Questions tagged [c]
General purpose programming language that uses the procedural and structured programming paradigm.
262
questions
0
votes
0answers
16 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:...
0
votes
1answer
32 views
Application only Crashes on CPU with SHA extension
Have an application that only crashes if CPU has SHA extensions. After some investigation find a hashing routine that only occurs if CPU has SHA extensions.
I'm trying to confirm if issue is with ...
-1
votes
0answers
29 views
String to instruction
I am more into reverse engineering more than binary exploitation. I like to bypass jump instruction. but sometimes, I get very frustrated when I don't find the jump instruction via a string.
for ...
5
votes
2answers
936 views
Difference between Main and Entry
Sometimes, I see while disassembling a binary that there is the main function. but sometimes, instead of main, there is entry function.
I want to know what is the difference between entry and main.
0
votes
0answers
28 views
Doubts about a pointer in a DLL
I am working with the dll of a software in which I am not with access at the moment, analyzing the source code in static analysis tools, I realized that it receives a pointer as one of the parameters, ...
0
votes
0answers
73 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 ...
1
vote
1answer
46 views
How to restrict angr to printable characters
I have a binary that scanfs and then does some checks and returns either FAIL or SUCCESS that has SUCCESS for multiple inputs. Although only one of the inputs has only printable characters. How do I ...
0
votes
1answer
47 views
Buffer space in C
I was wondering if there is some way to get information about buffer size via reversing the binary, created in C language. can we also know how many buffers we have created while writing that script.
...
2
votes
1answer
119 views
How do we decompile java so easy?
I have seen a lot of videos where everyone is decompiling the jar files so easily. but I learnt that we cannot decompile any compiled file so easily. I have a little bit of experience in Gidhra. I ...
0
votes
1answer
70 views
2 byte format string attacks
Protostar
I was doing the protostar format string (3rd challenge). where we have to change the value of a variable target with format string buffer overflow. so, I came up to this medium article: ...
0
votes
1answer
73 views
How to find function start in stripped binary?
Given C code, are the function addresses from the ELF the same as those in the stripped version?
I don't have any specific code in mind. Just trying to learn in general how to find the function ...
0
votes
1answer
74 views
how could i follow a system call from a dll -> kernel driver syscall
basically i would like to follow (system calls / internal calls) that basically lands in the kernel i would like for example to debug a specific dll ex : ntdll.dll and follow it to (NtXXX) function ...
2
votes
3answers
95 views
Intercepting game function with C and Assembler, game unstable with minimum changes
I am reverse engeneering a really old game (Mu 97d) for the sake of adding new things to the game.
What I am doing is intercepting the game with a DLL, and in the DLL do the calculations so I can add ...
1
vote
0answers
133 views
which has better pseudocode? IDA or Ghidra [closed]
I would like to know which of the two has a better pseudo code generator in C, IDA or Ghidra, if possible, point out the strengths and low points of each one.
1
vote
1answer
68 views
Is Ghidra's decompilation of ARMv7 strb.w instruction broken?
I'm currently disassembling some firmware, when I stumbled across the following code snippet produced by Ghidra (the names are already my own ones):
void memset(byte *addr,byte value,int count)
...
1
vote
2answers
60 views
Newbie problems exploiting a format string vulnerability
I encountered a print format vulnerability challenge in a CTF. I don't know anything about these vulnerabilities, so I'm working my way through Saif El-Sherei's format string exploitation tutorial ...
1
vote
2answers
68 views
Simple angr example not working
I am trying to learn angr from beginning. Due to lack of simple tutorials I programmed my own little executable which angr should solve.
The C code looks as follows:
#include <stdio.h>
#...
1
vote
1answer
163 views
Ghidra scripting get information from decompile window
I am using Ghidra and when clicking for example in the decompile window on a specific raw, it change the cursor in the assembly window to the exact location in the assembly. Is there any option to do ...
0
votes
0answers
40 views
Parsing C header files from DWARF Debug File
I have a Linux executable that has a linked .debug file containing DWARF debug info and I would like to find a way to parse C headers for types defined in the executable. Using gdb and ptype I can ...
1
vote
1answer
34 views
Why does this x64 stack have other bytes and seems to be in reverse order?
I wrote the following small C program and you can also see the stack in the screenshot. My question is twofold:
How come there are entire rows of other data between the 3 stack strings?
Why is my ...
0
votes
0answers
42 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 ...
1
vote
1answer
238 views
Ghidra error when edit main signature function
I'm new to ghidra.
I download the easy_reverse from crackme.one and open the executable file in ghidra.
When I'm trying to edit the main function signature I get an error: Can't parse name: argv[].
I ...
0
votes
1answer
73 views
How can I debug open source C code for Linux?
I want to debug & reverse engineer open source code such as this project. I usually use CLion to write and debug C code on Linux. I've also used GDB. What steps do I need to take to download a ...
2
votes
1answer
101 views
Why is there no call to strcpy in assembly?
I try to better understand assembly and currently playing around with some compiled c snippets.
I have the following snippet:
#include <stdio.h>
#include <string.h>
int main() {
char ...
0
votes
0answers
49 views
What does the file pointer of fgets actually point to in linux?
So i was reversing a 64 bit ELF binary, and it did a call to fgets, and based on documentation the third argument of fgets is a file pointer.
now the weird part was that the third argument in this ...
0
votes
0answers
46 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?
-2
votes
1answer
72 views
Hash from pseudocode [closed]
What is the hash? Generated from ida pro
int __fastcall hash(_BYTE *a1)
{
_BYTE *v1; // r4@1
int v2; // r5@1
int v3; // r6@1
v1 = a1;
v2 = 0;
v3 = 1;
while ( *v1 )
{
v3 = (*v1 + ...
0
votes
0answers
44 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 ...
1
vote
2answers
140 views
High-level langage decompiler on WIndows
So I have been using Binary ninja and I was wondering if there was any other tool except IDA or any binary ninja plugin that would transform assembly code into high level code, I already tried binja-...
1
vote
0answers
100 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
...
0
votes
3answers
148 views
I'm looking for a list of C vulnerabilities like OWASP Top 10
I'm looking for a list of all vulnerabilities that can be present in C so I can practice them all.
I found this: Category:C/C++, but it's not of much use.
0
votes
0answers
61 views
How to detect the language of an assembly code? How radare does it?
I've opened an executable in Radare2 (on Cutter) and it says that it was written in C language. Is it just a guess or there is a good way to find in which language a binary was written?
1
vote
1answer
66 views
Is there a handy assembly to mock app conversion tool?
It might be too silly of a question, but here you go.
Suppose you have some software that contains a tricky nested assembly sequence (like this one) you try to reverse engineer. brain*[pen&paper] ...
1
vote
1answer
59 views
How to create an executable that keeps the same virtual address on different runs
I want to create an executable that keeps the same virtual address during different execution runs.
This is definitely possible because I've seen these files in CTFs(Capture the flag) where the ...
1
vote
2answers
109 views
Detecting and solutions of stack smash protection
This video https://youtube.com/watch?v=4HxUmbOcN6Y presents how modern compilers protect stack overflows with stack cookies and function __stack_chk_fail.
How can one identify if a binary has stack ...
1
vote
2answers
255 views
Methods for preventing IDA decompiler
I want to write a C function, such that hex-rays decompiler will fail on it. I want to do it for study purposes, and not for an actual anti-reversing method. Do you have any recommendations/approaches ...
1
vote
2answers
128 views
How to solve this anti-disassembler trick?
I have this __asm instruction in C code:
int func_0x8b4c55a0()
{
__asm
{
call $ +5
add[esp],5
ret
}
}
int main()
{
char cVar1;
if ((cVar1 = ...
2
votes
1answer
3k views
Best way to protect source code of .exe program running on Python?
I am developing proprietary software that would be distributed in a form of .exe file. In order to use it, users will have to authenticate with their whitelist credentials (username + password).
The ...
0
votes
1answer
83 views
Abusing the strlen output
My question is related to the strlen function from the C and C++.
I am reversing a program, that reads a byte data from allocated memory and sends to the strlen directly. To be completely honest ...
1
vote
1answer
332 views
Why is fastcall used for replacing thiscall functions in memory instead of cdecl?
Assume I were to be reversing some game which processes all of it's movement client side and have determined some function to be of the type:
bool __thiscall Player::CanJump(Player *this)
that I ...
1
vote
1answer
158 views
mfc140 dll , what is the usage?
While I open exe file in ida I can see lot of calls to mfc140_6153
or mfc140_8718.
What are those functions ? what they do ?
thanks
0
votes
1answer
132 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 ...
2
votes
1answer
146 views
Unable to properly analyze a very simple C-compiled program
I'm a RE beginner and I decided to start writing my own simple code for practice.
I wrote a simple code which uses a winAPI function called CreateProcess to start a calc.exe, I've wrote it in C and ...
1
vote
2answers
1k views
Local variables and addition not shown in Ghidra
I am having some troubles with my learning of Assembly and reverse engineering. Specifically, I am learning about Global vs Local variables. For Global variables I have managed to get insights in ...
4
votes
1answer
2k views
Simple C program disassembled with Ghidra
I am trying to figure out what is going on with my simple example programs, when I disassemble them with Ghidra. I am not sure whether this is some strange Ghidra behaviour or something that is set by ...
-1
votes
1answer
194 views
What is the following assembly code doing? [closed]
str fp,[sp, -4]!
add fp, sp, #0
sub sp, sp, #12
str r0, [fp, #-8]
str r1 [fp, #-12]
L5:
ldr r3, [fp, #-8]
ldrb r3, [r3]
cmp r3, #0
beq .L2
ldr r3, [fp, #-12]
ldrb r3, [r3]
cmp r3, #0
beq .L2
ldr r3, [...
0
votes
1answer
377 views
Can we hook the Nt or Zw functions using IAT hooking, or just inline hooking?
So i was trying to hook the ZwQuerySystemInformation or NtZwQuerySystemInformation using IAT, but i found out that these are not inside the IAT inside the memory nor in the PE file
but maybe i am not ...
-1
votes
1answer
130 views
Understanding (pseudo-)C function from a video game [closed]
I recently found a function using IDA within a game that creates a CRC from a string. I don't understand much of the code or how the game takes in the string as data.
__int64 __fastcall ITF::...
2
votes
3answers
551 views
Elf x86_64 adding function
I'm trying to see if I can append function code in the .text section of an ELF while still maintaining the execution flow of the original ELF. Ideally, I want to call the new function but that's it's ...
0
votes
2answers
159 views
Unable to exploit format string vulenrability on Ubuntu 18.04.2 LTS
I am studying from "Hacking: The Art of Exploitation" and in program fmt_vuln.c format string is exploited. I am getting Segmentation Fault error.
Checking position of AAAA on stack:
$ ./fmt_vuln ...
