daas setup

DownUnderCTF 2023/misc/daas/daas/Dockerfile

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+FROM aflplusplus/aflplusplus:latest
+
+ENV TMP_ENABLED=1
+
+RUN mkdir /root/chal
+COPY ./flag.txt /root/chal
+COPY ./daas.py /root/chal/pwn
+#RUN mv /root/chal/daas.py /root/chal/pwn
+
+RUN chmod +x /root/chal/pwn
+
+# decompyle3 only supports python <= 3.8
+RUN apt-get update \
+    && apt-get install -y libssl-dev openssl build-essential zlib1g-dev wget \
+	&& cd /tmp \
+	&& wget https://www.python.org/ftp/python/3.8.10/Python-3.8.10.tgz \
+	&& tar xzvf Python-3.8.10.tgz \
+	&& cd Python-3.8.10 \
+	&& ./configure \
+	&& make \
+	&& make install \
+	&& rm -rf /var/lib/apt/lists/*
+
+# 3.9.0 is latest version of decompyle3 as of writing this challenge
+RUN /usr/local/bin/python3.8 -m pip install decompyle3==3.9.0 
+#RUN mv /root/chal/flag.txt /home/ctf/chal/flag_$(tr -dc a-f0-9 < /dev/urandom | head -c32)

DownUnderCTF 2023/misc/daas/daas/daas.py

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+#!/usr/local/bin/python3.8
+
+import subprocess
+import sys
+import tempfile
+import base64
+
+print("Welcome to my .pyc decompiler as a service!")
+try:
+   pyc = base64.b64decode(input('Enter your pyc (base64):\n'))
+except:
+   print('There was an error with your base64 :(')
+   exit(1)
+
+with tempfile.NamedTemporaryFile(suffix='.pyc') as sandbox:
+    sandbox.write(pyc)
+    sandbox.flush()
+    pipes = subprocess.Popen(["/usr/local/bin/decompyle3", sandbox.name], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    stdout, stderr = pipes.communicate()
+    if pipes.returncode == 0 and len(stderr) == 0:
+        print(stdout.decode())
+    else:
+        print(stderr.decode())
+        print("There was an error in decompilation :(")

DownUnderCTF 2023/misc/daas/daas/flag.txt

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+DUCTF{...}