[crypto] Flippin_Bank

Is it normal that the server does not respond? Nvm I looked for a web interface and didn’t read the instructions… :-1:

I just can’t recreate what hex() does and how to do the decryption

Do we have to bruteforce this? Can anyone give me a nudge please?

dm me

I’ve never done this before so I had to do some research, and then analyze what the app is doing. This was an excellent learning exercise about this kind of crypto. I feel like I just did a homework assignment out of a cryptanalysis textbook.

No brute force required but it will require a bit of reading the code and analyzing aspects of the cipher algorithm to know what to manipulate without messing everything else up. You won’t need to get into intricate algorithmic details, just basic structure. It’s all right there though.

Kind of stuck. My cryptoanalysis only went as far as noticing common patterns with different username/password combinations…nudges would be greatly appreciated!

Would appreciate a little bit of help to this one as it is the first time I’m dealing with crypto and I would like to learn something new. Thanks

Thanks a lot to @alienum , I finally got it in the end, Nice challenge.

Great @P3t4 !! Very nice and educational challenge. However, i have some doubt. Someone to discuss about it?

If you have questions, feel free to PM me.

the name of the challenge is a big hint everyone :slight_smile: i suffered a couple of hours reading up on crypto until i stumbled on the attack that has to be done here

@federella and @Szkiel you can pm me if need it

Amazing challenge, definitely glad to have done this, thank you!!

I can modify the byte target successfully , but previous block gets messed up.
Any help?

python3 app.py
Traceback (most recent call last):
File “app.py”, line 7, in
from secret import FLAG
ModuleNotFoundError: No module named ‘secret’

:-/

Edit: I am stupid :slight_smile:
Edit 2: I am stuck hard as ■■■■… I think, I am at the last 20% of the challenge :neutral: Hope, someone could help me

Edit 3: FINALLY I got it! Thanks very much to my new best friends @alienum and @Civero for helping me and being very patient.
@P3t4: Very nice challenge! I learnt so much about python, crypto and how to use instances here :wink:

I think this challenge is hard for newbies in python and crypto, but it was very nice and I’m glad I solved it

Type your comment> @tXxc said:

python3 app.py
Traceback (most recent call last):
File “app.py”, line 7, in
from secret import FLAG
ModuleNotFoundError: No module named ‘secret’

:-/

Edit: I am stupid :slight_smile:
Edit 2: I am stuck hard as ■■■■… I think, I am at the last 20% of the challenge :neutral: Hope, someone could help me

Edit 3: FINALLY I got it! Thanks very much to my new best friends @alienum and @Civero for helping me and being very patient.
@P3t4: Very nice challenge! I learnt so much about python, crypto and how to use instances here :wink:

I think this challenge is hard for newbies in python and crypto, but it was very nice and I’m glad I solved it

Hey, I’m stuck on “no module named secret” and “Name FLAG not defined” too I’ve done pretty much everything else it’s just this bit… Can you please hint me to the right direction, am I missing any libraries or something :confused:

@hngrychckn412
Hey :slight_smile:
the module ‘secret’ and the variable ‘flag’ are used in CTFs to save the flag in an other module and not in the file, that you downloaded.
The script is running in an instance, you can start a new one within the challenge-menu in crpyto → Flippin Bank

Seen quite a few comments struggling with No module named 'flag':
If you wanna test locally, all you have to do is create a file called secret.py in the same folder you are trying to run app.py from, and in that file just type FLAG = "Anything really..".

This way, when app.py is trying to import the secret module, it will find something to import, and won’t throw an error. This way you can also define something to print, when you make your local instance print the flag. Hope this helps out someone :slight_smile:

Type your comment> @tXxc said:

python3 app.py
Traceback (most recent call last):
File “app.py”, line 7, in
from secret import FLAG
ModuleNotFoundError: No module named ‘secret’

:-/

Edit: I am stupid :slight_smile:
Edit 2: I am stuck hard as ■■■■… I think, I am at the last 20% of the challenge :neutral: Hope, someone could help me

Edit 3: FINALLY I got it! Thanks very much to my new best friends @alienum and @Civero for helping me and being very patient.
@P3t4: Very nice challenge! I learnt so much about python, crypto and how to use instances here :wink:

I think this challenge is hard for newbies in python and crypto, but it was very nice and I’m glad I solved it

can you help me out bro?

Hello, can someone send me a PM in order to give discuss this challenge and maybe give me some hints about it? Thanks

man I need nudge