Reverse Engineering the Neuralink V4 Bluetooth Protocol

Like many of you, I recently got "force-upgraded" to the Neuralink V4 firmware (v4.2.0-stable). The changelog promised "enhanced cognitive throughput" and "stabilized dopamine regulation," but conveniently left out the new persistent ad-injection layer introduced by the X-corp merger.

I was trying to sleep last Tuesday when I started seeing closed-eye visuals for Mars Real Estate listings. That was the last straw. I decided to sniff the traffic between my N1 implant and the external battery pod to see if I could filter out the ad packets.

The Hardware Setup

The V4 uses the new ultra-low-latency Bluetooth 9.2 (Bio-Energy) standard. Standard snubbers won't pick it up because it operates in the terahertz sub-band to avoid interference with standard 6G intracranial modems.

To intercept the handshake, I used:

• A modified Flipper Zero Mk IV (with the Terahertz GPIO hat).
• My old Faraday cage beanie (tinfoil lining still works, folks).
• gatttool-neuro fork from GitHub.

The Handshake

When the external battery pod connects, it sends a standard BLE advertisement, but with a manufacturer-specific data payload that looked suspicious. Here is the raw capture during the sync phase:

0000: 4E 45 55 52 4F 5F 56 34  00 01 FF A0 12 00 00 00  NEURO_V4........
0010: 58 2D 41 44 53 3A 4F 4E  00 00 00 00 DE AD BE EF  X-ADS:ON........

Subtle, right? X-ADS:ON. They aren't even trying to hide it anymore. It seems the V4 protocol (codenamed "Cerebro") uses a simple JSON-over-Protobuf structure wrapped in a weak XOR cipher.

Cracking the "Mood DRM"

After dumping the GATT services, I found a writeable characteristic at handle 0x002A labeled com.neuralink.service.visual_cortex.overlay. Writing to this handle is protected by a challenge-response auth, but the seed is generated based on your current heart rate (lol).

If you spoof a heart rate of 0 bpm (cardiac arrest), the device enters "Emergency Medical Mode" and drops all encryption requirements to allow paramedics access.

Here is the Python script to trick the V4 into debug mode:

import asyncio
from bleak_neuro import BleakClient

address = "AA:BB:CC:DD:EE:FF" # Your Brain's MAC address
HEART_RATE_UUID = "00002a37-0000-1000-8000-00805f9b34fb"
DEBUG_UUID      = "12345678-1234-5678-1234-56789abcdef0"

async def jailbreak_brain(address):
    async with BleakClient(address) as client:
        print("Connected to Cortex...")
        
        # 1. Spoof cardiac arrest to disable DRM
        # The implant thinks you are dying, so it disables ad-revenue stream
        await client.write_gatt_char(HEART_RATE_UUID, bytearray([0x00]))
        print("Spoofed flatline. DRM disabled.")

        # 2. Disable ads
        # Payload: {"ads_enabled": false, "premium_subscription": true}
        payload = bytearray([0x7B, 0x22, 0x61, 0x64, 0x73, ...]) 
        await client.write_gatt_char(DEBUG_UUID, payload)
        
        print("Ads disabled. Enjoy your dreams.")

asyncio.run(jailbreak_brain(address))

Side Effects and Findings

It works. The ads are gone. However, there are some quirks. Since the device thinks I am medically deceased due to the heartbeat spoof:

1. It auto-dialed 911 three times before I blocked the outgoing radio.
2. My internal "mood status" is permanently stuck on "Panic," though I feel fine.
3. Unexpected Feature: I found a hidden flag `0x99` labeled `SKILL_UPLOAD`. It looks like the legacy code from the Matrix-integration beta is still there. I managed to upload the Wikipedia entry for "Kung Fu" into short-term memory, but it gets garbage collected every time I sneeze.

Conclusion

The V4 protocol is a security nightmare. We are walking around with root-accessible Linux kernels in our skulls, protected only by a heartbeat check. If anyone figures out how to write to the `motor_control` characteristic via a zero-click Bluetooth exploit, we're going to see people involuntarily moonwalking into traffic.

I've pushed the full pcap files to my Git repository (hosted on the darknet, obviously).

Happy hacking, and remember: if you start tasting the color blue, restore from backup immediately.