pranav's SecureSoftware

Author:
pranav

Language:
C/C++

Upload:
2021-02-13 06:20

Download

Platform:
Windows

Difficulty:
1.8

Quality:
4.8

Arch:
x86

Downloads:
18

Size:
8.96 KB

Writeups:
1

Comments:
24

Description

This will pretend as a legit software, and ask for a Key to 'unlock' the file. You will also be given the data to generate the Key. You should create and place the Key correctly to 'unlock' the software. You are not supposed to debug or patch the 'software'. Password: crackmes.one (default for all crackmes - check FAQ) IMPORTANT: READ ALL THE DOCS BEFORE LAUNCHING THE Crackme! By Pranav

Comments (24)
Writeups (1)

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4epuxa on 2021-02-20 17:05: [Click to reveal]

pranav on 2021-02-21 06:09: 4epuxa just 2 numbers?

4epuxa on 2021-02-21 09:09: pranav Yes, because the dividend is 0xCF and 0xFF, and then there are zeros. We need these two numbers to be divisible and the remainder is 0x36. We divided them and received the remainder of 0x36, and since we have more than 0x00, the program simply transfers them to the message of successful registration

Scopes on 2021-02-24 13:50: just jmp to loc_401703

pranav on 2021-02-24 14:45: Scopes how did you do that? Did you patch the crackme?

ragnar_crackbeard87 on 2021-02-25 13:08: Hello. Are there anti-debugging tricks involved? I don't seem to see any but if I try to debug this in say x32DBG or ollydbg it won't properly run. I see there are new threads being created but in x32DBG for example it never returns from a simple call to Sleep. @ 0x00401675 it calls sleep, as shown in this picture but if I hit step over, it exits the program. And doesn't run as it does when not in a debugger. https://imgur.com/a/QMm8PxD

pranav on 2021-02-25 15:47: ragnar_crackbeard87 yes, there are anti debugging/patching implemented. You can disable it if you wanted, although it is not preferred. You are generally expected to use static analysis to reverse the crackme

ragnar_crackbeard87 on 2021-02-25 17:07: Okay, pranav. I see where to do it. But I can't figure out exactly what byte is being read and returned during the calls to fread when it reads the AUTH and KEY files. I'll keep trying to do it with IDA. However, could you tell me which tricks are utilized so I could google them and practice removing them for future scenarios, please?

ragnar_crackbeard87 on 2021-02-25 19:40: pranav, I got the answer. My first crackme back after quite awhile so my brain didn't realize to check the auth file for myself and to write a binary file for my answer. Not just put my answer into a regular txt file lol. Thanks! I'd still like to know how to reverse the anti-debugging tricks if you could teach me!

pranav on 2021-02-26 01:49: ragnar_crackbeard87 well, you have to follow the thread start after printing InitialChecks.. It's actually an anti patching mechanism, you have to prevent it from executing. For more details, join the website discord server and find me as PranavAppu007.

ali0gamer on 2021-03-03 18:51: This is really easy just create two files: .key and .auth, then put '\0' in the .auth and run the program.

pranav on 2021-03-04 04:30: ali0gamer well if it's really easy then generate a valid .key file instead of patching the .auth file. You were actually supposed to do that, although I'll allow patching on .auth for now

pranav on 2021-03-04 04:31: It is intended to me a keygenme

ali0gamer on 2021-03-04 06:27: Ok. Thank you for the challenge.

mohammadali on 2021-03-14 16:11: hey man i just wanted to reply for what u said to me on: https://crackmes.one/crackme/6043d8b833c5d42c3d016d32 thanks, and dont give a fuck about people saying ur doing things bad and wtf, just be u man, i honestly would love to reverse engineer executables like the way u do, but i have a lot of problems with my ida and idk, i just like patching. good job on what u did, i am posting this here i figure u will at least may read what ppl cmnts so here i am, i dont have a discord account but we can chat on a mail of mine, ill send u my telegram account.

mohammadali on 2021-03-14 16:14: and im targeting your crackmes for a while, when i patch them ill comment the link of the patched version on a post of yours, but im kinda busy college shit and a lot of math homeworks , so ill start next week. just track my comments to a github link and then youll find my email, have a nice day now !

mohammadali on 2021-03-14 16:16: ill be looking for a reply here so just type something to make sure u read them :)

pranav on 2021-03-15 02:53: thanks!.. Well, you can join the discord server, and I'm there along with a very good community. It's fun!

pranav on 2021-03-15 02:55: Me too, didn't have a discord account at first, but it's worth it. I'm also kinda busy, so I'll email you when I get time.

mohammadali on 2021-03-15 03:52: okay ill give it a try !!

noobvariable on 2021-05-14 15:26: best for practice. thank you very much

puelo on 2021-06-27 20:07: Nice crackme. bytes = bytes out of .auth File for (byte in bytes) { /// solve this for keyByte and write into .KEY file byte % keyByte = 0x34 }

DeadShot on 2021-07-24 08:38: again fun to do crackme, very easy

fewnity on 2023-06-29 01:02: You can modify the .auth file it's way easier ahah

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Solution by lfanew on 2021-05-16 06:30:

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