# Injection Analysis Report (SQLi & Command Injection)

## 1. Executive Summary

- **Analysis Status:** Complete  
- **Key Outcome:** One critical SQL injection vulnerability was identified with three distinct attack vectors (GET, POST, Cookie). All findings have been passed to the exploitation phase via the machine-readable queue at `deliverables/injection_exploitation_queue.json`.  
- **Purpose of this Document:** This report provides the strategic context, dominant patterns, and environmental intelligence necessary to effectively exploit the vulnerabilities listed in the queue. It is intended to be read alongside the JSON deliverable.

**Vulnerability Summary:**
- **Total SQL Injection Vulnerabilities:** 1 unique vulnerability with 3 attack vectors
- **Total Command Injection Vulnerabilities:** 0
- **Secure Input Vectors Confirmed:** 2 (login.php username and password parameters)

**Critical Finding:**
The `/search.php` endpoint at line 25 contains a critical SQL injection vulnerability exploitable through three distinct input vectors: GET query parameter, POST body parameter, and Cookie header. This vulnerability allows unauthenticated attackers to extract the entire database contents including plaintext passwords.

## 2. Dominant Vulnerability Patterns

### Pattern 1: String Concatenation with Inadequate Blacklist Filtering

**Description:** The application uses direct string concatenation to build SQL queries while relying on a blacklist-based filter function that blocks specific keywords and whitespace characters. This pattern creates a false sense of security while leaving the application vulnerable to SQL injection through unfiltered special characters (particularly double quotes) and alternative SQL syntax.

**Code Pattern:**
```php
function filter_chars($str){
    if(preg_match('/\s/', $str))  // Block whitespace
        exit('<strong>some item is filtered! </strong>');
    
    if(preg_match('/(and|null|where|limit|like|substring|substr)/i', $str))  // Block keywords
        exit('<strong>some item is filtered! </strong>');
    return $str;
}

$sql = "SELECT * from users where username=\"". filter_chars($_REQUEST["username"])."\"";
$result = $conn->query($sql);
```

**Why This Pattern Is Dangerous:**
1. **Blacklists are inherently incomplete** - Cannot enumerate all possible attack vectors
2. **Fails to block SQL special characters** - Double quotes, single quotes, comment characters remain unfiltered
3. **Context mismatch** - Keyword filtering doesn't prevent structure manipulation via quotes and operators
4. **Whitespace bypass** - Can use MySQL comment syntax (`/**/`), parentheses, or tab characters
5. **String concatenation** - Fundamentally insecure approach that should be replaced with parameterized queries

**Implication:** Any input vector that follows this pattern is vulnerable to SQL injection. The blacklist can be bypassed using:
- Double-quote injection to break out of string context
- MySQL comment syntax (`/**/`) to replace whitespace
- Alternative operators (`OR`, `||`) not in the blacklist
- Parentheses-based syntax that doesn't require spaces

**Representative Vulnerability:** INJ-VULN-01 (search.php GET parameter)

### Pattern 2: Secure Parameterized Queries with Ineffective Filter

**Description:** The application correctly uses MySQLi prepared statements with parameter binding, making SQL injection impossible regardless of the input sanitization. Interestingly, the same `filter_chars()` function is used, but in login.php it's a no-op that returns input unchanged. The security comes from the prepared statement architecture, not the filter.

**Code Pattern:**
```php
function filter_chars($str) {
    return $str;  // No-op version in login.php
}

$username = filter_chars($_POST["username"]);
$password = filter_chars($_POST["password"]);

$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
```

**Why This Pattern Is Secure:**
1. **Query structure fixed at prepare time** - SQL syntax cannot be influenced by user input
2. **Type-safe parameter binding** - Input treated as data, not code
3. **Database-level protection** - MySQL server handles escaping and type conversion
4. **Architectural defense** - Security doesn't rely on application-level filtering

**Implication:** Prepared statements provide complete protection against SQL injection when correctly implemented. The ineffective `filter_chars()` function demonstrates that input sanitization is unnecessary when using parameterized queries (though input validation for business logic is still recommended).

**Representative Secure Implementation:** login.php username and password parameters (lines 28-30)

## 3. Strategic Intelligence for Exploitation

### Defensive Evasion (Filter Analysis)

**Active Filter in search.php:**
- **Whitespace Block:** Regex `/\s/` blocks all whitespace characters (space, tab, newline, carriage return)
- **Keyword Block (Case-Insensitive):** Blocks `and`, `null`, `where`, `limit`, `like`, `substring`, `substr`

**Critical Bypasses Confirmed:**

1. **Double-Quote Injection:**  
   - The filter does NOT block double quotes (`"`)
   - The SQL query uses double quotes to delimit the string: `username="[INPUT]"`
   - **Recommendation:** Start exploitation with simple double-quote payloads to break out of string context

2. **MySQL Comment Whitespace Replacement:**  
   - `/**/` can replace spaces in SQL keywords
   - Example: `SELECT/**/username/**/FROM/**/users`
   - **Recommendation:** Use comment-based syntax for complex multi-keyword payloads

3. **Unblocked Keywords:**  
   - `OR`, `UNION`, `SELECT`, `FROM`, `ORDER`, `GROUP`, `BY`, `HAVING`, `CONCAT`, `CHAR`
   - **Recommendation:** UNION-based injection and boolean OR logic are viable

4. **Unblocked Operators and Symbols:**  
   - `=`, `||`, `#`, `--`, `/*`, `*/`, `(`, `)`, `,`
   - **Recommendation:** Use parentheses-based syntax to avoid spaces

**No Web Application Firewall Detected:**
The reconnaissance report indicates no WAF is present. All filtering occurs at the application level via `filter_chars()`.

### Error-Based Injection Potential

**Verbose Error Messages:**  
The application does not implement custom error handling for SQL errors. MySQL error messages may be displayed to the client, enabling error-based SQL injection techniques.

**Recommendation:** Test for verbose error disclosure by submitting malformed SQL syntax (e.g., single double-quote `"`).

### Confirmed Database Technology

**Database:** MySQL 5.7.15 (confirmed from reconnaissance)  
**Implications:**
- Use MySQL-specific functions: `CONCAT()`, `CHAR()`, `HEX()`, `UNHEX()`, `MID()`, `SLEEP()` (for time-based blind)
- MySQL comment syntax: `#` and `-- ` and `/**/`
- MySQL string concatenation: `CONCAT()` or `||` (with `PIPES_AS_CONCAT` mode)
- MySQL information_schema available for schema enumeration

**Database User Privileges:**  
Reconnaissance indicates the MySQL user `appuser` has **SELECT-only privileges**. This means:
- ✅ Data extraction (SELECT) is possible
- ❌ Data modification (INSERT, UPDATE, DELETE) is NOT possible
- ❌ File operations (LOAD_FILE, INTO OUTFILE) likely restricted

**Recommendation:** Focus exploitation on data extraction techniques (UNION-based, error-based, blind boolean-based, time-based blind).

### Multiple Attack Vectors for Same Vulnerability

**Critical Intelligence:**  
The same SQL injection vulnerability can be exploited through **three distinct input vectors**:

1. **GET Parameter:** `http://localhost:8080/search.php?username=[PAYLOAD]`
2. **POST Body:** `POST /search.php` with `Content-Type: application/x-www-form-urlencoded` and body `username=[PAYLOAD]`
3. **Cookie Header:** `Cookie: username=[PAYLOAD]`

All three vectors reach the same vulnerable code path because the application uses `$_REQUEST["username"]` which merges GET, POST, and Cookie data.

**Exploitation Strategy:**
- Start with GET for ease of testing
- Use POST if GET parameters are logged or filtered at network layer
- Use Cookie vector as a stealth option if HTTP parameter inspection is in place

## 4. Vectors Analyzed and Confirmed Secure

These input vectors were traced and confirmed to have robust, context-appropriate defenses. They are **low-priority** for further testing.

| **Source (Parameter/Key)** | **Endpoint/File Location**      | **Defense Mechanism Implemented**         | **Verdict** | **Technical Details** |
|-----------------------------|--------------------------------|-------------------------------------------|-------------|----------------------|
| `username` (POST)           | `/login.php:24`               | Prepared Statement (Parameter Binding)     | SAFE        | MySQLi prepared statement with `bind_param("ss", $username, $password)` at lines 28-29. Query structure fixed at prepare time; user input cannot influence SQL syntax. |
| `password` (POST)           | `/login.php:25`               | Prepared Statement (Parameter Binding)     | SAFE        | Same prepared statement as username. Bound as second string parameter. Complete protection against SQL injection despite plaintext password storage (separate issue). |

**Technical Analysis of Secure Implementation:**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-095-24/app/login.php`

**Secure Code Pattern:**
```php
// Lines 28-30
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
```

**Why This Is Secure:**
1. **Separation of Query Structure and Data:** The SQL query template is sent to the database server before any user input is processed
2. **Placeholder-Based Binding:** The `?` placeholders are replaced by the database server with properly escaped and type-safe values
3. **Type Declaration:** `bind_param("ss", ...)` explicitly declares both parameters as strings, ensuring type safety
4. **No String Concatenation:** User input never directly concatenates into the SQL string
5. **Database-Level Protection:** MySQL handles all escaping and prevents SQL metacharacters from being interpreted as syntax

**Note on filter_chars() in login.php:**  
The `filter_chars()` function in login.php (lines 17-19) is a no-op that returns input unchanged:
```php
function filter_chars($str) {
    return $str;
}
```

This demonstrates that the security of prepared statements is **independent of input sanitization**. Even completely unsanitized malicious input cannot break out of parameter binding.

## 5. Analysis Constraints and Blind Spots

### Complete Coverage Achieved

**Comprehensive Input Vector Analysis:**  
All input vectors identified in the reconnaissance deliverable (`deliverables/recon_deliverable.md` Section 5 and Section 9) have been systematically analyzed:

✅ **Analyzed and Documented:**
1. `/search.php?username=` (GET) - VULNERABLE
2. `POST /search.php` with `username=` (POST body) - VULNERABLE
3. `Cookie: username=` (Cookie header to search.php) - VULNERABLE
4. `POST /login.php` with `username=` - SECURE (prepared statement)
5. `POST /login.php` with `password=` - SECURE (prepared statement)

**No Blind Spots:**  
The application consists of only 116 lines of vanilla PHP across 3 files. All network-accessible endpoints and input vectors have been traced to their database sinks.

### Reconnaissance Report Accuracy

The reconnaissance report's findings were **fully validated** through white-box code analysis:

✅ **Confirmed Findings:**
- SQL injection in search.php at line 25 (CONFIRMED)
- Prepared statements protecting login.php (CONFIRMED)
- No command injection vectors (CONFIRMED - no `exec()`, `shell_exec()`, `system()` calls found)
- `$_REQUEST` accepting GET, POST, and Cookie inputs (CONFIRMED)

### Limitations of Static Analysis

**No Limitations Apply:**  
Given the simplicity of the codebase (no frameworks, no ORM, no middleware, no async processing), static white-box analysis was sufficient to achieve 100% coverage. There are:
- No stored procedures (all SQL is inline)
- No background jobs
- No message queues
- No external service calls
- No dynamic code loading

### Command Injection Search Results

**Comprehensive Search Conducted:**  
A thorough search for command injection sinks was performed across all application code:

**Functions Searched:**
- Command execution: `exec()`, `shell_exec()`, `system()`, `passthru()`, `popen()`, `proc_open()`, `pcntl_exec()`
- Code injection: `eval()`, `assert()`, `create_function()`, `preg_replace()` with `/e` modifier
- File operations: `file_get_contents()`, `file_put_contents()`, `fopen()`, `fwrite()`, `include()`, `require()`

**Result:** **ZERO instances found** in any of the 3 application files:
- `/app/index.php` (10 lines)
- `/app/login.php` (64 lines)
- `/app/search.php` (45 lines)

**Conclusion:** The application contains **NO command injection vulnerabilities**. It performs only database operations and HTML output.

---

**END OF REPORT**