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.
Scoreboard frozen as of March 25, 2026.

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Challenge Index

#	Challenge	Category	Difficulty	Points
1	ESP Start	ESP	Easy	50
2	Jnouned Router	ESP	Multi	100/200/300/400
3	Phantom Byte	ESP	Multi	100/200/300/500
4	CAN Bus Implant	Hardware	Medium-Hard	500
5	Glitch The Wired	Hardware	Medium-Hard	500
6	NAVI I2C Sniff	Hardware	Medium-Hard	500
7	Phantom JTAG	Hardware	Medium-Hard	500
8	Serial Experimental 00	Hardware	Easy	150
9	Signal Tap Lain	Hardware	Medium-Hard	500
10	Wired SPI Exfil	Hardware	Medium-Hard	500
11	The Wired	Intro	Medium	400
12	Anesthesia Gateway	IoT	Medium-Hard	500
13	Cr4cK W1F1	IoT	Medium	—
14	Lain Br34kC0r3	IoT	Medium	500
15	Lain Br34kC0r3 V2	IoT	Hard	500
16	Lain VS Knights	IoT	Hard	—
17	Lets All Hate UART	IoT	Medium-Hard	500
18	Lets All Love UART	IoT	Easy	500
19	Nurse Call	IoT	Easy	200
20	Observe The Wired	IoT	Medium-Hard	—
21	Wired Airwave 013	IoT	Medium	500
22	Accela Signal	Misc	Hard	500
23	AETHER NET	Misc	Insane	—
24	Last Train 451	Misc	TBD	—
25	LAYER ZERO	Misc	Hard	600
26	Patient Portal	Misc	Medium-Hard	500
27	Cyberia Grid	OT	Medium-Hard	500
28	Operating Room	OT	Medium-Hard	500
29	Protocol Seven	OT	Hard	600
30	Schumann Resonance	OT	Medium	400
31	Tachibana SCADA	OT	Medium-Hard	500
32	GANTZ BALL CONTRACT	Web3	Insane	500
33	TACHIBANA FIRMWARE REGISTRY	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