update cdn

services/cdn/Dockerfile

@@ -0,0 +1,38 @@
+FROM python:3.12-slim
+
+ENV PYTHONDONTWRITEBYTECODE=1 \
+    PYTHONUNBUFFERED=1 \
+    PIP_NO_CACHE_DIR=1 \
+    DEBIAN_FRONTEND=noninteractive
+
+WORKDIR /app
+
+# System deps: exiftool + sshd + bash (sqlite CLI not required for Python sqlite3)
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends \
+      libimage-exiftool-perl \
+      openssh-server \
+      bash \
+ && rm -rf /var/lib/apt/lists/*
+
+# Unprivileged user for the app / SSH
+RUN useradd -m -d /home/ctfuser -s /bin/bash ctfuser
+
+# SSH minimal setup
+RUN mkdir -p /run/sshd && chmod 755 /run/sshd && ssh-keygen -A
+
+COPY chall/requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY /chall /app
+
+RUN chmod +x /app/entrypoint.sh && mkdir -p /app/uploads && chmod 755 /app/uploads
+
+RUN mkdir -p /data /app/uploads /run/sshd \
+    && chown -R ctfuser:ctfuser /app /app/uploads /data \
+    && chmod 755 /app
+
+EXPOSE 8000
+EXPOSE 22
+
+ENTRYPOINT ["/bin/bash", "/app/entrypoint.sh"]

services/cdn/README.md

@@ -0,0 +1,30 @@
+## CDN
+
+db used: sqlite
+flag.txt: GEMASTIK{random sha256 generated on app start}
+
+### feature:
+[authentication required with login and register, register default as "user" role]
+1. upload image
+
+### Vulns
+#### vuln1: SSTI on image Date Created metadata, exiftool cant insert this, need to write the image's blob
+example: 
+```bash
+(base) jons@01-20-jonathanmarbun:/mnt/c/1Jonathan/CTFS/gawe/gms25/web2/exploit$ exiftool -overwrite_original -IPTC:DateCreated="{{7*7}}" image.png
+Warning: Invalid date format (use YYYY:mm:dd) in IPTC:DateCreated (ValueConvInv)
+Nothing to do.
+```
+payload to inject:
+```{{lipsum.__builtins__['open']('flag.txt').read()}}```
+
+when editing the Date Created metadata manually, somehow it has limit of 46 char (but we can expand that to make it more by deleting the content of another metadata) -> check ssti.png
+it probably have different behavior on another image file or format
+payload: check exploit/exp3.py
+
+#### vuln2: 
+
+### Patching Rule?
+- dont remove flag.txt/changes its content
+- ensure image metadata generation still available
+- ensure exiftool still used

services/cdn/chall/app.py

@@ -13,7 +13,7 @@ from werkzeug.utils import secure_filename
 APP_DIR = os.path.dirname(os.path.abspath(__file__))
 DB_PATH = os.path.join(APP_DIR, "data.db")
 UPLOAD_DIR = os.path.join(APP_DIR, "uploads")
-FLAG_PATH = os.path.join(APP_DIR, "flag.txt")
+FLAG_PATH = os.path.join("/flag.txt")
 
 ALLOWED_EXT = {"png", "jpg", "jpeg", "bmp"}
 MAX_CONTENT_LENGTH = 8 * 1024 * 1024
@@ -261,5 +261,4 @@ def too_large(_):
 if __name__ == "__main__":
     with app.app_context():
         init_db()
-        generate_flag_at_boot()
     app.run(host="0.0.0.0", port=8000, debug=False)

services/cdn/chall/entrypoint.sh

@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+umask 002  # group-writable (helps with bind mounts)
+
+APP_DIR="/app"
+UPLOADS_DIR="${APP_DIR}/uploads"
+DATA_DIR="/data"
+DBFILE="${DATA_DIR}/app.db"
+FLAG_FILE="/flag.txt"
+
+mkdir -p "${UPLOADS_DIR}" "${DATA_DIR}"
+
+# Make sure runtime dirs are writable (bind-mounts may ignore chown; that's OK)
+chown -R ctfuser:ctfuser "${UPLOADS_DIR}" "${DATA_DIR}" 2>/dev/null || true
+chmod 775 "${UPLOADS_DIR}" "${DATA_DIR}" || true
+
+# ------- Start SSH (and set password if provided) -------
+if [[ -n "${SSH_PASSWORD:-}" ]]; then
+  echo "ctfuser:${SSH_PASSWORD}" | chpasswd || true
+fi
+
+if command -v service >/dev/null 2>&1; then
+  service ssh start || /usr/sbin/sshd &
+else
+  /usr/sbin/sshd &
+fi
+# -------------------------------------------------------
+
+# Initialize DB AS ctfuser (so SQLite can write WAL/SHM next to it)
+su -s /bin/bash -c "python - <<'PY'
+import app as m
+from contextlib import contextmanager
+
+@contextmanager
+def ctx():
+    with m.app.app_context():
+        yield
+
+with ctx():
+    # your function should create tables if missing
+    m.init_db()
+    # OPTIONAL: if you had a generate_flag_at_boot, call it here as well
+    try:
+        m.generate_flag_at_boot()
+    except Exception:
+        pass
+print('DB initialized by ctfuser.')
+PY
+" ctfuser
+
+# OPTIONAL: if your filesystem dislikes WAL, uncomment:
+# su -s /bin/bash -c \"python - <<'PY'
+# import sqlite3
+# import os
+# db = sqlite3.connect(os.environ.get('DB_PATH', '${DBFILE}'))
+# db.execute('PRAGMA journal_mode=DELETE;')
+# db.execute('PRAGMA synchronous=NORMAL;')
+# db.close()
+# print('SQLite journal_mode=DELETE applied.')
+# PY
+# \" ctfuser
+
+# Secure the flag file if present
+if [ -d "${FLAG_FILE}" ]; then
+  if [ -f "${FLAG_FILE}" ]; then
+    chown root:root "${FLAG_FILE}" || true
+    chmod 444 "${FLAG_FILE}" || true
+  fi
+else
+  if [ -f "${FLAG_FILE}" ]; then
+    chown root:root "${FLAG_FILE}" || true
+    chmod 444 "${FLAG_FILE}" || true
+  fi
+fi
+
+echo "Starting Flask app on 0.0.0.0:8000 as ctfuser…"
+exec su -s /bin/bash -c "cd '${APP_DIR}' && python app.py" ctfuser

services/cdn/docker-compose.yml

@@ -0,0 +1,15 @@
+version: "3.8"
+services:
+  cdn_services:
+    container_name: cdn_container
+    hostname: cdn
+    build: .
+    ports:
+      - "4500:8000"  # app
+      - "4522:22"    # ssh
+    environment:
+      SECRET_KEY: "c75f1259a4c95bb31563405d488d7bf9c0eaf4d562fd13557624f8e18eb5cfff"
+      # Optional: set SSH password for ctfuser at runtime
+      SSH_PASSWORD: "root"
+      # Optional: override if your app reads it
+    restart: always

services/cdn/exploit/exp1.py

@@ -7,7 +7,7 @@ import requests
 
 print("SSTI (Vuln) Exploit — fixed HOST env, redirects, timeouts")
 
-HOST = "http://localhost:4414"
+HOST = "http://localhost:4500"
 REGISTER_URL = f"{HOST}/register"
 LOGIN_URL    = f"{HOST}/login"
 UPLOAD_URL   = f"{HOST}/upload"

services/cdn/src/Dockerfile

@@ -1,21 +0,0 @@
-FROM python:3.12-slim
-
-ENV PYTHONDONTWRITEBYTECODE=1 \
-    PYTHONUNBUFFERED=1 \
-    PIP_NO_CACHE_DIR=1
-
-WORKDIR /app
-
-RUN apt-get update \
- && apt-get install -y --no-install-recommends libimage-exiftool-perl \
- && rm -rf /var/lib/apt/lists/*
-
-COPY requirements.txt .
-RUN pip install -r requirements.txt
-
-COPY . /app
-RUN chmod +x /app/entrypoint.sh \
- && mkdir -p /app/uploads && chmod 755 /app/uploads
-
-EXPOSE 8000
-ENTRYPOINT ["/bin/bash", "entrypoint.sh"]

services/cdn/src/docker-compose.yml

@@ -1,13 +0,0 @@
-version: "3.8"
-services:
-  cdn:
-    build: .
-    container_name: cdn_container
-    ports:
-      - "11000:8000"
-    environment:
-      SECRET_KEY: "c75f1259a4c95bb31563405d488d7bf9c0eaf4d562fd13557624f8e18eb5cfff"
-      RESEED_FLAG: "1"
-    volumes:
-      - ./uploads:/app/uploads
-    restart: unless-stopped

services/cdn/src/entrypoint.sh

@@ -1,30 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-mkdir -p /app/uploads
-chmod 755 /app/uploads
-
-python - <<'PY'
-import os
-import app as m
-with m.app.app_context():
-    m.init_db()
-    m.generate_flag_at_boot()
-print("DB & flag initialized.")
-PY
-
-FLAG_PATH="${FLAG_PATH:-/app/flag.txt}"
-
-if [ -d "$FLAG_PATH" ]; then
-  if [ -f "$FLAG_PATH/flag.txt" ]; then
-    chown root:root "$FLAG_PATH/flag.txt" || true
-    chmod 444 "$FLAG_PATH/flag.txt" || true
-  fi
-else
-  if [ -f "$FLAG_PATH" ]; then
-    chown root:root "$FLAG_PATH" || true
-    chmod 444 "$FLAG_PATH" || true
-  fi
-fi
-
-exec python app.py

services/cdn/src/flag_seed.py

@@ -1,7 +0,0 @@
-# Convenience: reseed flag once without starting server
-import hashlib, secrets, os
-FLAG_PATH = os.path.join(os.path.dirname(__file__), "flag.txt")
-sha = hashlib.sha256(secrets.token_bytes(32)).hexdigest()
-with open(FLAG_PATH, "w", encoding="utf-8") as fh:
-    fh.write(f"GEMASTIK{{{sha}}}\n")
-print("Flag reseeded:", open(FLAG_PATH).read().strip())