Questions tagged [c]

General purpose programming language that uses the procedural and structured programming paradigm.

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Can IDA generate C code for ASM assembly wihtout the binary

Lets say I have this picture of some assembly: Now I know how to manual tranform this assembly into C code because it is small but is it possible for IDA to convert this into C code? Ideally I would ...
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2k views

Reverse Engineering a 8 bit CRC checksum

I am trying to create a communication interface using C Language to an Air conditioning system, after analyzing the data packets I have identified that the data packet is consist of an 8 bit CRC (I am ...
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What is happening with this *param_1?

I am a bit of a starter, so bear with me as I can't find the answer through Google (a common thing in Ghidra work I noticed so far). I have a function that seems to read like it is a Constructor. But ...
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70 views

Confusing objdump with data as code

I am trying to confuse objdump to solve the first exercise of chapter 6 in Practical Binary Analysis. Admittedly I am super weak with inline assembler but I made a best-effort attempt and tried to get ...
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81 views

How to create an algorithm in C...(or C# or C++, basically in "a programming language")

After a LOT of sending challenges and recording the responses I've 'broken' the "encryption" in my car's immobiliser...the reason for doing it is so I can use the engine and transmission in ...
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How do I disassemble mips .o object files in ida elf 64bit

So I’m trying to disassemble some object files in mips. I use IDA 7 on windows. These object files are loadable kernel modules. Mipself64 Is What ida auto sets to when they are dropped in. I’d like to ...
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52 views

Trying to call the Exit Shellcode in a c program

#include<stdio.h> #include<stdint.h> char shellcode[] = "\xb8\x3c\x00\x00\x00" "\xbf\x14\x00\x00\x00" "\x0f\x05"; int ...
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120 views

Delphi mt38 CRC (Tricore 1766 Arch)

I want to calculate CRC32 for Delphi mt38 and found the below assembly algorithm and converted it to C. It seems that this algorithm is defined for n = 256 or 1024. I want to calculate CRC32 for n = ...
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346 views

Some obstacles in reversing a JNI Native library

I deleted my last question (it was not still answered and none's effort was wasted) as I got back and thought to re-read JNI documentation, to find I misinterpreted some bits. Things are now clearer ...
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94 views

Static binary instrumentation

I am working on a class project. I need to find out static features of a program (without executing it). Backward branches (loops) Conditional branches (potential threads with load imbalance) ...
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168 views

Reconstructing struct/union-based IPC protocol wire format

I'm embarking on my first reverse-engineering adventure. I think I've picked a rather dense piece of steak to start out with. I have three C programs which communicate together using an unknown IPC ...
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224 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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510 views

Illegal instruction fault in stack based buffer overflow

I wrote this short C program to practice buffer overflow exploits: #include <stdio.h> #include <string.h> #include <stddef.h> #include <inttypes.h> char *decode(char *s){ ...
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90 views

Decompiled code calls a function with unitialized variables

I'm working on decompiling the scripting engine from the game Rayman 2. It's going pretty well, but I'm getting stuck on a particular function which calls another function with arguments that aren't ...
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995 views

How to decrypt .jpg files of comics app in a C Program?

I'm trying to decrypt jpg images of comics I purchased in my comic reader app on android but neither I can view them (after copying from SD card to Windows desktop) nor can I convert them to pdf to ...
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1answer
1k views

Calling Swift 4 methods from C

I have earlier been able to call Swift methods using a function pointer from C, and providing the appropriate arguments because the calling convention was the same. Unfortunately this no longer works....
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58 views

Fighting programs that don't respond to Send/PostMessage-based input

This can be difficult to ask because 1) people assume this is necessarily malicious and 2) unrelated but effectual techniques like GetForegroundWindow can make this impossible to answer. So, to keep ...
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297 views

Extracting information from a windows executable

I've been given the task of writing a functional clone for an executable since we don't have the source code. None of the .NET tools at my disposable recognise it and loading the thing into a text ...
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362 views

IDA Pro .til files backward compatibility

I read in the IDA Pro Book that you may use till.exe to parse header files and create standalone .til files which can be made globally available by copying them into <IDADIR>/til. This ...
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207 views

How get a full memory dump of a running specific process from kernel mode by driver?

How can i get a full memory dump of a running specific process from kernel mode by driver on windows operation system?
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562 views

Define new code section in assembly code to compile ELF binary

I defined a new code section in my assembly program, which is going to be compiled into 32-bit ELF binary, on x86. I use the linker scripts to assign a specified address for this new code section, it ...
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74 views

Creating shared object library to switch out loaded methods

Is it possible to create a dynamic library libXXX.so with android ndk that has a function that switches out methods in loaded classes in the dvm and call it from any apk ? There are functions within ...
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1answer
595 views

Injecting exe file into process fails on windows 7 but works on windows 10 / Execution library function fails, access denied

I'm trying to inject my executable payload into remote process. I allocated memory in remote process, I converted raw payload using RVA addressing. I applied relocations and imports table. When I'm ...
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1answer
617 views

Problem to understand execution of payload (shellcode)

I know that there are lot of (good) tutorials regarding this topic, but after reading them, I really cant follow their thoughts (e.g.: Smashing The Stack For Fun And Profit): The problem is that we ...
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57 views

Ghidra - search for library usage?

Using Ghidra: if library A imports library B, is there a way to search for all function calls from A into B? And more specifically: if B exports function foo, how can I find where that specific ...
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40 views

How do I view registers at a specific point of a binary's execution?

I have a binary that I'm attempting to reverse engineer to find a flag. From using ghidra I have found that the flag is stored in the program at a point called "check" and then run through ...
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58 views

How to hack fan control speed?

So I recently bought a new laptop (Acer Aspire A315-57g) on which I found that the cooling solution wasn't optimal, and I decided that I want more RPMs from my fan. However, I wasn't able to find a ...
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1answer
116 views

MIPS assembly to C code

I think I'm really brain-dead and am not really sure what to do next, but I am trying to manually convert assembly code to a C program. It's not really working, but I'm not sure what is wrong. I would ...
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48 views

How to maintain function ordering in an executable when replacing machine code with C step by step?

I am working on reversing a DOS game consisting of 16-bit MZ EXE files. I was able to determine the exectuables were generated by Microsoft C v 5.10, and loading the signatures from the static ...
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52 views

How to reverse engineer structs in radare2?

Is there any way to indentify structs in radare2? when i tried to look them, they look like normal variables, i seen people using td and tl command but I don't know how to use them. If you know please ...
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57 views

Radare2 is showing weird disassembly as compared to disassembly of gcc

Today i was playing around with c code in r2. I compiled a file which had the following code. #include <stdio.h> int main(){ int a=9; float b=1.1; int sum; sum = ...
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33 views

HexRay API - Programatically rebaseing program on firmware

I am working on several firmwares (mostly ARM and PPC) that have no structure that IDA can decipher and so far I have been guessing BASE address until the functions and strings align with what I see ...
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67 views

Reverse an encryption algorithem in APK .so file

I try to reverse a cipher algorithm (I guess Tiny Encryption Algorithm (TEA)) in an android application. But I have a serious problem in initializing arguments. How I can understand that I have ...
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29 views

What is the meaning of call ds:ApiName[registry*constant] in IDA .asm files?

I have a dataset of .ASM files generated by IDA (dont have the corresponding file) now there are a lot of calls like this : .text:00637114 5F pop edi .text:...
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190 views

C166/C167 code analyzing

Recently I try to reverse piece of assembly code that written for C166/C167 Arch. But I have a problem with some places for convert to C code, such as: loc_1892: mov r9, #4 add r9, r0 mov ...
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50 views

Develop a Hello World plugin for Ollydbg

I wanted to write a plugin for Ollydbg 2 which shows just a simple message. I write the following one but it doesn't load in ollydbg. I am using ollydbg 2 and my DLL can't load by it. Where is the ...
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47 views

Python based static c analysis tools

I want to analyze some open-source C code, and I'm looking for a static analysis python library for C, preferably open-source. Any ideas/suggestions, based on your experience?
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54 views

Performing Buffer overflow in Linux

I have buffer overflow in a program i check(it is an array of pointers, and i can overflow the data in the first pointer), but the data i can write is not on the stack, it is on a space the system ...
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66 views

What memory security settings are needed to allow a basic buffer overflow on Fedora 25?

I'm having a rather difficult time determining what memory security settings need to be adjusted on a fresh install of Fedora 25 in order to perform basic buffer overflows in the C language. As a ...
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320 views

How to pass Obfuscated Elf binary to gcc optimization end

Currently I have a 2000+Line function to reverse engineer with many redundancies and appears to be obfuscated. It their a way to pass to pass this binary to gcc or clang to reassemble it and optimize ...
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73 views

dlmalloc free pointers

I was looking at the implementation of "free" in my current dlmalloc(both the source and the disassembly). However, I could not find the code section the inserts the FD and BK into free chunks. What ...
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1answer
94 views

Translate ASM code x86 32 bits in C

I have a exercise which i can't resolve it, and i need help. If anyone can help me it would be great. I have the next ASM code in x86 32 bits which i need to translate in C language: Dump of assembler ...
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1answer
207 views

What is, and why, "byte[ ] + number" in this IDA pseudocode?

This is a decompile of an .so file, so it originated from C or C++. Can you kindly try to explain to me what this does? How would one rewrite this into readable code? I don't mind any programming ...
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1answer
445 views

How can I convert the following assembly code to pseudo code?

I got the following disassembly code in IDA pro. I really find it hard to convert it into pseudo code. push ebp mov ebp, esp sub esp, 14h mov dword ptr [ebp-14h], 1 mov dword ptr [ebp-10h], 2 mov ...
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1answer
1k views

Aside from Assembly, should I learn C or C++?

With Malware/Virus analysis being heavily dependant on one's ability to read the the Assembly Code generated by the Disassembler... being familiar with the Assembly Language is naturally the most ...
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1answer
431 views

winmain reversing the assembly to c code

this is I got so far #include <windows.h> int WinMain(HINSTANCE hlnst,HINSTANCE hPrev, LPSTR lpCmd,int nShow){ int k =0; int j= 0 ; MessageBox(0,"crackname","",0); int i; ...
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1answer
429 views

Hiding shared library calls from ltrace

I am trying to implement some antidebug methods. Although I have encrypted texts, ltrace reveals them, for example: strstr("Name:\tltrace\n", "ltrace") A solution would be static linking, but I do ...