CVE-2025-11637

Executive Summary

CVE-2025-11637 is a race condition vulnerability in the Tomofun Furbo 360 pet camera, specifically in firmware version FB0035_FW_036. The flaw resides in the Audio Handler component, allowing an unauthenticated remote attacker to exploit a race condition, potentially leading to denial of service or unauthorized audio stream manipulation. The vendor has not responded to disclosure, leaving the device unpatched. This vulnerability poses a risk to home privacy and device availability.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in an IoT device.

CVSS Breakdown & Threat Level

CVSS Score: 0.0 (No official vector assigned) Given the remote attack vector and lack of authentication, a reasonable CVSS v3.1 vector would be: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L (Base Score: 3.7, Low)

• Attack Vector (AV): Network (remote exploitation possible)
• Attack Complexity (AC): High (race condition requires precise timing)
• Privileges Required (PR): None
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): None
• Integrity (I): None
• Availability (A): Low (potential denial of service)

Threat Level: Low to Medium. Exploitation is complex but could disrupt device functionality.

Deep Dive & Mechanics

The vulnerability is a race condition in the Audio Handler component of the Furbo 360 firmware. The Audio Handler manages audio streams for two-way communication. A race condition occurs when multiple threads or processes access shared resources (e.g., audio buffers, device state) without proper synchronization. An attacker can send specially crafted network packets to trigger concurrent operations, causing the handler to enter an inconsistent state. This could lead to:

• Denial of Service (DoS): The audio subsystem crashes or becomes unresponsive.
• Audio Manipulation: Potential for unauthorized audio injection or interception.

The attack is remote, meaning the attacker only needs network access to the device (e.g., via the local network or internet if exposed). No authentication is required.

Vulnerable vs. Patched Code

No patched code is available. The vulnerable code is in the firmware binary (FB0035_FW_036). A hypothetical vulnerable code snippet might look like:

// Vulnerable: No mutex protection
void audio_handler_process_packet(packet_t *pkt) {
    static audio_buffer_t *buf = NULL;
    if (pkt->type == AUDIO_START) {
        buf = allocate_buffer();
    }
    if (buf != NULL) {
        // Race condition: multiple threads can write simultaneously
        write_to_buffer(buf, pkt->data, pkt->len);
    }
}

A patched version would use a mutex:

// Patched: Mutex protection
static mutex_t audio_mutex;
void audio_handler_process_packet(packet_t *pkt) {
    static audio_buffer_t *buf = NULL;
    mutex_lock(&audio_mutex);
    if (pkt->type == AUDIO_START) {
        buf = allocate_buffer();
    }
    if (buf != NULL) {
        write_to_buffer(buf, pkt->data, pkt->len);
    }
    mutex_unlock(&audio_mutex);
}

Exploitation & Lab Setup

Red Team

Objective: Exploit the race condition to cause a denial of service.

Lab Setup:

• Furbo 360 device with firmware FB0035_FW_036
• Attacker machine (Kali Linux)
• Network connectivity (same LAN or WAN if device is exposed)

Exploitation Steps:

1. Identify the device IP (e.g., via nmap).
2. Craft multiple concurrent network packets targeting the Audio Handler. Use a tool like hping3 or a custom Python script.
3. Send packets in rapid succession to trigger the race condition.

Example Python script (conceptual):

import socket
import threading

target_ip = "192.168.1.100"
target_port = 8080  # Example port

def send_packet():
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    payload = b"\x00" * 100  # Crafted packet
    sock.sendto(payload, (target_ip, target_port))
    sock.close()

threads = []
for _ in range(100):
    t = threading.Thread(target=send_packet)
    threads.append(t)
    t.start()

for t in threads:
    t.join()

Expected Outcome: Device audio functionality becomes unresponsive.

Blue Team

Objective: Detect and mitigate exploitation attempts.

Detection:

• Monitor for a high volume of packets to the Audio Handler port within a short time window.
• Use network intrusion detection systems (NIDS) to flag anomalous traffic patterns.

Mitigation:

• Isolate the device on a separate VLAN.
• Disable remote access if not needed.
• Apply network rate limiting to the device's port.

Indicators of Compromise (IOCs)

• Network: High frequency of UDP packets to port 8080 (or the device's audio port) from a single source.
• Device: Audio subsystem crashes or becomes unresponsive.
• Logs: Repeated error messages in device logs related to audio buffer overflows or thread deadlocks.

Detection Engineering

YARA Rule

rule CVE_2025_11637_Furbo_RaceCondition {
    meta:
        description = "Detects Furbo 360 firmware with race condition vulnerability"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-11637"
    strings:
        $firmware = "FB0035_FW_036"
        $audio_handler = "audio_handler_process_packet"
    condition:
        $firmware or $audio_handler
}

Sigma Rule

title: Furbo 360 Audio Handler Race Condition Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects multiple rapid packets to Furbo 360 audio port
author: Valters IT
date: 2025-04-10
logsource:
    category: network
    product: suricata
detection:
    selection:
        dest_port: 8080
        protocol: udp
    condition: selection | count() by src_ip > 50 within 1 second
falsepositives:
    - Legitimate audio streaming bursts
level: medium

Suricata Rule

alert udp any any -> $HOME_NET 8080 (msg:"CVE-2025-11637 Furbo 360 Audio Race Condition Attempt"; flow:to_server; threshold: type both, track by_src, count 50, seconds 1; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Place the Furbo 360 on a separate VLAN with restricted access.
2. Disable remote access: If not required, block inbound connections to the device from the internet.
3. Monitor network traffic: Use the provided Suricata/Sigma rules to detect exploitation attempts.

Long-term:

• Contact Tomofun for a firmware patch. Since the vendor is unresponsive, consider replacing the device with a more secure alternative.
• Implement network segmentation for all IoT devices.

Valters IT
Securing Digital Frontiers