kvfs's my first crackme

Author:
kvfs

Language:
C/C++

Upload:
2024-09-27 01:43

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Platform:
Windows

Difficulty:
2.6

Quality:
4.0

Arch:
x86-64

Downloads:
22

Size:
20.00 KB

Writeups:
1

Comments:
15

Description

Goal: Find out how does the password generates. Hint: - Minimum 3 chars. - Depends on input for password generation. As it's my first crackme/keygen idk what else should I say here. Anything needed, don't doubt to ask me.

Comments (15)
Writeups (1)

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salpymec on 2024-10-01 19:30: Mk là gì vậy ?

kvfs on 2024-10-02 22:57: You have to find out how does the password check works. It's not a preset password, it depends on the password you input. For example: Password: abcdefg (Password incorrect) Password: aaaaaaa (Password correct) Password: bbbbbbb (Password correct) You have to find out the formula for the password's generation.

t0xic11 on 2024-10-03 15:28: I made the pseudocode: #include #include #include #define MAX_SIZE 100 int sequencia(char *str){ int count = 1; char atual = str[0]; for(int i=1; i = 4){ return 1; // Foi } } else { atual = str[i]; count = 1; //res } } return 0; } int main(){ char *input = (char *)malloc(MAX_SIZE * sizeof(char)); if(input == NULL){ fprintf(stderr, "ERRO AO ALOCAR\n"); return 1; } memset(input, 0, MAX_SIZE * sizeof(char)); printf("Input pass \n"); fgets(input, MAX_SIZE, stdin); while(1){ input[strcspn(input, "\n")] == 0; if(strlen(input) = 4){ memmove(input + 10, input, 4); input[15] = '\0'; } if(sequencia(input)){ printf("Sucesso \n"); }else{ printf("Try again \n"); } free(input); return 0; } } I only need 4 identical characters

xorkey on 2024-10-05 12:27: Good, but much easier than difficulty 3. Continue your journey, kvfs.

kvfs on 2024-10-05 21:52: t0xic11, that's is not the solution, but is kinda close. If you try doing "aaaab" as password, it will be incorrect.

MadKalashnikov on 2024-10-13 17:26: Sorry if im way too beginner for this challenge, but im trying to look for the "Input Password" print line in Ghidra, not finding anything. why?

_int2eh on 2024-10-13 18:14: Excellent Crackme! I broke down each function hand by hand until I found the exact checking part, and understood that to reach "Access Granted", the two blocks of memory compared in "memcmp" must be equal for EAX = 0 and the "test" instruction be valid , skipping the "jne" instruction

kvfs on 2024-10-15 15:41: MadKalashnikov, all strings are encrypted using xorstr. That's why you can't easily find the strings in ghidra or ida

vishalkumar2806 on 2024-10-17 13:33: so you want us tomake a key gen on this or wht

kvfs on 2024-10-17 18:44: vishalkumar2806, the keygen is optional. You have to find out the algorithm for the password generation and you can make a keygen if you'd like to

Hackantrick on 2024-10-18 17:44: cannot open zip file its password protected and crackmes.de or crackmes.one is not working

Nuxi763 on 2024-10-20 14:35: If input size is even it will generate a reversed password , if we assume input is : Test it will generate : tseT. so if we Enter TesttseT, it will generate the same, so it will grant access. If input size is odd, we assume input we wanna enter is : Crack It will generate kcarC, so if we wanna get access with odd input size, we have to enter CrackcarC. In short : It generates password with reversing entered input.

kvfs on 2024-10-21 19:25: Good job Nuxi763!

upfeed on 2024-10-24 12:38: upfeedeefpu seems all the same from either side

NN305 on 2024-10-26 16:34: It's kinda hard for newbies like me to solve this. Where I can find easier tasks to solve on which I can practice?

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Solution by Benbaby on 2024-12-22 04:38:
Explain & source code of keygen. Thanks

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