Project Sekai - ✅-reverse-homework-help

Homework Help - 500 points

Category: Reverse Description: I wrote a program to solve my math homework so I could find flags. Unfortunatly my program sucks at math and just makes me do it. It does find flags though. Files:

https://wolvctf.io/files/7988c856d4ed0e29d8f49ca53c2df670/homework_help?token=eyJ1c2VyX2lkIjoyNjgsInRlYW1faWQiOjE3MCwiZmlsZV9pZCI6MTl9.ZBTG7A.EMUm8j88Rh5OZSxPlXpx-Gdd7As

Tags: ct#3469

Sutx pinned a message to this channel. 03/17/2023 1:00 PM

@Utaha wants to collaborate

feels like we need remote connection otherwise no FLAG value?

@irogir wants to collaborate

hmm FLAG is read in stack check

13:15

I'm a confused rev beginner peepoo

you can solve this?

lemme try lol

nice

@TheBadGod wants to collaborate

seems like the flag checker is in stck check fail

13:25

so I can either just reverse that part

13:25

or some how convince gdb to lemme smash the stack

13:25

I'm wondering if there's easy way to do the second method

13:25

I'll try rev the first part

b'wcctf{+m0r3_l1ke_5t4ck_chk_w1n=-}'

13:29

x = bytes.fromhex("41140017121d50465d42416c335d5a0e3a6a41405708343c0b033428465f531050")
a = 54

from pwn import *
f = b""

for i in x:
    a ^= i
    f += p8(a)
print(f)

13:29

duplicated the c in there for some reason

TheBadGod

used /ctf solve

✅ Challenge solved.

where did you get the logic?

from the stack check, like utaha said

13:32

it basically then checks that every byte in FLAG equals the byte a, so i just appended all of them

13:32

also: does the bot not know about the archs challenge?

so fast

13:35

how do you dump those hex so fast lol

numpad

~~@sahuang can I have tryout reverse tag~~

1

i can work with you on the next rev, i think TBG will do it in hard->easy order

will work on archs

its pulled now @TheBadGod

cool thanks