CVE-2024-8510

Executive Summary

CVE-2024-8510 is a path traversal vulnerability in N-able N-central, a remote monitoring and management (RMM) platform. The flaw allows an unauthenticated attacker to access the Apache Tomcat WEB-INF directory, potentially exposing configuration files and application internals. While customer data is not directly exposed, the vulnerability can aid in reconnaissance for further attacks. The CVSS score is 5.3 (Medium), and the EPSS probability is 0.0%, indicating low active exploitation. The vendor has released a fix in N-central 2024.6.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.3 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: None
• Availability Impact: None

The threat level is medium due to the low complexity and network-based attack vector, but the impact is limited to information disclosure of non-customer data.

Deep Dive & Mechanics

The vulnerability resides in the N-central web application, which runs on Apache Tomcat. A path traversal flaw in the application's request handling allows an attacker to use ../ sequences to navigate outside the intended web root and access the WEB-INF directory. This directory contains critical configuration files, such as web.xml, which may reveal database credentials, API keys, or internal network paths. The attack is performed via HTTP GET requests with crafted URL parameters.

The root cause is insufficient input validation of file paths in the application's servlet or filter logic. The application fails to sanitize user-supplied input that specifies file paths, allowing directory traversal.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// Vulnerable: Directly uses user input to construct file path
String filePath = request.getParameter("file");
File file = new File("/var/www/n-central/" + filePath);
// No validation of filePath for ".." sequences

Patched Code (Conceptual):

// Patched: Validates and sanitizes the file path
String filePath = request.getParameter("file");
if (filePath != null && filePath.contains("..")) {
    throw new SecurityException("Path traversal detected");
}
// Or use a whitelist of allowed files

The patch in N-central 2024.6 implements proper input validation and canonical path checks to prevent directory traversal.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target running N-central prior to version 2024.6
• Network access to the N-central web interface (typically port 443 or 8443)

Exploitation Steps:

1. Identify the N-central web interface.
2. Craft a GET request to traverse to the WEB-INF directory:

   GET /..;/..;/WEB-INF/web.xml HTTP/1.1
   Host: target-ncentral.example.com
   

   Or using URL encoding:

   GET /%2e%2e/%2e%2e/WEB-INF/web.xml HTTP/1.1
   Host: target-ncentral.example.com
   

3. Analyze the response for configuration data.

Expected Output:

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
    <display-name>N-central</display-name>
    <!-- Sensitive configuration -->
</web-app>

Blue Team

Detection:

• Monitor web server logs for requests containing ../, %2e%2e, or WEB-INF in the URL.
• Alert on HTTP 200 responses to requests for WEB-INF or META-INF directories.

Hunting:

• Search for anomalous GET requests with path traversal patterns in the last 30 days.
• Correlate with known N-central versions.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing ../ or %2e%2e targeting N-central web interface.
  • Access to /WEB-INF/ or /META-INF/ paths.
• File System IOCs:
  • Unexpected access to web.xml or server.xml files.
• Log IOCs:
  • Tomcat access logs showing GET /..;/..;/WEB-INF/ entries.

Detection Engineering

YARA Rule

rule CVE_2024_8510_Path_Traversal {
    meta:
        description = "Detects path traversal attempts targeting N-central WEB-INF directory"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-8510"
    strings:
        $traversal1 = "..\\"
        $traversal2 = "../"
        $traversal3 = "%2e%2e/"
        $traversal4 = "WEB-INF"
        $traversal5 = "META-INF"
    condition:
        any of ($traversal*) and #traversal4 > 0 or #traversal5 > 0
}

Sigma Rule

title: CVE-2024-8510 N-central Path Traversal Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests attempting to exploit path traversal in N-central
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-8510
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - '..\\'
            - '../'
            - '%2e%2e/'
            - 'WEB-INF'
            - 'META-INF'
    condition: selection
falsepositives:
    - Legitimate file paths containing 'WEB-INF' (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-8510 N-central Path Traversal Attempt"; flow:to_server,established; content:"GET"; http_method; content:"..\\"; http_uri; nocase; content:"../"; http_uri; nocase; content:"%2e%2e/"; http_uri; nocase; content:"WEB-INF"; http_uri; nocase; content:"META-INF"; http_uri; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade N-central to version 2024.6 or later.
2. If immediate upgrade is not possible, implement a WAF rule to block path traversal patterns:

   RewriteEngine On
   RewriteCond %{REQUEST_URI} (\.\.|%2e%2e|WEB-INF|META-INF) [NC]
   RewriteRule .* - [F,L]
   

3. Restrict network access to the N-central web interface to trusted IPs only.

Long-term Measures:

• Conduct regular security audits of web applications.
• Implement input validation and canonical path checks in all file access functions.
• Monitor for similar CVEs in N-able products.

Valters IT - DevSecOps & Cyber Threat Intelligence Expert