De1CTF 2019-WEB-SSRF Me

复现地址：https://buuoj.cn/challenges#[De1CTF%202019]SSRF%20Me

#! /usr/bin/env python
#encoding=utf-8
from flask import Flask
from flask import request
import socket
import hashlib
import urllib
import sys
import os
import json
reload(sys)
sys.setdefaultencoding('latin1')

app = Flask(__name__)

secert_key = os.urandom(16)


class Task:
    def __init__(self, action, param, sign, ip):#python得构造方法
        self.action = action
        self.param = param
        self.sign = sign
        self.sandbox = md5(ip)
        if(not os.path.exists(self.sandbox)):          #SandBox For Remote_Addr
            os.mkdir(self.sandbox)

    def Exec(self):#定义的命令执行函数，此处调用了scan这个自定义的函数
        result = {}
        result['code'] = 500
        if (self.checkSign()):
            if "scan" in self.action:#action要写scan
                tmpfile = open("./%s/result.txt" % self.sandbox, 'w')
                resp = scan(self.param) # 此处是文件读取得注入点
                if (resp == "Connection Timeout"):
                    result['data'] = resp
                else:
                    print resp #输出结果
                    tmpfile.write(resp)
                    tmpfile.close()
                result['code'] = 200
            if "read" in self.action:#action要加read
                f = open("./%s/result.txt" % self.sandbox, 'r')
                result['code'] = 200
                result['data'] = f.read()
            if result['code'] == 500:
                result['data'] = "Action Error"
        else:
            result['code'] = 500
            result['msg'] = "Sign Error"
        return result

    def checkSign(self):
        if (getSign(self.action, self.param) == self.sign): #!!!校验
            return True
        else:
            return False


#generate Sign For Action Scan.
@app.route("/geneSign", methods=['GET', 'POST']) # !!!这个路由用于测试
def geneSign():
    param = urllib.unquote(request.args.get("param", "")) 
    action = "scan"
    return getSign(action, param)


@app.route('/De1ta',methods=['GET','POST'])#这个路由是我萌得最终注入点
def challenge():
    action = urllib.unquote(request.cookies.get("action"))
    param = urllib.unquote(request.args.get("param", ""))
    sign = urllib.unquote(request.cookies.get("sign"))
    ip = request.remote_addr
    if(waf(param)):
        return "No Hacker!!!!"
    task = Task(action, param, sign, ip)
    return json.dumps(task.Exec())

@app.route('/')#根目录路由，就是显示源代码得地方
def index():
    return open("code.txt","r").read()


def scan(param):#这是用来扫目录得函数
    socket.setdefaulttimeout(1)
    try:
        return urllib.urlopen(param).read()[:50]
    except:
        return "Connection Timeout"

def getSign(action, param):#!!!这个应该是本题关键点,此处注意顺序先是param后是action
    return hashlib.md5(secert_key + param + action).hexdigest()


def md5(content):
    return hashlib.md5(content).hexdigest()


def waf(param):#这个waf比较没用好像
    check=param.strip().lower()
    if check.startswith("gopher") or check.startswith("file"):
        return True
    else:
        return False

    
if __name__ == '__main__':
    app.debug = False
    app.run(host='0.0.0.0')

先解释部分函数:

参照这个吧
https://xz.aliyun.com/t/5927