CVE-2026-24347

Executive Summary

CVE-2026-24347 is a critical security advisory affecting the EZCast Pro II device, specifically firmware version 1.17478.146. The vulnerability resides in the Admin UI and is classified as an Improper Input Validation (CWE-20) flaw. This allows an attacker to manipulate files within the /tmp directory of the device. While the CVSS score is listed as 0.0 (likely unassigned or placeholder), the potential impact is significant as it could lead to arbitrary file writes, privilege escalation, or denial of service. The vendor, Ezcast, has not released a patch, and no public proof-of-concept (PoC) or exploit code is available at this time. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains for exposed devices.

CVSS Breakdown & Threat Level

The CVSS score is currently listed as 0.0, which is likely a placeholder or unassigned value. Based on the vulnerability description, a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N) – The Admin UI is accessible over the network.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Requires admin-level access to the UI.
• User Interaction (UI): None (N) – No user interaction needed.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): High (H) – Files in /tmp can be manipulated.
• Availability (A): Low (L) – Could lead to denial of service.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:L

Threat Level: High (due to integrity impact and lack of patch).

Deep Dive & Mechanics

The vulnerability is an improper input validation flaw in the Admin UI of the EZCast Pro II device. The Admin UI likely accepts user-supplied input (e.g., file paths, filenames, or configuration parameters) without proper sanitization. This allows an attacker with admin credentials to craft requests that write, modify, or delete files in the /tmp directory.

The /tmp directory is typically used for temporary files, but on embedded devices, it may contain critical system files, logs, or configuration data. An attacker could:

• Overwrite temporary configuration files to alter device behavior.
• Create symlinks to other sensitive files (e.g., /etc/passwd) to escalate privileges.
• Write malicious scripts that are executed by other processes.
• Cause a denial of service by filling the filesystem.

The attack vector is network-based, requiring access to the Admin UI (usually on port 80 or 443). Since the vulnerability is unpatched, any device running version 1.17478.146 is at risk.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be made. However, based on the vulnerability type, the vulnerable code likely resembles:

# Vulnerable code (pseudo)
def save_temp_file(filename, content):
    path = "/tmp/" + filename
    with open(path, "w") as f:
        f.write(content)

The patched code would include input validation:

# Patched code (pseudo)
import os
import re

def save_temp_file(filename, content):
    # Validate filename: only allow alphanumeric and underscore
    if not re.match(r'^[a-zA-Z0-9_]+$', filename):
        raise ValueError("Invalid filename")
    path = os.path.join("/tmp", filename)
    # Ensure path is within /tmp
    if not path.startswith("/tmp/"):
        raise ValueError("Invalid path")
    with open(path, "w") as f:
        f.write(content)

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• Network access to the EZCast Pro II Admin UI (e.g., http://<device-ip>/admin).
• Valid admin credentials (default credentials may be admin:admin or similar).

Exploitation Steps:

1. Identify the vulnerable endpoint: Use a web proxy (e.g., Burp Suite) to intercept requests from the Admin UI. Look for endpoints that handle file operations (e.g., /admin/save_temp, /admin/upload).

2. Craft a malicious request: Send a POST request with a manipulated filename to write to /tmp.

   POST /admin/save_temp HTTP/1.1
   Host: <device-ip>
   Content-Type: application/x-www-form-urlencoded
   Cookie: <session_cookie>
   
   filename=../../etc/passwd&content=malicious_data
   

   This attempts a path traversal to write outside /tmp. If successful, it could overwrite system files.

3. Verify the attack: Check if the file was created or modified by accessing the device via SSH or other means.

Note: Since no public exploit exists, this is a theoretical approach.

Blue Team (Defender)

Detection and Response:

1. Monitor Admin UI logs: Look for unusual file operations or requests with suspicious filenames (e.g., containing ../ or special characters).

2. File integrity monitoring: Use tools like AIDE or Tripwire to monitor changes in /tmp and other critical directories.

3. Network segmentation: Isolate EZCast devices on a separate VLAN with strict access controls.

4. Honeypot: Deploy a fake /tmp file to detect unauthorized writes.

Indicators of Compromise (IOCs)

• File paths: /tmp/* files with unexpected names or content.
• Network traffic: HTTP requests to /admin/save_temp or similar endpoints with unusual parameters.
• System logs: Entries indicating file creation or modification in /tmp by the admin user.
• Processes: Unusual processes spawned from /tmp (e.g., scripts executed from there).

Detection Engineering

YARA Rule

rule CVE_2026_24347_EZCast_Pro_II_File_Manipulation {
    meta:
        description = "Detects attempts to manipulate files in /tmp via Admin UI on EZCast Pro II"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-24347"
        hash = "unknown"
    strings:
        $s1 = "/tmp/" ascii wide nocase
        $s2 = "filename=" ascii wide nocase
        $s3 = "content=" ascii wide nocase
        $s4 = "../" ascii wide nocase
    condition:
        all of ($s1, $s2, $s3) or ($s1 and $s4)
}

Sigma Rule

title: CVE-2026-24347 - EZCast Pro II Admin UI File Manipulation
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests to the EZCast Pro II Admin UI that attempt to manipulate files in /tmp
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-24347
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/admin/save_temp'
        cs-uri-query|contains: 'filename='
    condition: selection
falsepositives:
    - Legitimate admin file operations
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-24347 - EZCast Pro II Admin UI File Manipulation Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/admin/save_temp"; http_uri; content:"filename="; http_client_body; pcre:"/filename=[^&]*\.\.\//i"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote access to the Admin UI if not required.
2. Change default credentials to strong, unique passwords.
3. Apply network segmentation to limit access to the device.
4. Monitor logs for suspicious activity.

Long-term Fix:

• Since no patch is available, contact Ezcast support for a firmware update.
• Consider replacing the device if no patch is released.

Workaround:

• Implement a web application firewall (WAF) rule to block requests with path traversal patterns (e.g., ../).

Report generated by Valters IT DevSecOps & CTI Division. This analysis is based on available data and should be verified with live testing.