# ESPILON CTF 2026 — Official Write-ups

Official write-ups for **ESPILON CTF 2026**, a hardware/IoT/OT themed CTF
set in the *Serial Experiments Lain* universe.

> Challenges remain accessible at [ctf.espilon.net](https://ctf.espilon.net).  
> Scoreboard frozen as of March 25, 2026.

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## Challenge Index

| # | Challenge | Category | Difficulty | Points |
|---|-----------|----------|-----------|--------|
| 1 | [ESP Start](ESP/ESP_Start/README.md) | ESP | Easy | 50 |
| 2 | [Jnouned Router](ESP/Jnouner_Router/README.md) | ESP | Multi | 100/200/300/400 |
| 3 | [Phantom Byte](ESP/Phantom_Byte/README.md) | ESP | Multi | 100/200/300/500 |
| 4 | [CAN Bus Implant](Hardware/CAN_Bus_Implant/README.md) | Hardware | Medium-Hard | 500 |
| 5 | [Glitch The Wired](Hardware/Glitch_The_Wired/README.md) | Hardware | Medium-Hard | 500 |
| 6 | [NAVI I2C Sniff](Hardware/NAVI_I2C_Sniff/README.md) | Hardware | Medium-Hard | 500 |
| 7 | [Phantom JTAG](Hardware/Phantom_JTAG/README.md) | Hardware | Medium-Hard | 500 |
| 8 | [Serial Experimental 00](Hardware/Serial_Experimental_00/README.md) | Hardware | Easy | 150 |
| 9 | [Signal Tap Lain](Hardware/Signal_Tap_Lain/README.md) | Hardware | Medium-Hard | 500 |
| 10 | [Wired SPI Exfil](Hardware/Wired_SPI_Exfil/README.md) | Hardware | Medium-Hard | 500 |
| 11 | [The Wired](Intro/The_Wired/README.md) | Intro | Medium | 400 |
| 12 | [Anesthesia Gateway](IoT/Anesthesia_Gateway/README.md) | IoT | Medium-Hard | 500 |
| 13 | [Cr4cK W1F1](IoT/Cr4cK_w1f1/README.md) | IoT | Medium | — |
| 14 | [Lain Br34kC0r3](IoT/Lain_Br34kC0r3/README.md) | IoT | Medium | 500 |
| 15 | [Lain Br34kC0r3 V2](IoT/Lain_Br34kC0r3_V2/README.md) | IoT | Hard | 500 |
| 16 | [Lain VS Knights](IoT/Lain_VS_Knights/README.md) | IoT | Hard | — |
| 17 | [Lets All Hate UART](IoT/Lets_All_Hate_UART/README.md) | IoT | Medium-Hard | 500 |
| 18 | [Lets All Love UART](IoT/Lets_All_Love_UART/README.md) | IoT | Easy | 500 |
| 19 | [Nurse Call](IoT/Nurse_Call/README.md) | IoT | Easy | 200 |
| 20 | [Observe The Wired](IoT/Observe_The_Wired/README.md) | IoT | Medium-Hard | — |
| 21 | [Wired Airwave 013](IoT/Wired_Airwave_013/README.md) | IoT | Medium | 500 |
| 22 | [Accela Signal](Misc/Accela_Signal/README.md) | Misc | Hard | 500 |
| 23 | [AETHER NET](Misc/AETHER_NET/README.md) | Misc | Insane | — |
| 24 | [Last Train 451](Misc/Last_Train_451/README.md) | Misc | TBD | — |
| 25 | [LAYER ZERO](Misc/LAYER_ZERO/README.md) | Misc | Hard | 600 |
| 26 | [Patient Portal](Misc/Patient_Portal/README.md) | Misc | Medium-Hard | 500 |
| 27 | [Cyberia Grid](OT/Cyberia_Grid/README.md) | OT | Medium-Hard | 500 |
| 28 | [Operating Room](OT/Operating_Room/README.md) | OT | Medium-Hard | 500 |
| 29 | [Protocol Seven](OT/Protocol_Seven/README.md) | OT | Hard | 600 |
| 30 | [Schumann Resonance](OT/Schumann_Resonance/README.md) | OT | Medium | 400 |
| 31 | [Tachibana SCADA](OT/Tachibana_SCADA/README.md) | OT | Medium-Hard | 500 |
| 32 | [GANTZ BALL CONTRACT](Web3/GANTZ_BALL_CONTRACT/README.md) | Web3 | Insane | 500 |
| 33 | [TACHIBANA FIRMWARE REGISTRY](Web3/TACHIBANA_FIRMWARE_REGISTRY/README.md) | Web3 | Insane | 500 |

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## Categories

| Category | Description |
|----------|-------------|
| **ESP** | ESP32 firmware — flashing, UART, WiFi, custom protocols |
| **Hardware** | Bus interfaces — UART, I2C, SPI, JTAG, CAN, signal decoding, voltage glitching |
| **Intro** | Entry point — ESPILON bot C2 infrastructure |
| **IoT** | IoT protocols — MQTT, CoAP, UART, SDR/FSK, WiFi cracking |
| **Misc** | Mixed — signal processing, web exploitation, multi-pivot |
| **OT** | Industrial protocols — Modbus, BACnet, OPC-UA, EtherNet/IP |
| **Web3** | Ethereum — reentrancy, assembly underflow, bytecode reversal |

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*Author: Eun0us — ESPILON CTF 2026*