pranav's SecureSoftware v1.5

Author:
pranav

Language:
C/C++

Upload:
2021-03-11 07:10

Download

Platform:
Windows

Difficulty:
3.0

Quality:
5.2

Arch:
x86

Downloads:
232

Size:
9.61 KB

Writeups:
3

Comments:
16

Description

This will be a little harder than the previous one, not due to the algorithm itself, but due to a bit harder to understand. Please DO NOT paste solutions as comments, as it might spoil the fun. Please make sure to upload a Writeup after you cracked it. I love reading Writeups!! Make sure you completely read the readme, to completely understand about the challenge. Good Luck! Password: crackmes.one(Read FAQ) C based crackme(Not C++)

Labels ?

Anti-debugging IsDebuggerPresent Timing (rdtsc/GetTickCount) String / data encryption Anti-tamper / integrity

Comments (16)
Writeups (3)

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mohammadali on 2021-03-22 12:00: well, i took a look, your calling isdebuggerpresent and placing a anti-patching tech that will put 1 in case of a debugger detected, and you'll compare it later, i think you did the same thing for -i / -u ... ill crack it later, i have some math homeworks to do rn so no re for a while :(

pranav on 2021-03-23 05:20: hey! Well there is a lot of stuff in it! Make sure you read the Readme fully.

mohammadali on 2021-03-24 09:25: i was able to disable the anti-debugging and the "-i" parameter, now when you run it, it will ask u directly about the key, but im stuck in a part that it will exit after entering the key, i cant figure out where is the "success message", not because its encrypted, but because there is a strange loop at some point after asking for the key that will exit although there is no such call to exit !!!

mohammadali on 2021-03-24 09:37: it is using calling printf but when it does it is exiting, thats why its not printing "enter the key", even though when i run it inside ida it did show the message, and running it directly will show the same message, idk what is happening

mohammadali on 2021-03-24 09:39: here is the link, post an issue, or contact me via mail on github, cz i really want to figure it out :) https://github.com/ORCA666/patched-files/tree/main/pranav's%20SecureSoftware%20v1.5

pranav on 2021-03-25 17:36: mohammadali Are you sure you defeated all the anti-debugging protections?? :wink:

pranav on 2021-03-25 17:39: also try to get a real key in addition to patching it, so that the key works in an unpatched version... And for others no the patching doesn't count as a solution

mohammadali on 2021-03-26 03:45: @pranav okay my man, we'll see, ill be trying couple of days later cz i have some tests and i dont want to mess up, but try my crackme ? its level 4 but i think it is level 3 or something in between, if you cracked that ill crack this :|

4epuxa on 2021-03-28 12:29: This is your hardest crackme, it's great! The main difficulty for me is a bunch of variables. Quite interesting counts of auth file integrity and function integrity counts. Overall, crackme was a success! Generating a password is not too complicated, the most difficult thing is to understand what is happening where what is changing. Success! The program has been unlocked!

kondeti on 2021-04-14 07:18: A very nice crackme, I have written a keygen which works for me. I will try to submit the solution when i got some spare time. You can find keygen(in python) at below link. https://pastebin.com/Dmsmg1Ta

pranav on 2021-04-19 09:16: thank you @giacomo270197 for your comprehensive solution. One of the best solution write ups I have ever read.

puelo on 2021-06-29 21:32: Again a very nice crackme. I've solved it statically, but with a decompiler. My solution in the end was to only replace two bytes inside the authdata file. Settings the first to the calculated/needed byte and the second one to 0x00, so that the check at the end would only consider this one byte. I also updated the checksum, which wasn't too bad after understanding how it is calculated.

DeadShot on 2021-07-26 19:19: Solved using full static analysis, by doing so I also learned about anti-debugging techniques used, anyway very good challenge and definitely a lot easier than mentioned.

ReedOnly on 2022-06-14 16:59: Solved with static and dynamic analysis, including anti-debugging bypassing.

YULONG on 2026-08-06 15:28: [Click to reveal]

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Solution by giacomo270197 on 2021-04-10 16:10:
The solution to the main question of the crackme

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Solution by g3chantr on 2022-01-30 17:37:
A really nice chall !! This solution contains a detailled analyse and a python code to generate the key !

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Solution by ReedOnly on 2022-06-05 09:17:
https://reedonly37.atlassian.net/wiki/spaces/WRITEUPS/pages/33035/Crackmes.one+-+pranav%27s+SecureSoftware+v1.5+-+writeup

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