Add files via upload

services/sheesh/Dockerfile

@@ -0,0 +1,32 @@
+FROM python:3.12-slim
+
+ARG PASSWORD=root
+ENV DEBIAN_FRONTEND=noninteractive
+ENV HOME=/home/ctf
+WORKDIR /home/ctf/chall
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    openssh-server \
+    build-essential \
+    libffi-dev \
+    libssl-dev \
+    python3-dev \
+    bash \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN useradd -m -d /home/ctf -s /bin/bash ctf && \
+    echo "ctf:${PASSWORD}" | chpasswd
+
+RUN mkdir -p /var/run/sshd
+
+COPY requirements.txt /tmp/requirements.txt
+RUN pip install --no-cache-dir -r /tmp/requirements.txt
+
+COPY ./src /home/ctf/chall/src
+COPY ./start.sh /start.sh
+RUN chmod +x /start.sh /home/ctf/chall/src/run.sh
+
+RUN chown -R root:root /home/ctf/chall && chmod -R 555 /home/ctf/chall
+
+EXPOSE 8000 22
+CMD ["/start.sh"]

services/sheesh/chall.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+
+import os
+import binascii
+import hashlib
+from Crypto.Cipher import AES
+from Crypto.Util.Padding import pad, unpad
+
+seed_bits = 23              
+seed_max  = 1 << seed_bits
+seed_len  = (seed_bits + 7) // 8   
+key = os.urandom(16)   
+
+def hash(seed_int: int) -> bytes:
+    sb = seed_int.to_bytes(seed_len, "big")
+    return hashlib.sha256(sb).digest()[:16]
+
+seed = int.from_bytes(os.urandom(4), "big") % seed_max
+seed2 = int.from_bytes(os.urandom(4), "big") % seed_max
+K1 = hash(seed)
+K2 = hash(seed2)
+
+with open("/flag.txt","rb") as f:
+    FLAG = f.read()
+
+def read(prompt: str):
+    s = input(prompt).strip()
+    try:
+        return binascii.unhexlify(s)
+    except Exception:
+        print("hmm")
+        return None
+
+def enc_cfb(pt: bytes) -> bytes:
+    iv = os.urandom(16)
+    aes = AES.new(key, AES.MODE_CFB, iv=iv, segment_size=128)
+    pt2 = pt + FLAG[:len(FLAG)//2]
+    ct = aes.encrypt(pt2)
+    return iv + ct
+
+def enc_cbc(data: bytes, iv1: bytes, iv2: bytes, padd: bool) -> bytes:
+    x  = pad(data, 16) if padd else data
+    c1 = AES.new(K1, AES.MODE_CBC, iv=iv1).encrypt(x)     
+    c2 = AES.new(K2, AES.MODE_CBC, iv=iv2).encrypt(c1)     
+    return c2
+
+def menu():
+    print("""
+1. encrypt 
+2. profit 
+3. get third 
+4. exit
+    """)
+
+third = 0
+while True:
+    menu()
+    op = input("> ").strip()
+
+    if op == "1":
+        data = read("pt: ")
+        if data is None:
+            print()
+            continue
+        out = enc_cfb(data)
+        print("ct: ", out.hex())
+        print()
+
+    elif op == "2":
+        iv1 = os.urandom(16)
+        iv2 = os.urandom(16)
+        ct  = enc_cbc(FLAG, iv1, iv2, padd=True)
+        print("iv1: ", iv1.hex())
+        print("iv2: ", iv2.hex())
+        print("ct: ", ct.hex())
+        print()
+
+    elif op == "3":
+        if third:
+            print("sheesh")
+            continue
+        block = read("pt: ")
+        if block is None:
+            print()
+            continue
+        if len(block) != 16:
+            print("hmmm\n")
+            continue
+        iv1 = os.urandom(16)
+        iv2 = os.urandom(16)
+        ct  = enc_cbc(block, iv1, iv2, padd=0)  
+        print("iv1: ", iv1.hex())
+        print("iv2: ", iv2.hex())
+        print("ct: ", ct.hex())
+        third = 1
+        print()
+
+    elif op == "4":
+        break
+    else:
+        print("mabokkkk?")

services/sheesh/dist/chall.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+
+import os
+import binascii
+import hashlib
+from Crypto.Cipher import AES
+from Crypto.Util.Padding import pad, unpad
+
+seed_bits = 23              
+seed_max  = 1 << seed_bits
+seed_len  = (seed_bits + 7) // 8   
+key = os.urandom(16)   
+
+def hash(seed_int: int) -> bytes:
+    sb = seed_int.to_bytes(seed_len, "big")
+    return hashlib.sha256(sb).digest()[:16]
+
+seed = int.from_bytes(os.urandom(4), "big") % seed_max
+seed2 = int.from_bytes(os.urandom(4), "big") % seed_max
+K1 = hash(seed)
+K2 = hash(seed2)
+
+with open("/flag.txt","rb") as f:
+    FLAG = f.read()
+
+def read(prompt: str):
+    s = input(prompt).strip()
+    try:
+        return binascii.unhexlify(s)
+    except Exception:
+        print("hmm")
+        return None
+
+def enc_cfb(pt: bytes) -> bytes:
+    iv = os.urandom(16)
+    aes = AES.new(key, AES.MODE_CFB, iv=iv, segment_size=128)
+    pt2 = pt + FLAG[:len(FLAG)//2]
+    ct = aes.encrypt(pt2)
+    return iv + ct
+
+def enc_cbc(data: bytes, iv1: bytes, iv2: bytes, padd: bool) -> bytes:
+    x  = pad(data, 16) if padd else data
+    c1 = AES.new(K1, AES.MODE_CBC, iv=iv1).encrypt(x)     
+    c2 = AES.new(K2, AES.MODE_CBC, iv=iv2).encrypt(c1)     
+    return c2
+
+def menu():
+    print("""
+1. encrypt 
+2. profit 
+3. get third 
+4. exit
+    """)
+
+third = 0
+while True:
+    menu()
+    op = input("> ").strip()
+
+    if op == "1":
+        data = read("pt: ")
+        if data is None:
+            print()
+            continue
+        out = enc_cfb(data)
+        print("ct: ", out.hex())
+        print()
+
+    elif op == "2":
+        iv1 = os.urandom(16)
+        iv2 = os.urandom(16)
+        ct  = enc_cbc(FLAG, iv1, iv2, padd=True)
+        print("iv1: ", iv1.hex())
+        print("iv2: ", iv2.hex())
+        print("ct: ", ct.hex())
+        print()
+
+    elif op == "3":
+        if third:
+            print("sheesh")
+            continue
+        block = read("pt: ")
+        if block is None:
+            print()
+            continue
+        if len(block) != 16:
+            print("hmmm\n")
+            continue
+        iv1 = os.urandom(16)
+        iv2 = os.urandom(16)
+        ct  = enc_cbc(block, iv1, iv2, padd=0)  
+        print("iv1: ", iv1.hex())
+        print("iv2: ", iv2.hex())
+        print("ct: ", ct.hex())
+        third = 1
+        print()
+
+    elif op == "4":
+        break
+    else:
+        print("mabokkkk?")

services/sheesh/docker-compose.yml

@@ -0,0 +1,16 @@
+version: "3.8"
+
+services:
+  sheesh:
+    container_name: sheesh_container
+    hostname: sheesh
+    restart: always
+    build:
+      context: .
+      args:
+          - PASSWORD=root
+    ports:
+      - "12000:8000"
+      - "12022:22"
+    environment:
+      - FLAG=GEMASTIK{local_flag}

services/sheesh/requirements.txt

@@ -0,0 +1 @@
+pycryptodome

services/sheesh/run.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+exec socat tcp-l:8000,reuseaddr,fork exec:"python3 ./chall.py"

services/sheesh/start.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+set -e
+
+ssh-keygen -A
+
+grep -q "^PermitRootLogin" /etc/ssh/sshd_config && \
+  sed -i "s/^PermitRootLogin.*/PermitRootLogin no/" /etc/ssh/sshd_config || \
+  echo "PermitRootLogin no" >> /etc/ssh/sshd_config
+
+grep -q "^PasswordAuthentication" /etc/ssh/sshd_config && \
+  sed -i "s/^PasswordAuthentication.*/PasswordAuthentication yes/" /etc/ssh/sshd_config || \
+  echo "PasswordAuthentication yes" >> /etc/ssh/sshd_config
+
+echo "AllowUsers ctf" >> /etc/ssh/sshd_config
+
+/usr/sbin/sshd
+
+if [ -n "$FLAG" ]; then
+    echo "$FLAG" > /flag.txt
+    chmod 644 /flag.txt
+    chown root:root /flag.txt
+fi
+
+exec su -c "cd /home/ctf/chall/src && ./run.sh" -s /bin/bash ctf