De1CTF 2019
Web
SSRF Me
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):
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):
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):
if (getSign(self.action, self.param) == self.sign):
return True
else:
return False #generate Sign For Action Scan.
@app.route("/geneSign", methods=['GET', 'POST'])
def geneSign():
param = urllib.unquote(request.args.get("param", "")) # ๅฐ param ็ๅๆฐ่งฃ็ ไธบๅๅง็ๅญ็ฌฆไธฒๅฝขๅผ๏ผ่ฅไธบ็ฉบๅไธบ็ฉบๅญ็ฌฆไธฒ
action = "scan"
return getSign(action, param)
@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())
@app.route('/')
def index():
return open("code.txt","r").read()
def scan(param):
socket.setdefaulttimeout(1)
try:
return urllib.urlopen(param).read()[:50] # ๅช่ฟๅURLๅ
ๅฎน็ๅ50ไธชๅญ็ฌฆ
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)ๅฏไปฅ่ทๅพไธไธช Hint flag is in ./flag.txt ๏ผ็ฎๆ ๅฐฑๆฏ่ฆ้่ฟไธ่ฟฐไปฃ็ ไธญ็ Task::Exec ๅฐ flag.txt ๅๅ
ฅ result.txt ๅ่ฏปๅ result.txt ่ทๅพ flag ใ็ฑไบๅคๆญ่ฏญๅฅๆฏ้่ฟ in ๅ
ณ้ฎๅญๆฅๅคๆญ็๏ผๅ ๆญคๅฆๆ self.action ไธญๆขๆ read ไนๆ scan ๅณๅฏๅๆถๆง่กใ
้ฆๅ
้่ฆ้่ฟ checkSign() ๏ผๅ
ๅฉ็จ getSign() ็ๆ Sign ๅฏไปฅๅพๅฐ md5(secert_key + param + action) ใ้่ฟๆ้ Payload ๅฆไธ
ๅณๅฏๅพๅฐ action ไธบ readscan ็ Sign ๏ผๅฆไธ
็ถๅๆ้ Payload ๅฆไธๆฅไฝฟๅพ flag.txt ๅๅ
ฅ result.txt ๅ่ฏปๅ result.txt ใ
ๅฐฑๅฏไปฅๅพๅฐ flag ไบ๏ผไนๅฏไปฅ้่ฟ MD5 ้ฟๅบฆๆๅฑๆปๅป่งฃๅณ่ฟ้้ข๏ผๅ
่ทๅ md5(secert_key + flag.txt + scan) ็ๅผ๏ผๆ้ Payload ๅฆไธ
ๅฏไปฅๅพๅฐๅๆพๅฆไธ
้่ฟ secert_key = os.urandom(16) ๅฏ็ฅ secert_key ้ฟ 16 ไฝ๏ผ้่ฟ hashpump ่ฟ่ก็ๆ Payload๏ผๅฆไธ
ๅฐฑๅฏไปฅๆฑๅบ md5(secert_key + flag.txt + scan + padding + read) ็ๅผ๏ผ้่ฟๆ้ Payload ๅฆไธ
ๅณๅฏๅพๅฐ flagใ
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