CVE-2025-24345

Executive Summary

CVE-2025-24345 is a vulnerability in the “Hosts” functionality of the web application component of ctrlX OS. A remote authenticated attacker with low privileges can manipulate the system’s hosts file via a crafted HTTP request. This allows the attacker to redirect network traffic, bypass security controls, or facilitate further attacks such as man-in-the-middle (MITM) or domain hijacking. The CVSS score is 6.3 (Medium), with a vector indicating network access, low complexity, low privileges required, no user interaction, and a high impact on integrity. No public proof-of-concept or exploit code is available, and the vendor has not released a patch.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects the ctrlX OS web application, which is a proprietary component of the ctrlX ecosystem.

CVSS Breakdown & Threat Level

• CVSS Score: 6.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: High (I:H)
• Availability Impact: None (A:N)

The threat level is medium due to the requirement for authentication, but the potential for integrity compromise is high. An attacker can manipulate DNS resolution, leading to traffic redirection and further compromise.

Deep Dive & Mechanics

The vulnerability exists in the “Hosts” functionality of the ctrlX OS web application. This feature allows administrators to manage the system’s hosts file for local DNS resolution. The application fails to properly validate or sanitize user input when processing HTTP requests to modify the hosts file. A low-privileged authenticated attacker can craft a malicious HTTP request that injects arbitrary entries into the hosts file.

The hosts file is a critical system file that maps hostnames to IP addresses. By adding malicious entries, an attacker can redirect traffic intended for legitimate services to attacker-controlled servers. This can be used to:

• Bypass network security controls.
• Perform man-in-the-middle attacks.
• Steal credentials or sensitive data.
• Disrupt services.

The attack does not require any special privileges beyond a low-level authenticated session, making it a significant risk in multi-tenant or shared environments.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the current implementation of the “Hosts” functionality in ctrlX OS. The patched code would include input validation and sanitization to ensure that only valid, non-malicious entries are written to the hosts file.

Vulnerable Code (Conceptual):

def update_hosts(hostname, ip_address):
    with open('/etc/hosts', 'a') as f:
        f.write(f"{ip_address} {hostname}\n")

Patched Code (Conceptual):

import re

def update_hosts(hostname, ip_address):
    # Validate IP address format
    if not re.match(r'^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$', ip_address):
        raise ValueError("Invalid IP address")
    # Validate hostname format
    if not re.match(r'^[a-zA-Z0-9.-]+$', hostname):
        raise ValueError("Invalid hostname")
    with open('/etc/hosts', 'a') as f:
        f.write(f"{ip_address} {hostname}\n")

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a ctrlX OS instance with a low-privileged account.
• Network connectivity to the web application.

Exploitation Steps:

1. Authenticate to the ctrlX OS web application with low-privileged credentials.
2. Identify the endpoint for modifying the hosts file (e.g., /api/hosts).
3. Craft a POST request with a malicious payload to add a new hosts entry:

   POST /api/hosts HTTP/1.1
   Host: target-ctrlx
   Content-Type: application/json
   Authorization: Bearer <token>
   
   {
     "hostname": "malicious.com",
     "ip_address": "192.168.1.100"
   }
   

4. Verify the entry is added to the hosts file by attempting to resolve the hostname.

Expected Outcome: The attacker can redirect traffic for malicious.com to 192.168.1.100.

Blue Team

Detection Steps:

1. Monitor for unauthorized modifications to the hosts file using file integrity monitoring (FIM).
2. Alert on any changes to /etc/hosts that are not part of a known change management process.
3. Review web application logs for suspicious API calls to the hosts endpoint.
4. Implement strict input validation on the server side to prevent injection.

Hunting Queries:

• Search for HTTP requests to /api/hosts with unusual IP addresses or hostnames.
• Look for patterns of multiple hosts file modifications in a short time.

Indicators of Compromise (IOCs)

• File Modification: /etc/hosts file contains unexpected entries.
• Network Traffic: DNS queries for unusual hostnames that resolve to internal IPs.
• Log Entries: Web application logs showing POST requests to /api/hosts with suspicious payloads.
• Processes: Unusual processes reading or writing to /etc/hosts.

Detection Engineering

YARA Rule

rule ctrlx_hosts_manipulation {
    meta:
        description = "Detects manipulation of hosts file via ctrlX OS web app"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-24345"
    strings:
        $s1 = "/etc/hosts" ascii wide
        $s2 = "POST /api/hosts" ascii wide
        $s3 = "ip_address" ascii wide
        $s4 = "hostname" ascii wide
    condition:
        any of ($s*) and #s1 > 0
}

Sigma Rule

title: ctrlX OS Hosts File Manipulation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to modify the hosts file via ctrlX OS web application
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-24345
logsource:
    category: webserver
    product: ctrlx
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/api/hosts'
    condition: selection
falsepositives:
    - Legitimate administrative actions
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-24345 ctrlX OS Hosts File Manipulation"; flow:to_server; content:"POST"; http_method; content:"/api/hosts"; http_uri; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict access to the ctrlX OS web application to trusted networks only.
2. Implement strong authentication and authorization controls.
3. Monitor and audit changes to the hosts file.

Long-term Fix:

• Apply vendor patch when available.
• Implement input validation and sanitization for all user-supplied data.
• Use file integrity monitoring to detect unauthorized changes.

Workarounds:

• Disable the “Hosts” functionality if not required.
• Use a read-only filesystem for critical system files.

Valters IT
Securing Digital Frontiers