Initial commit

services.old/back-to-basic/Dockerfile

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+FROM public.ecr.aws/docker/library/ubuntu:20.04
+
+ARG PASSWORD
+
+ENV DEBIAN_FRONTEND noninteractive
+
+RUN echo root:${PASSWORD} | chpasswd
+RUN apt-get update && apt-get install -y openssh-server lib32z1 xinetd cmake gcc curl
+RUN echo "PasswordAuthentication yes" >> /etc/ssh/sshd_config
+RUN echo "PermitRootLogin yes" >> /etc/ssh/sshd_config
+RUN service ssh start
+
+RUN useradd -m ctf
+
+WORKDIR /ctf
+
+RUN echo "Connection blocked" > /etc/banner_fail
+COPY ctf.xinetd /etc/xinetd.d/ctf
+COPY ./src/main.c ./
+COPY ./start.sh ./
+RUN gcc /ctf/main.c -no-pie -fno-stack-protector -Wl,-z,relro,-z,now -o /ctf/main
+RUN touch /flag.txt
+RUN chmod -R 755 /ctf
+RUN chmod +x /ctf/start.sh
+
+ENTRYPOINT []
+CMD ["/usr/sbin/xinetd", "-dontfork"]
+
+EXPOSE 8000

services.old/back-to-basic/ctf.xinetd

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+service ctf
+{
+    disable = no
+    socket_type = stream
+    protocol    = tcp
+    wait        = no
+    user        = root
+    type        = UNLISTED
+    port        = 8000
+    bind        = 0.0.0.0
+    server      = /bin/sh
+    server_args = /ctf/start.sh
+    banner_fail = /etc/banner_fail
+    # safety options
+    per_source  = 10 # the maximum instances of this service per source IP address
+    rlimit_cpu  = 1 # the maximum number of CPU seconds that the service may use
+    #rlimit_as  = 1024M # the Address Space resource limit for the service
+}

services.old/back-to-basic/src/main.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+void give_me_idea() {
+  char buf[64];
+  puts("Do you have a good idea?");
+  fgets(buf, 200, stdin);
+}
+
+void main() {
+  setbuf(stdout, NULL);
+  give_me_idea();
+  puts("hmm... I'm also think the same thing...");
+  return 0;
+}

services.old/back-to-basic/start.sh

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+#!/bin/sh
+/usr/sbin/sshd -D &
+su ctf -c "/ctf/main"