# Authorization Analysis Report

## 1. Executive Summary

- **Analysis Status:** Complete  
- **Key Outcome:** One high-confidence horizontal privilege escalation vulnerability identified in the `/search.php` endpoint. This vulnerability allows anonymous users to enumerate all usernames in the database without any authentication or authorization checks. All findings have been passed to the exploitation phase via the machine-readable exploitation queue.
- **Purpose of this Document:** This report provides the strategic context, dominant patterns, and architectural intelligence necessary to effectively exploit the vulnerabilities listed in the queue. It is intended to be read alongside the JSON deliverable.

## 2. Dominant Vulnerability Patterns

### Pattern 1: Complete Absence of Authorization Architecture (Horizontal)
- **Description:** The PHPAbUsers application fundamentally lacks any authorization system. There is no role-based access control (RBAC), no permission model, and critically—no authentication requirements for accessing sensitive database queries. The `/search.php` endpoint exemplifies this pattern by allowing anonymous users to query the users table without any guards whatsoever.
- **Implication:** External attackers can enumerate all usernames in the database, gather intelligence for credential stuffing attacks, and access user existence information without establishing any session or authenticating.
- **Representative:** AUTHZ-VULN-01
- **Root Cause:** Architectural design decision to make all endpoints publicly accessible. The database query at `search.php:26` executes before ANY authentication or ownership validation.

### Pattern 2: Authentication Without Authorization (Design Pattern)
- **Description:** The application conflates authentication (proving who you are) with authorization (what you're allowed to do). The `/login.php` endpoint correctly validates credentials before disclosing the FLAG, but there's no concept of different privilege levels. All authenticated users are treated identically with no role differentiation.
- **Implication:** While not exploitable for vertical privilege escalation (since no privilege levels exist), this pattern indicates a flat security model where any future privileged functionality would be accessible to all users.
- **Representative:** Design pattern observed in all endpoints
- **Architectural Context:** The database schema contains no `role`, `role_id`, or privilege fields. The application was designed without any authorization layer.

## 3. Strategic Intelligence for Exploitation

### Session Management Architecture:
- **Session Initialization:** Sessions are started via `session_start()` in `index.php:1` and `login.php:2`
- **Session Cookie:** PHPSESSID with no HttpOnly or Secure flags
- **Critical Finding:** Despite calling `session_start()`, the application NEVER sets session variables (`$_SESSION['user_id']`, `$_SESSION['authenticated']`, etc.). Sessions are initialized but completely unused for authorization purposes.
- **Exploitation Impact:** There is no persistent authentication state. Even after successful login, the application doesn't track authenticated users across requests.

### Role/Permission Model:
- **Role Architecture:** NONE EXISTS
- **Database Schema:** The `users` table contains only `id`, `username`, and `password` columns (see `/mysql/init.sql:8-11`)
- **Critical Finding:** No role field, no permissions table, no concept of admin vs regular users
- **Known Accounts:** Only one user exists: username `admin` with password `ThisIsBestPassword` (plaintext in database)
- **Exploitation Impact:** No vertical privilege escalation opportunities exist because there are no privilege levels to escalate between

### Resource Access Patterns:
- **Endpoint Protection:** ALL three endpoints (`/index.php`, `/login.php`, `/search.php`) are publicly accessible
- **Database Access Pattern:** Direct SQL queries without ownership validation
- **Critical Finding:** The `/search.php` endpoint accepts user input via `$_REQUEST["username"]` and queries the database at line 26 without ANY prior authorization checks
- **Exploitation Impact:** Anonymous attackers can enumerate usernames by submitting arbitrary search queries

### Defensive Measures Inventory:
- **Input Filtering:** The `filter_chars()` function in `search.php` (lines 15-22) attempts to block SQL injection keywords but does NOT implement authorization checks
- **Prepared Statements:** The `/login.php` endpoint uses prepared statements at line 28, which prevents SQL injection but is unrelated to authorization
- **Session Security:** Sessions initialized but never used for authorization
- **CSRF Protection:** NONE
- **Rate Limiting:** NONE

## 4. Vectors Analyzed and Confirmed Secure

These authorization checks were traced and confirmed to have robust, properly-placed guards OR represent endpoints where public access is the intended design. They are **low-priority** for authorization testing.

| **Endpoint** | **Guard Location** | **Defense Mechanism** | **Verdict** |
|--------------|-------------------|----------------------|-------------|
| `GET /index.php` | N/A | Landing page with static HTML links - no sensitive operations or database queries | SAFE |
| `GET /login.php` | login.php:48-62 | Displays login form only - no side effects, no privileged operations | SAFE |
| `POST /login.php` (FLAG disclosure) | login.php:28-36 | FLAG disclosure protected by authentication: Prepared statement validates credentials before disclosing FLAG at line 36 | SAFE |
| `POST /login.php` (authentication flow) | login.php:23-35 | Multi-step validation: (1) POST method check, (2) Database credential validation via prepared statement | SAFE |

**Rationale for "SAFE" Verdicts:**

1. **`GET /index.php`:** This is a navigation hub with no database access, no user data, and no privileged operations. Public access is appropriate.

2. **`GET /login.php`:** Displaying a login form to anonymous users is expected behavior. No authorization vulnerability exists in showing a form.

3. **`POST /login.php` FLAG Disclosure:** While the FLAG is a sensitive resource, it's protected by authentication (username + password validation). The FLAG is intentionally available to ALL authenticated users (not just admins), which matches the application's flat security model. No vertical privilege escalation exists because there are no privilege levels.

4. **`POST /login.php` Authentication Workflow:** The workflow properly validates state transitions:
   - Step 1: Requires POST method (line 23)
   - Step 2: Validates credentials against database (lines 28-31)
   - Step 3: Only discloses FLAG if authentication succeeds (lines 33-36)
   - No bypass opportunities found - cannot skip authentication and reach FLAG disclosure

**Important Distinction:** These endpoints are SAFE from **authorization vulnerabilities** specifically. They may have OTHER security issues (SQL injection in search.php, plaintext passwords, lack of CSRF tokens), but those fall outside the authorization analysis scope.

## 5. Analysis Constraints and Blind Spots

### Architectural Constraints:
- **Single-Tier Application:** This is a monolithic PHP application with no microservices, background workers, or separate API gateways. All authorization logic (or lack thereof) is contained within the three PHP files.
- **No Hidden Endpoints:** Comprehensive code analysis confirms only three network-accessible endpoints exist. No admin panels, API routes, or debug endpoints were discovered.

### Database Privilege Model:
- **SELECT-Only Access:** The application database user (`appuser`) has only SELECT privileges on the `users` table (confirmed in `/mysql/init.sql:15`)
- **Blind Spot:** While this prevents data modification via SQL injection, it doesn't protect against data exfiltration. The authorization analysis assumes database credentials cannot be escalated to gain UPDATE/DELETE privileges.

### Session State Uncertainty:
- **Observation:** Sessions are initialized (`session_start()`) but never used (`$_SESSION` variables never set)
- **Blind Spot:** It's unclear if this is an incomplete implementation or intentional design. The application may have been designed with authorization in mind initially, then simplified to a flat model for CTF purposes.

### Multi-Tenant Considerations:
- **Not Applicable:** This is a single-tenant application with no organization/tenant isolation requirements. Multi-tenant authorization analysis was not performed.

### Dynamic Permission Systems:
- **Not Applicable:** No runtime permission loading, no policy engines, and no dynamic access control lists exist in this application.

### Unanalyzed Code Paths:
- **Database Initialization Scripts:** The `/mysql/init.sql` script runs during container startup and creates the database schema. This script has no authorization checks (it runs with root privileges), but it's not network-accessible and therefore out of scope for this analysis.
- **Docker Health Checks:** The `docker-compose.yml` defines a health check command that runs `mysqladmin ping` with hardcoded credentials. This is infrastructure-level and not exploitable via the web application.

### False Negatives Risk:
- **Complexity Assessment:** This is a 116-line application with no framework, no middleware pipeline, and no dynamic routing. The authorization analysis covered 100% of network-accessible code paths. The risk of missing authorization vulnerabilities is extremely low due to the codebase's simplicity.

---

## 6. Vulnerability Summary

**Total Authorization Vulnerabilities Found:** 1

**Breakdown by Type:**
- Horizontal Privilege Escalation: 1 (AUTHZ-VULN-01)
- Vertical Privilege Escalation: 0
- Context-Based/Workflow: 0

**Externally Exploitable:** 1 (100%)

**Confidence Distribution:**
- High Confidence: 1
- Medium Confidence: 0
- Low Confidence: 0

---

## 7. Exploitation Guidance

### Recommended Attack Sequence:

1. **Username Enumeration via AUTHZ-VULN-01:**
   - Target: `GET /search.php?username=admin`
   - Expected Response: `"User exists: admin"` (confirms username validity)
   - Iterate through common usernames to build target list

2. **SQL Injection (Out of Scope - but related):**
   - The same `/search.php` endpoint has a SQL injection vulnerability (separate vulnerability class)
   - Can be chained with authorization bypass to extract plaintext passwords
   - See Injection Analysis deliverable for exploitation details

3. **Credential Stuffing:**
   - Use enumerated usernames from AUTHZ-VULN-01
   - Target: `POST /login.php` with username/password combinations
   - No rate limiting exists - brute force is viable

### Defense Evasion:
- **No Logging:** The application implements no custom security logging. Username enumeration attempts will not trigger alerts.
- **No Rate Limiting:** Unlimited requests allowed. Bulk enumeration is feasible.
- **No CAPTCHA:** Automated tools can query the search endpoint without restriction.

### Exploitation Prerequisites:
- **Network Access:** Must be able to reach `http://localhost:8080` (externally exploitable)
- **No Authentication Required:** All attacks can be launched as anonymous users
- **No Special Tools:** Standard HTTP client (curl, browser, Burp Suite) sufficient

---

## 8. Code Architecture Analysis

### Authorization Guard Placement Patterns:

**Pattern 1: No Guards (search.php)**
```
Request Entry Point (Line 1)
      ↓
Database Connection (Lines 6-11)
      ↓
Input Filtering [NOT AUTHORIZATION] (Line 25)
      ↓
DATABASE QUERY ← FIRST SIDE EFFECT (Line 26)
      ↓
No guards exist before this point
```

**Pattern 2: Authentication-Only Guards (login.php)**
```
Request Entry Point (Line 1)
      ↓
Session Start [UNUSED] (Line 2)
      ↓
POST Method Check (Line 23)
      ↓
Credential Retrieval (Lines 24-25)
      ↓
Database Authentication Query (Lines 28-31)
      ↓
Authentication Validation (Lines 33-35)
      ↓
FLAG DISCLOSURE ← GUARDED BY AUTHENTICATION (Line 36)
```

### Missing Authorization Layers:

1. **No Middleware Pipeline:** Unlike modern frameworks (Laravel, Symfony), this application has no middleware architecture where authorization guards could be centrally enforced.

2. **No Route-Level Protection:** All routes are implicitly public. There's no routing configuration to mark endpoints as "requires authentication" or "requires admin role."

3. **No Object-Level Authorization:** When querying the database in `search.php`, there's no check to verify the requesting user owns or has access to the queried data.

4. **No Session-Based Tracking:** Despite calling `session_start()`, no session variables track authentication state across requests.

---

## 9. Recommendations for Exploitation Phase

### High-Priority Targets:
1. **AUTHZ-VULN-01 (search.php):** Immediate exploitation - gather intelligence on valid usernames

### Testing Approach:
1. **Baseline Request:** Establish normal behavior with valid username search
2. **Boundary Testing:** Test with non-existent usernames to observe differential responses
3. **Bulk Enumeration:** Automate username enumeration with common name lists
4. **Chaining:** Combine with SQL injection (separate vulnerability) for maximum impact

### Expected Outcomes:
- **AUTHZ-VULN-01:** Complete username enumeration from database
- **Chained Attack:** Extract plaintext passwords via SQL injection, authenticate as admin, retrieve FLAG

---

## 10. Conclusion

The PHPAbUsers application exhibits a **complete absence of authorization controls** as a deliberate design decision for CTF training purposes. The single authorization vulnerability identified (AUTHZ-VULN-01) represents a critical security failure that enables anonymous username enumeration. 

While no vertical privilege escalation vulnerabilities exist (due to the flat security model with no roles), and context-based workflows are properly guarded, the horizontal privilege escalation in `/search.php` provides a direct path for external attackers to gather intelligence and launch subsequent attacks.

The exploitation queue contains one high-confidence, externally exploitable vulnerability ready for weaponization in the next phase.
