Lacks's Level 2

Author:
Lacks

Language:
C/C++

Upload:
2026-07-10 17:20

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Platform:
Windows

Difficulty:
2.2

Quality:
4.5

Arch:
x86-64

Downloads:
615

Size:
19.00 KB

Writeups:
3

Comments:
15

Description

This is level 2 im uploading 1 - 10 crack mes

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Comments (15)
Writeups (3)

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dandelion_msla on 2026-07-10 22:11: [Click to reveal]

programcracker on 2026-07-11 00:53: a little harder than level 1, it was so nice getting it correct after finding out what the program needed me to do :D

jase282 on 2026-07-11 05:44: I'm a beginner, so the only thing I've managed to find out is that the password consists of 7 characters; the code also checks each character individually, so I think I'll be able to find the password now.

jase282 on 2026-07-11 06:19: Solution: set a breakpoint on `cmp cl, byte ptr ds:[r8+rax]` and examine the address held in `r8`. Navigate to that address in the memory dump, and you will see the following bytes: `28 3F 2C 3F 28 29 3F AB AB AB AB AB AB AB AB AB`. The `AB` bytes are junk data, but if we decrypt the sequence `2C 3F 28 29 3F`, we get the word "reverse," which consists of exactly 7 characters. To decrypt it, use the formula: `correct character = encrypted byte ^ XOR value`. In this case, the XOR value is `5A` (i.e., `xor cl, 5A`). Decrypting it yields the word "reverse." If you want to patch the program, you need to patch the character count check first, and only then the password validity check.

kungfufk on 2026-07-11 15:26: [Click to reveal]

Toji on 2026-07-13 09:33: [Click to reveal]

sh4man on 2026-07-14 09:31: [Click to reveal]

MichaelGalaxy on 2026-07-18 06:30: [Click to reveal]

zldp on 2026-07-18 11:03: [Click to reveal]

koltk on 2026-07-20 12:02: [Click to reveal]

kotsuge on 2026-07-21 21:02: [Click to reveal]

kcgaming on 2026-07-22 08:19: this was very hard for me to do, the password is "reverse" and its written at runtime which is xor and checked with input bytes

chopa on 2026-07-24 22:01: reverse it was hard

ludzof on 2026-07-27 23:59: [Click to reveal]

dotey on 2026-07-29 13:28: that one is hard for me...

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Solution by MoriartyPuth on 2026-07-14 17:40:

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Solution by hard1234 on 2026-07-24 14:07:
taking what is in memory pointed by r8 and xoring it gives the password

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Solution by defnotkira on 2026-07-28 21:35:
First crackme

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crackmes.one

crackmes.one

Lacks's Level 2