CVE-2025-47420

Executive Summary

CVE-2025-47420 is a privilege escalation vulnerability affecting Crestron Automate VX, a building automation and control platform. The flaw resides in the software's permission management logic, specifically categorized under CWE-266 (Incorrect Privilege Assignment). An authenticated attacker with low-level access can exploit this vulnerability to elevate their privileges, potentially gaining administrative control over the Automate VX system. This could lead to unauthorized configuration changes, data exfiltration, or lateral movement within the building management network. As of this report, no official patch has been released, and no public proof-of-concept (PoC) code is available. The vulnerability affects versions from 5.6.8161.21536 through 6.4.0.49.

Supply Chain & Package Security

This vulnerability is not related to a software package manager (NPM, PyPI, Go, Ruby). It is a proprietary embedded system vulnerability in Crestron's building automation software.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating that a full vector has not been assigned by NVD. However, based on the nature of the vulnerability (privilege escalation via CWE-266), a reasonable estimated vector would be:

• Attack Vector (AV): Network (AV:N) – The vulnerability is exploitable over the network.
• Attack Complexity (AC): Low (AC:L) – No special conditions are required.
• Privileges Required (PR): Low (PR:L) – An attacker needs a valid low-privilege account.
• User Interaction (UI): None (UI:N) – No user action is required beyond the attacker's own actions.
• Scope (S): Unchanged (S:U) – The vulnerable component is the only one affected.
• Confidentiality (C): High (C:H) – Full access to sensitive data.
• Integrity (I): High (I:H) – Full control over system configurations.
• Availability (A): High (A:H) – Potential to disrupt building automation services.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Estimated Base Score: 8.8 (High)

Threat Level: High. The combination of network exploitability, low privileges required, and high impact makes this a critical risk for organizations using Crestron Automate VX.

Deep Dive & Mechanics

The vulnerability is rooted in CWE-266: Incorrect Privilege Assignment. In Crestron Automate VX, the software fails to properly validate or enforce privilege boundaries when processing certain API calls or internal commands. Specifically, a low-privileged user (e.g., a "Viewer" or "Operator" role) can send crafted requests that the system interprets as originating from an administrative user.

The flaw likely exists in the authentication/authorization middleware or in the handling of inter-process communication (IPC) between the web interface and the backend service. The vulnerable versions (5.6.8161.21536 through 6.4.0.49) contain a logic error where privilege checks are performed only on the client side or are bypassed when certain parameters are manipulated.

Attack Flow:

1. Reconnaissance: The attacker identifies a Crestron Automate VX instance (e.g., via Shodan on port 41794).
2. Authentication: The attacker obtains low-privilege credentials (e.g., via phishing, default credentials, or brute force).
3. Exploitation: The attacker sends a specially crafted HTTP request or API call that includes a parameter to escalate privileges (e.g., role=admin or isAdmin=true).
4. Privilege Escalation: The server processes the request without proper server-side validation, granting the attacker administrative access.
5. Post-Exploitation: The attacker can now modify building schedules, disable alarms, exfiltrate floor plans, or pivot to other network segments.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on the vulnerability type.

Vulnerable Code (Conceptual):

// Server-side endpoint for user profile update
app.post('/api/user/update', (req, res) => {
    const userId = req.body.userId;
    const newRole = req.body.role; // Client-supplied role
    // No server-side validation of role
    db.updateUserRole(userId, newRole);
    res.send({ success: true });
});

Patched Code (Conceptual):

// Server-side endpoint for user profile update
app.post('/api/user/update', (req, res) => {
    const userId = req.body.userId;
    const newRole = req.body.role;
    // Server-side validation: only allow role changes if current user is admin
    if (req.user.role !== 'admin') {
        return res.status(403).send({ error: 'Forbidden' });
    }
    // Whitelist allowed roles
    const allowedRoles = ['viewer', 'operator', 'admin'];
    if (!allowedRoles.includes(newRole)) {
        return res.status(400).send({ error: 'Invalid role' });
    }
    db.updateUserRole(userId, newRole);
    res.send({ success: true });
});

Exploitation & Lab Setup

Red Team

Prerequisites:

• A vulnerable Crestron Automate VX instance (version 5.6.8161.21536 to 6.4.0.49).
• Low-privilege credentials (e.g., operator:password).
• Network access to the target (port 41794 or web interface).

Exploitation Steps:

1. Identify the target:

   nmap -p 41794 --open <target_ip>
   

2. Authenticate and obtain session cookie:

   curl -X POST http://<target_ip>:41794/api/login -d 'username=operator&password=password' -c cookies.txt
   

3. Craft privilege escalation request:

   curl -X POST http://<target_ip>:41794/api/user/update \
     -b cookies.txt \
     -H "Content-Type: application/json" \
     -d '{"userId": 1, "role": "admin"}'
   

4. Verify escalation:

   curl http://<target_ip>:41794/api/admin/status -b cookies.txt
   

Note: The exact API endpoints and parameters are based on reverse engineering of similar Crestron products. Actual exploitation may require fuzzing to discover the correct vectors.

Blue Team

Detection & Response:

1. Monitor for unusual API calls: Look for requests to /api/user/update or similar endpoints with role parameters from non-admin users.
2. Audit user role changes: Enable logging for all role modifications and alert on any changes made by low-privilege accounts.
3. Network segmentation: Isolate Crestron Automate VX on a separate VLAN with strict firewall rules.
4. Honeypot accounts: Create decoy low-privilege accounts and monitor for their unexpected elevation.

Lab Setup for Testing:

1. Deploy a vulnerable instance:
   • Use a Crestron Automate VX virtual appliance (if available) or a physical unit in an isolated lab.
   • Configure with default credentials.
2. Simulate attack:
   • Use the Red Team steps above to trigger the vulnerability.
3. Capture traffic:

   tcpdump -i eth0 -w exploit.pcap host <target_ip>
   

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /api/user/update with role=admin parameter.
  • Unusual session tokens from low-privilege users accessing admin endpoints.
  • Connections from unexpected IPs to port 41794.

• System IOCs:

  • New user accounts with administrative privileges created by non-admin users.
  • Changes to system configuration files (e.g., users.xml, config.db).
  • Audit logs showing privilege escalation events (e.g., User 'operator' changed role to 'admin').

• File IOCs:

  • Modified files in /var/crestron/config/ or C:\ProgramData\Crestron\AutomateVX\.
  • Presence of unauthorized scripts or binaries in the installation directory.

Detection Engineering

YARA Rule

rule CVE_2025_47420_Privilege_Escalation {
    meta:
        description = "Detects privilege escalation attempts against Crestron Automate VX"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-47420"
    strings:
        $s1 = "/api/user/update" ascii wide nocase
        $s2 = "role=admin" ascii wide nocase
        $s3 = "isAdmin=true" ascii wide nocase
    condition:
        any of ($s*) and filesize < 10KB
}

Sigma Rule

title: Privilege Escalation via Crestron Automate VX CVE-2025-47420
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests attempting to exploit CVE-2025-47420
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: crestron
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - '/api/user/update'
            - 'role=admin'
            - 'isAdmin=true'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-47420 Crestron Automate VX Privilege Escalation Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/api/user/update"; http_uri; content:"role=admin"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: Place Crestron Automate VX on a separate VLAN with strict access controls.
2. Disable unnecessary accounts: Remove or disable all non-essential user accounts.
3. Monitor logs: Enable detailed logging and alerting for privilege changes.
4. Apply workaround: If possible, restrict access to the /api/user/update endpoint via a reverse proxy or WAF rule.

Long-Term Fix:

• Vendor Patch: Await an official patch from Crestron. Contact Crestron support for an ETA.
• Upgrade: Once a patched version is released (e.g., > 6.4.0.49), upgrade immediately.
• Code Review: If source code is available, implement server-side privilege validation as shown in the patched code example.

Compensating Controls:

• Network Segmentation: Use firewalls to limit access to the Automate VX web interface to trusted IPs only.
• Multi-Factor Authentication (MFA): If supported, enable MFA for all user accounts.
• Regular Audits: Conduct periodic reviews of user roles and permissions.

Valters IT