Shellcode test environment

a.c

#include <unistd.h>
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>


int main()
{
        char* buf= mmap(NULL, 1024,
            PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
        void (*f)(void) = buf;
        int fd = socket(AF_INET, SOCK_STREAM, 0);
        int result;
        struct addrinfo* sa = malloc(sizeof(struct addrinfo));
        sa->ai_family = AF_INET;
        sa->ai_flags = 0;
        sa->ai_socktype = SOCK_STREAM;
        sa->ai_protocol = 0;

        printf("getaddrinfo=%d\n", getaddrinfo("localhost", "31338",  NULL, &sa));

        sa->ai_addr->sa_family = AF_INET;

        result = connect(fd, sa->ai_addr, sa->ai_addrlen);
        if (result) {
            perror("connect");
            return 1;
        }
        read(fd, buf, 1024);
        f();
}

a.py

#!/usr/bin/env python

import socket

buf = open('buf', 'rb').read()
s = socket.socket()
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(('0.0.0.0', 31338))
while True:
    s.listen()
    s2, _ = s.accept()
    s2.send(buf)

buf.asm

bits 64
xor eax, eax
inc eax
mov ebx, 4
int 0x80

Dockerfile

FROM python:3.8
ADD a.c .
ADD a.py .
ADD buf.asm .
RUN apt-get update && apt-get install nasm && nasm buf.asm && make a
CMD /bin/bash -c 'python3 a.py & sleep 1; ./a ; echo "exit code=$?"'