The Catch 2025

Reactor startup (1)

Zadání

Hi, trainee,

normally, this task would be assigned to a senior worker, but none are available now, so your mission will be to start the shut-down reactor at the Granite Peak Nuclear as quickly as possible — by following the startup checklist and entering the sequence step by step. However, we have a big problem: the standard items (e.g., “primary circuit leak test”) have somehow been renamed to nonsense by some cat-holic. Only the first item, Initiate Control Circuits, and the last one, Phase the Power Plant, remain unchanged.

The radiation situation at Granite Peak Nuclear remains normal.

Stay grounded!

Interface for starting sequence is at http://gpn.powergrid.tcc/

Nápovědy (Hints)

1. All services in powergrid.tcc domain are accessible via VPN only.

2. Don’t worry, the reactor has built-in safeguards, so in case of an incorrect sequence it will automatically shut down again.

3. Some simple automation with a script would be quite handy (doing it manually is feasible, but would be a gargantuan task).

Řešení

Na webové stránce ze zadání je možné zadávat povely reaktoru. První je Initiate Control Circuits. Pokud se zadá Phase the Power Plant, vypíše se povel, který byl očekáván. Podle nápovědy bude tedy nejlepší řešit úlohu skriptem, ve kterém budeme postupně přidávat příkazy.

import requests
import re

s = requests.Session()

commands = ["Initiate Control Circuits"]
lastCommand = "Phase the Power Plant"

while True:
    for command in commands:
        r = s.post("http://gpn.powergrid.tcc/", data={"command": command})

    r = s.post("http://gpn.powergrid.tcc/", data={"command": lastCommand})

    if "Invalid sequence. Item" in r.text:
        missingCommand = r.text.split("'")
        print(missingCommand[1])
        commands.append(missingCommand[1])
    else:
        print(re.search(r".*(FLAG{.*}).*", r.text).group(1))
        break

Flag

FLAG{WuYg-ynFt-US0N-ZYv9}