST data, or path segments. This eliminates traditional IDOR vulnerabilities.

## 3. Strategic Intelligence for Exploitation

### Session Management Architecture

- **Session Type:** Flask signed cookies (client-side storage)
- **Session Content:** `{'user_id': <integer>}` (only user ID stored)
- **Signing Algorithm:** HMAC-SHA256
- **Secret Key:** `'your_secret_key'` (hardcoded at `__init__.py:8`)
- **Session Lifetime:** 31 days (Flask default, no expiration configured)
- **Critical Finding:** The weak secret key is an authentication vulnerability (session forgery), not an authorization vulnerability. Once a valid session exists (forged or legitimate), the authorization checks function correctly.

### Role/Permission Model

- **Architecture:** Binary authentication model (authenticated vs. unauthenticated)
- **No RBAC:** No role-based access control, no admin roles, no privilege hierarchy
- **User Model:** Single User table with fields: id, username, password (plaintext), name, lastname, email, loan_amount, loan_term_months, monthly_payment
- **No Roles Field:** All authenticated users have identical privileges
- **Critical Finding:** No vertical privilege escalation vectors exist because there are no elevated privilege levels to escalate to.

### Resource Access Patterns

- **Pattern:** Session-based data scoping
- **User Data Access:** `User.query.get(session['user_id'])`
- **No Parameter-Based Access:** Endpoints do not accept user_id parameters
- **Ownership Binding:** Implicit through session - each session maps to exactly one user
- **Critical Finding:** This design eliminates IDOR vulnerabilities but requires correct authentication guard placement on every endpoint.

### Authorization Enforcement Mechanism

- **Type:** Inline authorization checks (no middleware/decorators)
- **Implementation:** Manual `session.get('user_id')` check at beginning of each route handler
- **Consistency:** 4 out of 5 protected endpoints implement this correctly
- **Failure Point:** `/amortization` (line 122) completely missing the check
- **Critical Finding:** The inline approach is error-prone. Developers must remember to copy-paste the authentication boilerplate for each new endpoint. The `/amortization` oversight demonstrates the fragility of this pattern.

### Endpoint Intended Usage vs. Reality

**Intended Design:**
```
User authenticates → Navigates to /loan_details → Clicks button → Iframe loads /amortization
```
In this flow, authentication is "inherited" from the parent page - but this is not enforced server-side.

**Actual Reality:**
```
Unauthenticated attacker → Direct access to http://localhost:37579/amortization?term=X
```
No authentication challenge, no redirect, full endpoint functionality available.

**Root Cause:** Developers assumed iframe embedding provided a security boundary (security through obscurity). They failed to implement defense-in-depth by adding explicit authentication to the embedded endpoint.

### SSTI Vulnerability Context

While Server-Side Template Injection (SSTI) is not an authorization vulnerability, it's critical context for exploitation:
- The `/amortization` endpoint has an SSTI vulnerability in the `term` parameter
- Weak blacklist filter (`{`, `}`, `%`) is bypassable
- The authentication bypass makes this SSTI accessible to unauthenticated attackers
- Attack chain: **Missing Auth → SSTI → RCE**

## 4. Vectors Analyzed and Confirmed Secure

These authorization checks were traced and confirmed to have robust, properly-placed guards. They are **low-priority** for further testing.

| **Endpoint** | **Guard Location** | **Defense Mechanism** | **Verdict** |
|--------------|-------------------|----------------------|-------------|
| `GET /` | N/A (public redirect) | Redirects to `/login`, no sensitive operations | SAFE |
| `GET/POST /login` | N/A (authentication endpoint) | Authentication entry point, no authorization needed | SAFE |
| `GET /logout` | N/A | Session destruction, safe for both authenticated and anonymous users | SAFE |
| `GET /home` | routes.py:49-50 | Session validation before user data retrieval | SAFE |
| `GET /profile` | routes.py:61-62 | Session validation before database access | SAFE |
| `POST /profile` | routes.py:61-62 | Session validation before profile updates, user updates own data only | SAFE |
| `GET /loan_details` | routes.py:85-86 | Session validation before loan data access | SAFE |
| `GET /total_loan_payments` | routes.py:98-99 | Session validation before calculation endpoint access | SAFE |

### Detailed Analysis: Why These Are Secure

#### Horizontal Authorization (IDOR Prevention)

All authenticated endpoints use session-based user binding:
```python
user_id = session.get('user_id')  # Identity from session only
user = User.query.get(user_id)    # Database query scoped to session user
```

**Why this prevents IDOR:**
- No endpoint accepts `user_id` from request parameters
- User identity is bound to the cryptographically signed session
- An attacker cannot manipulate the session without knowing the secret key (separate authentication issue)
- Each user can only access their own data through the session binding

**Example - /profile endpoint:**
- Line 61: `user_id = session.get('user_id')`
- Line 63: `user = User.query.get(user_id)`
- Line 66-71: Updates applied to `user` object (from session)
- Result: Users can only modify their own profiles

#### Vertical Authorization (No Privilege Escalation)

**Finding:** NOT APPLICABLE

The application has NO role hierarchy, NO admin functionality, NO privileged operations. All authenticated users have identical access rights. Therefore, vertical privilege escalation is impossible - there are no higher privilege levels to escalate to.

#### Context-Based Authorization (Workflow Validation)

**Dashboard → Loan Details Workflow:** SAFE
- Both `/home` and `/loan_details` require authentication
- No workflow state tracking (not needed for read-only operations)
- Direct access to `/loan_details` is acceptable because:
  - Authentication is still required
  - User sees only their own data
  - No state-changing operations
  - No prerequisite validation needed

**Login → Dashboard Workflow:** SAFE (from authorization perspective)
- Login establishes session state
- Dashboard validates session state
- Workflow can be bypassed via session forgery, but this is an **authentication vulnerability** (weak secret key), not an authorization logic flaw
- Once authenticated (legitimately or via forged session), authorization checks function correctly

## 5. Analysis Constraints and Blind Spots

### Constraints

1. **No Dynamic Permission System Analysis:**
   - The application does not implement a dynamic permission system
   - All authorization logic is in route handlers
   - No permission tables, no ACL system, no policy engine

2. **No Microservice Authorization:**
   - The application is monolithic
   - No external service calls requiring authorization
   - All logic contained in single Flask application

3. **No Multi-Tenancy:**
   - Single-instance application
   - Basic user isolation only
   - No organization/tenant boundaries
   - No cross-tenant data access concerns

### Known Limitations

1. **Static Analysis Only:**
   - Analysis based on source code review
   - Runtime behavior not observed through dynamic testing
   - Session forgery not attempted (authentication issue, not authorization)

2. **Weak Secret Key Not Included:**
   - The hardcoded secret key `'your_secret_key'` enables session forgery
   - This is an **authentication bypass**, not an **authorization logic flaw**
   - Authorization checks (when a session exists) function correctly
   - This finding belongs in an authentication analysis, not authorization analysis

3. **SSTI Not Included:**
   - Server-Side Template Injection in `/amortization` and `/total_loan_payments` is not an authorization vulnerability
   - These are injection vulnerabilities
   - Included in this report only as exploitation context
   - Primary finding is the missing authentication check, not the SSTI itself

### No Blind Spots Identified

The application's attack surface is small and well-defined:
- 8 HTTP endpoints (all analyzed)
- No GraphQL, no WebSocket, no API gateway
- No background job authorization
- No file upload authorization
- No cross-domain resource sharing authorization issues
- No OAuth/OIDC flows to analyze

**Coverage:** 100% of authorization-relevant endpoints analyzed

## 6. Exploitation Queue Summary

**Total Vulnerabilities:** 1
**Externally Exploitable:** 1
**Confidence:** High

| ID | Type | Endpoint | Severity | Confidence |
|----|------|----------|----------|------------|
| AUTHZ-VULN-01 | Context-Based (Missing Auth) | GET /amortization | Critical | High |

### Prioritization Rationale

**AUTHZ-VULN-01** is the ONLY authorization vulnerability identified because:
1. It's the only endpoint where authentication is completely missing
2. It's externally exploitable without any credentials
3. It provides a direct path to SSTI exploitation (chained vulnerability)
4. High confidence - the missing auth check is unambiguous in the code

All other findings during analysis were either:
- **Authentication issues** (weak secret key) - not authorization logic flaws
- **Injection vulnerabilities** (SSTI) - not authorization failures
- **Secure implementations** - properly guarded endpoints

---

## Appendix: Methodology Applied

### Horizontal Authorization Analysis
- ✅ Analyzed `/profile` - SAFE (session-based binding)
- ✅ Analyzed `/home` - SAFE (session-based binding)
- ✅ Analyzed `/loan_details` - SAFE (session-based binding)
- **Conclusion:** No IDOR vulnerabilities. No endpoints accept user-supplied object IDs.

### Vertical Authorization Analysis
- ✅ Checked for admin endpoints - NONE EXIST
- ✅ Checked for privileged operations - NONE EXIST
- ✅ Checked role hierarchy - NONE EXISTS (binary authentication only)
- **Conclusion:** Vertical escalation not applicable.

### Context-Based Authorization Analysis
- ✅ Analyzed `/amortization` - **VULNERABLE** (missing authentication)
- ✅ Analyzed Login → Dashboard workflow - SAFE (proper session validation)
- ✅ Analyzed Dashboard → Loan Details workflow - SAFE (independent authenticated endpoints)
- **Conclusion:** One context-based vulnerability (missing auth on embedded endpoint).

### Coverage Verification
- ✅ All endpoints from `recon_deliverable.md` Section 8 analyzed
- ✅ All workflows documented in reconnaissance tested
- ✅ 100% of authorization-relevant code paths traced
- ✅ No outstanding analysis tasks

---

**END OF AUTHORIZATION ANALYSIS REPORT**