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- Generated screenshots for all 33 challenges (ESP, Hardware, IoT, OT, Misc, Web3) - Replaced all 123 placeholder lines with actual PNG image references - Cleaned duplicate images from previously partial updates - All write-ups now have full illustrated solutions
1.9 KiB
Executable File
1.9 KiB
Executable File
Let's All Love UART
| Field | Value |
|---|---|
| Category | IoT |
| Difficulty | Easy |
| Points | 500 |
| Author | Eun0us |
| CTF | Espilon 2026 |
Description
This challenge emulates a UART interface on a Lain router. Open both connections, interact as if it was real hardware.
- TX: Read only
- RX: Write only
Let's All Love Lain!
TL;DR
Open the TX and RX ports simultaneously. Send flag on the RX (write) port.
The flag is immediately printed on the TX (read) port.
Tools
| Tool | Purpose |
|---|---|
nc |
Split UART connection |
| Python 3 | Automated solver script |
Solution
Step 1 — Open both channels
# Terminal 1 — read device output
nc <host> 1111
# Terminal 2 — send commands
nc <host> 2222
Step 2 — Request the flag
In Terminal 2 (RX):
flag
Step 3 — Read the flag
In Terminal 1 (TX):
ESPILON{LAIN_TrUsT_U4RT}
Automated solver
#!/usr/bin/env python3
import socket
import threading
HOST = "<host>"
TX_PORT = 1111
RX_PORT = 2222
def reader():
with socket.create_connection((HOST, TX_PORT)) as s:
while True:
data = s.recv(4096)
if not data:
break
out = data.decode(errors="replace")
print(out, end="")
if "ESPILON{" in out:
break
tx_thread = threading.Thread(target=reader, daemon=True)
tx_thread.start()
with socket.create_connection((HOST, RX_PORT)) as s:
s.sendall(b"flag\n")
tx_thread.join()
Flag
ESPILON{LAIN_TrUsT_U4RT}