Misc1——We1come

https://t.me/De1CTF ，需要加Telegram群，需要VPN,群里有发签到的flag

Misc2——Mine Sweeping

下载下来是一个扫雷游戏

在没有雷的地方组成的其实是一个二维码，因为踩雷后不会重置雷的位置，所以爆破每一个点是否有雷就可以了。表示此生不再想玩扫雷了。

最后得到了大概是这样的布局

写个脚本画出来

from PIL import Image
import random
str2=[]
with open('p.txt', 'r') as f:str2=f.readlines()
str1=[]
for i in str2:str1.append(i)str1.append(i)str1.append(i)str1.append(i)str1.append(i)str1.append(i)print(len(str1[0]))
print(len(str1))
c = Image.new("RGB",(len(str1[0]),len(str1)))
for j in range (0,len(str1)):for i in range (0,len(str1[0])-1):a=str1[j]if a[i]=="1":c.putpixel([i,j],(255,255,255))else :c.putpixel([i,j],(0,0,0))c = c.resize((200, 200),Image.ANTIALIAS)
c.show()
c.save("c.png")

最后扫码得到网址，访问即可得到flag

Web1——SSRF Me

SSRF(Server-Side Request Forgery:服务器端请求伪造) 是一种由攻击者构造形成由服务端发起请求的一个安全漏洞。一般情况下，SSRF是要目标网站的内部系统。（因为他是从内部系统访问的，所有可以通过它攻击外网无法访问的内部系统，也就是把目标网站当中间人）

源码如下

#! /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):self.action = actionself.param = paramself.sign = signself.sandbox = md5(ip)if(not os.path.exists(self.sandbox)):          #SandBox For Remote_Addros.mkdir(self.sandbox)def Exec(self):result = {}result['code'] = 500if (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'] = respelse:print resptmpfile.write(resp)tmpfile.close()result['code'] = 200if "read" in self.action:f = open("./%s/result.txt" % self.sandbox, 'r')result['code'] = 200result['data'] = f.read()if result['code'] == 500:result['data'] = "Action Error"else:result['code'] = 500result['msg'] = "Sign Error"return resultdef checkSign(self):if (getSign(self.action, self.param) == self.sign):return Trueelse:return False#generate Sign For Action Scan.
@app.route("/geneSign", methods=['GET', 'POST'])
def geneSign():param = urllib.unquote(request.args.get("param", ""))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_addrif(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]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 Trueelse:return Falseif __name__ == '__main__':app.debug = Falseapp.run(host='0.0.0.0',port=80)

说实话题目不是很难，就是代码有点长，要好好分析下代码逻辑。

首先可以知道，这段代码的主要的一个入口是在这里

@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_addrif(waf(param)):return "No Hacker!!!!"task = Task(action, param, sign, ip)return json.dumps(task.Exec())

通过访问/De1ta，会去获取cookie中的action和sign两个参数，同时还会获得一个url传参param。然后会去初始化一个Task对象，并且执行Task对象的Exec方法

然后执行Exec方法就看到调用了checkSign这个方法

 def checkSign(self):if (getSign(self.action, self.param) == self.sign):return Trueelse:return False

他会去将我们传入的sign和getSign(self.action, self.param)比较，相等才能执行后面的关键代码

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

这个sign我们还有一个入口是可以获取的

@app.route("/geneSign", methods=['GET', 'POST'])
def geneSign():param = urllib.unquote(request.args.get("param", ""))action = "scan"return getSign(action, param)

所以其实我们只要之后传入的param和这个/geneSign传入的param一样，然后action也等于scan，然后拿这边返回给我们的sign是肯定可以通过checkSign的

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'] = respelse:print resptmpfile.write(resp)tmpfile.close()result['code'] = 200if "read" in self.action:f = open("./%s/result.txt" % self.sandbox, 'r')result['code'] = 200result['data'] = f.read()if result['code'] == 500:result['data'] = "Action Error"

但是我们现在是要令scan和read都是action内容的一部分，才可以成功读到那边写入的数据。

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

scan()这个方法就是访问param这个地址，将内容的前50读取出来
所以我们可以利用这个来读服务器内部的flag.txt文件

现在就是要令param等于”flag.txt”，action等于”readscan”，就可以获得flag。
所以我们需要知道的是
hashlib.md5(secert_key +”flag.txtreadscan”).hexdigest()
这个的返回值。

@app.route("/geneSign", methods=['GET', 'POST'])
def geneSign():param = urllib.unquote(request.args.get("param", ""))action = "scan"return getSign(action, param)

通过/geneSign可以构建，令param等于flag.txtread，然后action是scan，这样我们就能获得正确的sign

Crypto1——xorz

题目如下

from itertools import *
from data import flag,plainkey=flag.strip("de1ctf{").strip("}")
assert(len(key<38))
salt="WeAreDe1taTeam"
ki=cycle(key)
si=cycle(salt)
cipher = ''.join([hex(ord(p) ^ ord(next(ki)) ^ ord(next(si)))[2:].zfill(2) for p in plain])
print cipher
# output:
# 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

给出脚本

import string
from binascii import unhexlify, hexlify
from itertools import *def bxor(a, b):     # xor two byte strings of different lengthsif len(a) > len(b):return bytes([x ^ y for x, y in zip(a[:len(b)], b)])else:return bytes([x ^ y for x, y in zip(a, b[:len(a)])])def hamming_distance(b1, b2):differing_bits = 0for byte in bxor(b1, b2):differing_bits += bin(byte).count("1")return differing_bitsdef break_single_key_xor(text):key = 0possible_space = 0max_possible = 0letters = string.ascii_letters.encode('ascii')for a in range(0, len(text)):maxpossible = 0for b in range(0, len(text)):if(a == b):continuec = text[a] ^ text[b]if c not in letters and c != 0:continuemaxpossible += 1if maxpossible > max_possible:max_possible = maxpossiblepossible_space = akey = text[possible_space] ^ 0x20return chr(key)salt = "WeAreDe1taTeam"
si = cycle(salt)
b = unhexlify(b'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')
plain = ''.join([hex(ord(c) ^ ord(next(si)))[2:].zfill(2) for c in b.decode()])
b = unhexlify(plain)
print(plain)normalized_distances = []for KEYSIZE in range(2, 40):# 我们取其中前6段计算平局汉明距离b1 = b[: KEYSIZE]b2 = b[KEYSIZE: KEYSIZE * 2]b3 = b[KEYSIZE * 2: KEYSIZE * 3]b4 = b[KEYSIZE * 3: KEYSIZE * 4]b5 = b[KEYSIZE * 4: KEYSIZE * 5]b6 = b[KEYSIZE * 5: KEYSIZE * 6]normalized_distance = float(hamming_distance(b1, b2) +hamming_distance(b2, b3) +hamming_distance(b3, b4) +hamming_distance(b4, b5) +hamming_distance(b5, b6)) / (KEYSIZE * 5)normalized_distances.append((KEYSIZE, normalized_distance))
normalized_distances = sorted(normalized_distances, key=lambda x: x[1])for KEYSIZE, _ in normalized_distances[:5]:block_bytes = [[] for _ in range(KEYSIZE)]for i, byte in enumerate(b):block_bytes[i % KEYSIZE].append(byte)keys = ''try:for bbytes in block_bytes:keys += break_single_key_xor(bbytes)key = bytearray(keys * len(b), "utf-8")plaintext = bxor(b, key)print("keysize:", KEYSIZE)print("key is:", keys, "n")s = bytes.decode(plaintext)print(s)except Exception:continue

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De1CTF-2019部分wp

目录

Misc1——We1come

Misc2——Mine Sweeping

Web1——SSRF Me

Crypto1——xorz

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