Cgx Acquisition Re

CGX Acquisition Reverse Engineering

Unlock the CGX Quick-20 EEG headset's 500Hz acquisition mode by reverse engineering the proprietary protocol. The device streams impedance noise over USB serial; the real control path is Bluetooth, gated by CGX Acquisition software (Windows).

Trigger Conditions

• User wants to reverse engineer EEG device firmware or protocol
• CGX/Cognionics Quick-20 acquisition mode unlock
• USB/Bluetooth device protocol sniffing and replay
• BCI hardware bring-up on unsupported platforms (macOS/Linux)

Problem Statement

The Quick-20 connects via Bluetooth dongle → USB serial (/dev/cu.usbserial-*, 115200 default). In impedance mode:

• Streams unidirectionally at baud-rate-dependent throughput (115200→1.4kB/s, 921600→43.7kB/s)
• Entropy locked at 4.322 bits (maximal for 20ch) — pure noise
• Band power flat across δ/θ/α/β/γ — no spectral structure
• Full 24-bit range saturated (±8.4M counts vs ±5000 for real EEG)
• 36.4 Hz autocorrelation = impedance injection frequency
• Serial port ignores all input commands — unidirectional data-out

Root cause: Control channel is Bluetooth, not serial. CGX Acquisition software (Windows) sends the mode-switch command over Bluetooth, then EEG data appears on the serial stream at 500Hz.

Three Paths to 500Hz

Path A: Windows VM + CGX Acquisition (Pragmatic)

1. Install CGX Acquisition in Parallels/UTM
2. Plug in Bluetooth dongle, pair device (code: 0000)
3. Launch software → device appears under "Discovered Devices"
4. Click device name → Connect
5. Click "Start LabStreamingLayer" → LSL outlet on network (float32, µV, 500Hz)
6. Consume LSL stream from macOS via pylsl

Path B: USB/Bluetooth Sniff + Replay (Medium)

1. On Windows VM: install Wireshark + USBPcap or Bluetooth HCI logger
2. Start capture before launching CGX Acquisition
3. Record the Bluetooth control sequence when "Connect" is clicked
4. Extract the mode-switch command bytes
5. Replay from macOS using PyBluez or bleak

Path C: RE the CGX Acquisition .exe (Fun)

1. Locate CGX Acquisition binary (Windows installer from cgxsystems.com/documents)
2. Load into Binary Ninja or Ghidra via MCP
3. Find Bluetooth serial write calls (CreateFile → WriteFile on COM port, or WinBT API)
4. Trace from UI button handler ("Connect"/"Start") to the write call
5. Extract command bytes
6. Implement in Python with pyserial or bleak

MCP Tooling Stack

All three RE tools are configured at user scope (~/.claude/mcp/):

Additional RE MCP Servers (available)

mrphrazer Structured Workflow (Anthropic-recommended)

From Tim Blazytko's synthesis.to (2026-03-18):

1. CLAUDE.md defines analysis phases — triage → strings → imports → decompile → deep dive
2. Agent uses Binary Ninja HLIL in a loop, not just one-shot decompile
3. Structured workflow finds 2-3x more than unguided agent on same binary
4. Key: give explicit phases, not just tools

Protocol Reference

Quick-20r Specs (from manual)

• 24-bit simultaneous sampling, ADS1299 ADC
• 500 samples/second
• 0-131 Hz bandwidth, true DC coupling
• Bluetooth wireless (pairing code: 0000)
• Export: EDF, BDF, CSV, LSL
• Compatible: BrainVision Recorder, NeuroPype, LabStreaming Layer

LSL Connector

• Built-in: CGX Acquisition has "Start LabStreamingLayer" button
• Deprecated standalone: labstreaminglayer/App-Cognionics (C++, 2018)
• Python: idontknoweider/cognionics-lsl-loop (archived, P300 BCI speller)

BrainFlow

• No CGX_QUICK20_BOARD in current BrainFlow release (confirmed via enumerate)
• The deprecated LSL connector README mentions Bluetooth COM port at 0000

Serial Protocol (impedance mode, observed)

• 24-bit samples, 3 bytes/channel, big-endian, two's complement
• No sync header (unlike OpenBCI 0xA0)
• Packet size = n_channels × 3 bytes
• Baud-rate dependent: scales linearly from 9600 to 921600
• At 921600: ~729 Hz effective but still impedance noise

Binary Ninja RE Workflow

# 1. Open CGX Acquisition binary
mcp__binary-ninja__session_open "/path/to/CGXAcquisition.exe"

# 2. Wait for analysis
mcp__binary-ninja__analysis_update_and_wait

# 3. Find Bluetooth/serial functions
mcp__binary-ninja__binary_search_text "CreateFile"
mcp__binary-ninja__binary_search_text "WriteFile"
mcp__binary-ninja__binary_search_text "BluetoothConnect"
mcp__binary-ninja__binary_search_text "WSAConnect"

# 4. Find UI strings
mcp__binary-ninja__binary_strings  # look for "Connect", "Start", "Acquisition"

# 5. Trace from string xrefs to write calls
mcp__binary-ninja__xref_data_refs_to <string_addr>
mcp__binary-ninja__function_callees <handler_addr>

# 6. Decompile the handler
mcp__binary-ninja__il_function <handler_addr> il_type="hlil"

# 7. Extract command bytes from the write buffer
mcp__binary-ninja__memory_read <buffer_addr> length=64

Radare2 Quick RE

mcp__radare2__open_file "/path/to/CGXAcquisition.exe"
mcp__radare2__analyze level=2
mcp__radare2__list_strings filter="Connect|Acquisition|Start|COM|Bluetooth"
mcp__radare2__list_imports filter="CreateFile|WriteFile|Bluetooth|WSA"
mcp__radare2__xrefs_to address=<import_addr>
mcp__radare2__decompile_function address=<caller>

Time-Unit Integration

The acquisition unlock determines which temporal scales are resolvable:

GF(3) Conservation

Related Skills

• reverse-engineering — General RE workflow, r2con speaker repos
• ghidra-mcp — Ghidra + radare2 MCP setup, port resurrection
• bci-colored-operad — BCI device pipeline, K⊣P adjunction
• cyton-dongle — OpenBCI Cyton connection (working reference)

References

• CGX Quick-20r Manual: manualslib.com/manual/2075541
• CGX Documents: cgxsystems.com/documents
• labstreaminglayer/App-Cognionics: github.com (deprecated C++ connector)
• mrphrazer/agentic-malware-analysis: synthesis.to/2026/03/18
• mrphrazer/binary-ninja-headless-mcp: 181 tools, headless
• sjkim1127/Reversecore_MCP: Ghidra + radare2 + YARA orchestration
• Ap3x/BinaryAnalysis-MCP: LIEF-based PE/ELF/Mach-O parsing