SSRF Me

源码

#! /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) # 随机生成16位随机数

class Task:
    def __init__(self, action, param, sign, ip): # task对象的__init__方法，其中根据传入的ip的md5生成沙盒
        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): # task对象的Exec方法，分别对sign以及action进行判断，分别执行scan以及read操作
        result = {}
        result['code'] = 500
        if (self.checkSign()):
            if "scan" in self.action:
                tmpfile = open("./%s/result.txt" % self.sandbox, 'w')
                resp = scan(self.param)
                if (resp == "Connection Timeout"):
                    result['data'] = resp
                else:
                    print resp
                    tmpfile.write(resp)
                    tmpfile.close()
                result['code'] = 200
            if "read" in self.action:
                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): # 检查签名是否正确
        if (getSign(self.action, self.param) == self.sign):
            return True
        else:
            return False

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

@app.route('/De1ta',methods=['GET','POST']) # 路由/De1ta 执行函数exec
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('/') # 源码
def index(): 
    return open("code.txt","r").read()

def scan(param):
    socket.setdefaulttimeout(1)
    try:
        return urllib.urlopen(param).read()[:50]
    except:
        return "Connection Timeout"

def getSign(action, param):
    return hashlib.md5(secert_key + param + action).hexdigest()

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

def waf(param):
    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',port=80)

分析代码逻辑大致如下

# 沿着路由走的话
# 路由 ('/') 获得网站源码
@app.route('/') 
def index(): 
    return open("code.txt","r").read()

# 路由 ('/geneSign') GET方式获得param，action默认为"scan"，传入getSign
@app.route("/geneSign", methods=['GET', 'POST'])
def geneSign():
    param = urllib.unquote(request.args.get("param", ""))
    action = "scan"
    return getSign(action, param)

# 函数 getSign(action, param) 返回md5(secert_key + param + action)
def getSign(action, param):
    return hashlib.md5(secert_key + param + action).hexdigest()

# 路由 ('/De1ta')  通过cooies传入action以及sign，通过get传入param，获得ip
@app.route('/De1ta',methods=['GET','POST']) 
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())
# 函数 waf(param) 如果存在gopher伪协议或file伪协议
def waf(param): 
    check=param.strip().lower()
    if check.startswith("gopher") or check.startswith("file"):
        return True
    else:
        return False
# 最后执行exec

再看看关键的检验签名函数

# 函数 getSign(action, param) 返回md5(secert_key + param + action)
def getSign(action, param):
    return hashlib.md5(secert_key + param + action).hexdigest()

首先我们先生成签名

/geneSign?param=flag.txtread

由于最后我们要调用的是read函数读flag.txt，但是在生成签名时的action参数为"scan"，所以我们要传入"read"，这样生成的签名就包括了"scan"以及"read"。