Questions tagged [crackme]

Little Puzzle Applications for Reverse Code Engineers, with the goal to break a protection scheme legally for exercise. These often have a lot of built-in security to prevent attackers from succeeding, at the end the reverse engineer often writes a so-called keygen (key generator) and a paper to show s/he succeeded and how.

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27 views

Radare2: Running executable from a specific point

I am using radare2 to reverse engineer a standard crackme executable. I have obtained the password, but now I need use the program to read & print a restricted file to which the executable has ...
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1answer
59 views

Password evaluated from the sum of ASCII letters

After analyzing the code, I have been able to understand and recreate the algorithm used to check if the password the binary takes is correct, but don't know how to solve it (or at least can't think ...
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72 views

Basic `angr` framework question- is something wrong with my solver?

I'm new to reverse engineering and I've just recently learned about angr, a framework that uses symbolic execution to get the input for a given output. I'm trying to complete a crackme using angr. My ...
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1answer
182 views

Segmentation fault after export binary file in Ghidra even without any changes [closed]

I trying solve some https://crackmes.one/ simple quests. I newbie on it. But after export binary file (even without any changes), when I run the program in the terminal, I get the message "...
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2answers
115 views

Weird function names in disassembly (crackmes)

I'm doing a really easy crackmes exercise (https://crackmes.one/crackme/5e4ec05c33c5d4439bb2dbea) and I can't figure out what the binary is doing because functions have extremely weird names. Here's ...
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1answer
105 views

Where can I find the QRC and QML files used for a QT gui application when reverse engineering?

I'm currently working on a crackme exercise for a GUI application using QT as practice. The application uses a server login authentication. I can see from the logs that the application output that ...
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1answer
77 views

Finding the correct input of an executable to print out the flag. IDA 7

I'm trying to understand the behaviour of the code below so I can determine what input will trigger the "YOU DID IT !~!" string (at the end of the program instructions): .text:00C21034 Buf= byte ptr -...
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35 views

Alternative APIs to hook instead of messagebox for message pop ups?

So i am reversing an app that pops up a message at some point, but its not doing this using messagebox i also tried to pause and then run to user code but didn't work, so what are some of the other ...
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389 views

How to change the title of a windows GUI app when patching? (the title that usually writes the application name)

So I'm trying to patch a binary (its a GUI app), and i want to patch the title of it as well when I'm patching it, and by title i mean the text that appears on top of the app that usually is the ...
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86 views

Z3 and If-logic

Z3 is a fantastic tool which helped me a lot! But sometimes I'm stuck on the binary code which implements custom If-logic. Recursive factorial function is good example of it: def fact(x): if x == ...
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1answer
253 views

Reverse getline(cin, text)

I'm trying to solve a crackme that was made in C++, and I was able to "recreate" a function call, through the library calls the program made. Here's the piece of code that I'm trying to reverse: ...
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2answers
71 views

Figuring out correct user input key from final key + generated buffer

I've recently gotten into reversing crackmes, and I seem to always fail at the ones similar to this. The final key that the program uses for comparison is not the key that should be used as input, ...
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323 views

In reverse engineering, what does it mean to “patch a file”?

I've been solving some crackmes, and every file that I download, in the "instructions" says: "Patching is obviously not allowed". What does that mean? And how does one patch a file?
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1k views

Can I trap SIGSEGV (on a Linux) and what are are the conditions to make it works? (for a crackme)

I'm writing some crackmes.one challenge and I want to write a challenge where the solution appears on a segmentation fault. (And you have to disassemble the code to find a way to segfault. It should ...
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1answer
511 views

How to embed PYZ.-00.pyz_extracted folder with entry .py file to generate exe file?

I have decompiled exe using pyextractor script and generated these files: PYZ-00.pyz PYZ-00.pyz_extracted gui pyi_rth_tkinter pyi_rth_multiprocessing pyi_rth_pkgres pyi_rth_win32comgenpy ...
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How to generate exe from compiled Python files?

I have extracted compiled files from exe (executable in windows) using PyInstaller Extractor script. In Resultant folder, i have got was pyc files bundled in pyz folder. Then I decompiled files (...
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183 views

Mysterious chunk of code in IOLI crackme0x06 challenge

I've been struggling to understand a very strange piece of x86 assembly code from the IOLI crackme0x06 challenge. Context But first of all, here is the context : I've successfully cracked the ...
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2answers
156 views

crackme disassembly - are these local variables ever initialized?

I'm working on a crackme, where the objective is to find the valid password given a program. I'm using radare2 to reverse engineering the program. To do so, I need to enter a password that forces this ...
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0answers
171 views

Password is right, but still wrong?

i am trying to find the password of a binary with radare2 - a crackme again :-) I already thought I've found the password ('pass'), but this seems to be not the right one. Or there is a trick I didn'...
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1answer
4k views

How to print the value of register with Radare 2

I am trying to solve this ELF - Ptrace challenge. I use Radare 2. This is the commands I execute to print the assembly code. radare2 ch3.bin [0x080482f0]> aaa [[anal.jmptbl] Missing cjmp bb in ...
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1answer
197 views

Radare2 does not display the entire assembler code

I am trying to solve this ELF - Ptrace crack me. Here are the commands I use : I start radare2 with the crack me as argument. radare2 ch3.bin I decide to go to the main and print the assembly code ...
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2answers
897 views

Are there any crackme sites made for cheat engine or to practice game hacking particularly?

I've checked several crack me sites and they're all on reverse engineering applications. However, I would like to practice reverse engineering by manipulating game values. The cheat engine tool ...
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110 views

Looking for crackme with full solutions [duplicate]

There are lot of crack me site. I looking for site that have lot of hard crack me/ malware to research anti debug/anti vm... but with full solution
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1answer
284 views

Disassembly - Why the CMP instruction is multiplying by 2 the value being compared

I'll get right to the point, I have a crack me program, that is a program with a password inside that needs to be found so that you can complete the challenge. I easily found the cmp instruction ...
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2answers
296 views

Automating a crackme solving process

Let's say we have a simple crackme, which asks for a password. After verifying it, eax will contain 1 if it is correct, and 0 otherwise. Is there a way (I am interested both in Linux and Windows) for ...
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2answers
199 views

How to reach functions triggered by non-standard buttons?

I've already read related posts such as: link1: https://stackoverflow.com/questions/24138087/how-can-i-set-a-breakpoint-for-a-button-click-using-ollydbg link2: How can I set a breakpoint for a button ...
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1answer
101 views

Keygenme - Key location

So I was messing with an interesting keygenme, written in C++, which derives the key based on the values of the OSINFO structure. Now, when checking for a valid key it uses the following instruction: ...
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2answers
538 views

How can I reverse this recursive function?

This is the python code I wrote of a simple crackme that I have reversed but I am not able to understand what the recursive function here does. def the_process(stored, inp, size): idx = 0 ...
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1answer
125 views

Static Offset in PE

I am making a crackme, that get's hexadecimal values and converts it to ASCII to get the password. The problem is I use a part of code into the main function to search the opcodes from .text section ...
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1answer
217 views

What is a “goodboy/badboy” [closed]

I'm confused and I'm trying to follow the Radare 2 Crackme Challanges. In it, they say, This seems to be a goodboy/badboy. Is a "goodboy/badboy" lingo for a specific thing, and if so what?
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1answer
197 views

Example of key fishing with OllyDbg logging? [closed]

I'm new to reverse engineering. Can you give an example of a crackme to do "non-hardcoded" key fishing and how to log the x86 registers to spot the generated key?
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1answer
530 views

brute force remote nop sled memory address

ELF x64 binary on a remote server communicates via simple socket server in C. After overflowing the buffer (total buffer is 2000, password buffer is less), overwriting the RIP, filling with NOP sled (...
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1answer
351 views

Solving method of DLL crackme

I was given two DLL files (link) . The task is to get the flag from them. First what I've done - opened the first file (called original) in IDA and found the function called _GetFlag. As I understood,...
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1answer
890 views

Reverse engineering of Managed C++/C# CrackMe

I'm reverse engineering the CrackMe which is written on Managed C++/C#. Arguments are "string" (email in this case) and "serial". Serial is somehow depends on string and I need to understand how. I ...
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1answer
159 views

Weird looking assembly-code bunch

I am currently analysing some crackme with Olly and IDA. Initially it was packed. I managed to find the OEP (a JMP soon after POPAD and right before a bunch of nulls): 0040E978 . 53 ...
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1answer
1k views

Reverse engineering the virtual machine based crackme

I am currently working on some crackme, that has implemented an obfuscation technique, virtualisation. The virtual machine inside this crackme is a huge switch-case block (over 130 cases in it). I ...
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3answers
30k views

Crack Me Material

I'd like to get started with reverse engineering. Some years ago I've seen many many program, so called "crack mes" to crack. When I searched for some this week I've found none. My Question is, can ...
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1answer
312 views

Practicing what SHOULD be a simple crackme. Program calls strlen() but never returns

I'm trying out a crackme from the "LSE CTF" called "Blue Box" worth only 10 points. I've attempted this inside GDB and radare2... It is very simple, takes one argument and first checks to make sure ...
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1answer
158 views

Length requirement on IOLI crackme input

So I'm just starting to learn reverse engineering and binary exploitation and going through the RPI course where the first lab set is drawn from the IOLI crackmes available on Github. I could post all ...
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2answers
713 views

c++ version of MOV AL,BYTE PTR DS:[ESI]

I'm writing a keygen for a crack-me exercise. I have a problem with handling byte assignments the crack-me performs several times using instructions like MOV AL,BYTE PTR DS:[ESI] (move byte from ...
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1answer
818 views

How to crack windowed crackmes?

I am starting with reverse engineering/cracking with advanced knowledge about programming and functioning of the operating system and I saw a whole series of lena151 Lenas Reversing for Newbies but I ...
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1answer
2k views

Why doesn't the breakpoint get hit in gdb?

I was following the writeup of the challenge tehran. If I set a breakpoint 0x804bade, it never gets hit for the following input. begin() { fillout(0x8048000, 16384, 7); puts("%144c%n", 42, ...
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1answer
84 views

Where can I get systematic problems and solutions for debugging?

I know PEFile headers, assembly language, and other basic stuff. I am looking for some site or book which systematically teaches me debugging and reversing. Something like "Let us C" for C language. ...
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1answer
10k views

Where can I find CrackMes for beginners? [closed]

I'm interested in learning. Where can I find CrackMes for beginners? Especially ones with answers.
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1answer
797 views

Decrypt / Decode / Decompress Proprietary File

I am using a 3rd party software that stores templates for ID cards in a database. I believe the templates are in xml format but are encrypted / encoded / compressed in the database. Each encoded ...
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1answer
1k views

How does serial number is checked in this crackme?

I am trying to reverse engineer a crackme exe. I have managed to find the function that checks serial number based on email input. So, 4 arguments are pushed to the stack (esp) which are the input ...
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1answer
758 views

What are the results of this sbb instruction?

I'm doing a crackme to learn some reversing, and I stumbled upon this code generated by C++ MFC: sbb eax, eax sbb eax, -1 test eax, eax jz exit Before that code a comparison is done, such as cmp al, ...
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3answers
12k views

Edit codes in .Net Reflector with Reflexil (Compile Window)

I'm Using .Net Reflector with Reflexil to edit or view .net Assembly codes. I see this picture in reflexil.net: It Shows the "Compile" window. How can I see this window and edit codes?
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1answer
205 views

Can a keygen be created for this protection algorithm? [closed]

I reverse engineered a program protection algorithm and got the result in this source file I wrote, but I would know this type of protection. Please tell me what is the type of this protection ? And ...
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2answers
8k views

Fixing corrupt ELF header field “e_shnum” for use in GDB

If the ELF header which usually can be read using readelf has been manually manipulated, let's say by increasing the value for the "Size of section headers" the binary still can be executed and works ...