Questions tagged [disassembly]

The translation of machine code into a human readable assembly code, also the result of such translation.

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Review a collection of executable binaries to determine similarity

I have a collection of different binaries I want to review for code similarity and classification, but I would rather not have to open each of them in IDA and manually review the code in 15 different ...
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Reverse engineer .so file from android app with radare2

I have a .so file from an android app, and I know how to list all functions in IDA Pro. How can I do this with radare2?
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69 views

Adding a static variable to Windows DLL

I'm trying to patch a function in a Windows x86 DLL, however it turned out that I need a static variable to store some state that wasn't correctly preserved by the original executable across calls. I ...
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44 views

Getting radare2 to load z80 binaries properly

I'm trying to disassemble some Sega Master System roms. In order to do so, I've checked for the extra 512 bytes from old roms and once I was sure they weren't there, I proceeded to run radare2 on one ...
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76 views

Shellcode not working correctly

I wrote a small program in assembly which is supposed to print "AAAA". It works fine when I run it directly, but when I run it as a shellcode in a c program, it doesn't work. Please help. Here is the ...
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131 views

Understanding ghidra disassembly

I'm kind of new to assembly and ghidra as a tool. I have a question about the meaning of this line Mov dword PTR [ESP] => local_70 , eax I get we are moving eax into the left side but I'm not ...
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Yara sigs based on imported functions used in code snippet

I'm looking to write a yara signature based on an interesting decoding algorithm in a family of malware, but I'm having difficulty with correlating addresses with imported functions. Specifically, I ...
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31 views

Help with IDA pro please — functions made are not Xref'ing to the caller

I am reversing some Motorola 9s12 (68hc12) code and using IDA pro. I am having the strangest issue. The code makes a call to a function: ROM:B300 call $BFF7, #$FE when I go to ...
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How to see assembly of main function?

How can I dump the assembly of main function of binary(not striped) in ubuntu? I want to see the assembly command and the hex value of this command There are 1 binary for arm and 1 binary for x86
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Can you add data to a binary, without affecting its jump labels?

I'm a total beginner, so I don't know the vocabulary yet to search effectively. What I want to do is add some data (let's say level data), to an old game ROM, but that would probably shift all the ...
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Disassembly - First steps

I decided that I need to understand this more thoroughly, so am working in parallel with two resources: one more modern and one original from @Aleph1. In the essay, there is a basic code snippet, ...
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43 views

Renaming variables radare2

I have a variable called var_14h in disassemble code. I want to rename this variable. I try to rename the variable by using the following afvn var_14h i However, radare complains and returns an ...
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Within A Folder of 100s of 16-bit MS-DOS Disassembled EXEs Identify Ones That Need/Use DOS/4GW

So far I batch disassembled all files using following PowerShell and IDA: $files = Get-Content S:\files.txt ForEach ($file in $files) { Write-Host "Processing $file" &"C:\Program Files\...
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91 views

Byte-patch a JMP

I have an address and I want to byte-patch it because there is a JMP that I want to block. But when I NOP it, the game just crash because it corrupt the function. So, I don't know what to do for block ...
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59 views

Executable code in the same location differs in memory and on disk

I'm trying to inject code to change the byte value of a CMP in an executable from 0 to 2 at runtime, in order to effectively no-op a boolean comparison as part of an effort to insert my own behavior. ...
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Linux encryption/luks/pymouth password scripts corruption

I noticed that the bootup scripts that collect the password for full disk encryption on linux (fedora-31) were displaying corrupted text. The kind that looked like binary data being printed at text: ...
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60 views

Strange function in Disassembly (IDA)

I was reversing one executable in IDA and found out the function with this structure: .text:0058A6E0 sub_58A6E0 proc near .text:0058A6E0 .text:0058A6E0 var_4 = dword ptr ...
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Find High Entropy VA (64-bit ALSR) Incompatibility in Disassembly

Have a 64-bit plugin DLL (no source code) and the host application in an update changed its DLL characteristic to include "high-entropy 64-bit address space layout randomization (ASLR)" When this is ...
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Why Ghidra doesn't load the disassembly correctly while radare2 does?

I'm trying to get the disassembly of a very small binary file available here. This file is cropped from part of another executable binary. When I open it with r2 it automatically recognizes the ...
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69 views

IDA Pro ignores condition in breakpoint

Look at the condition. It is supposed to break only when the R2 is 40, but it breaks in any call to this instruction. I'm using IDA Pro 7.2.181105, debugging with Remote GDB Debugger, an ARMv4T code. ...
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94 views

How to reverse engineering a proguarded .apk? [closed]

Lets say you have android1.apk file coded with proguard enable. I want to reverse engineer it in such a way that it shows the original methods names instead letters of alphabets, example bellow ...
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84 views

Ghidra can't Decompile kernelbase.dll exported functions?

I was trying to understand the IsDebuggerPresent() function exported by kernelbase.dll by importing the file on Ghidra. But Ghidra can't show me the proper disassembly or decompilation of function ...
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60 views

Why does this execve shellcode work with this argv?

I wrote the following program in fasm, and am using Evan's Debugger on Ubuntu to debug it: format ELF64 executable 3 segment readable executable entry $ mov rbp, rsp sub rsp, 32 mov rax, 'this a t' ...
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177 views

Static analysis obfuscated code

I'm reversing a code that is heavily obfuscated. It uses opaque predicates, call stack tampering, junk code and control flow flattering. Call stack tampering uses indirect branches (push register / ...
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reverse engineering hi3516ev200

I am new to reverse engineering and will describe my situation thus far. In short, I am looking for some tips on what to do next to gain access to a piece of hardware I am playing with. I bought a ...
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34 views

How to determine what code created a string, in a live debugger session?

I'm using IDA 7 to debug a running application that must be a child of another application, which means I can't start it from IDA (using Debugger->Run). Instead, I have to run the application normally,...
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54 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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2answers
39 views

Any “simple” way to disassemble a block of hex for a 80C188?

I have used IDA to disassemble a big EPROM (27020) but there remain a large number of code sections which haven't been disassembled. Here is a typical one where I have identified the beginning and ...
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Learning Intel Disassembler, What to learn for Intel XED [closed]

In order to learn about disassembly and code something like Capstone disassembler, HDE etc. for a function , calculate opcodes etc , Please advise on what I should know. I have some knowledge of ...
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80188 relocation register mystery

I'm reverse engineering an embedded system using the 80C188 and the way the relocation register (RELREG) is used mystifies me. One of the first steps at initialization is to move the processor ...
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39 views

submitting input into AFL fuzzer

I have some questions about the AFL Fuzzer: How does the AFL Fuzzer know where to inject the payload in the code I compile? For instance if I want to inject it in a specific parameter, how do I do it?...
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114 views

Is it possible to use a program's GUI abilities without the GUI?

Is it possible to use/call programs' GUI abilities directly without using the GUI (programmatically, not by keyboarding)? For example, a program with abilities nested too deeply in cascading submenus:...
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How to recover randomly generated private key from a Program that implements Diffie Hellman Exchange

This program implements Diffie Hellman key Exchange, a pair of random private keys are generated every time the program runs. How should I go about finding the random number generation subroutine ...
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34 views

IDA Fails to Analyze Stack Pointer Correctly in Heavily Chunked Functions

I am currently dealing with obfuscated code in IDA. The obfuscation I am combating is control flow obfuscation, where a function is split up into hundreds of basic blocks spread across the entire ...
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reflection in objectiveC - method invocation return null value

I'm trying to reverse the way dpsconfigad extracting the current active directory domain. Notice : It's rather simple query that can be performed using OpenDirectory public framework but it requires ...
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68 views

How can I objdump the assembler code of dynamically linked functions in a dynamically linked executable?

Compiling a minimal C++ program: g++ -g -Wall -Wextra -std=c++17 -o prog main.cpp int main() { } Performing an objdump -C -D prog of all sections I am given the following output: prog: file ...
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Setting struct according to offset relative to struct base

I would like to know whether it's possible to define a struct according to offsets from base in Hopper. Assuming there is a register in the assembly code, that I believe it represent the instance ...
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50 views

TMS320VC5416 DSP firmware reversing

I have file with DSP firmware inside. Each chunk of code or data is preceded by header with format "page,offset,length".See below full list of headers: page: 0000 offset: 0080 len: 0149 page: 0000 ...
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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 ...
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199 views

Strange vtable setup in constructor disassembly

In a program I'm trying to recover data structures I've discovered the following strange (ARM) disassembly code: ctor_1: ldr r1, =vtable_base str r1, [r0] ;r0 always contains ...
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117 views

How to use memory address information from IDAFree to set a breakpoint in x32dbg?

I have a DLL paused at EntryPoint in x32dbg. I am interested in examining memory following a specific API call that this DLL makes. I found the API call in the imports section when I open the DLL in ...
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124 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 ...
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Radare2 8051 code bank switching

Some of 8051 chips use bank switching to extend accessible code memory. Good example is Silabs C8051F12x. Another example is here. Code area in range 0x0000..0x7ffff is common always accessible code ...
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Radare2 jump/switch table walk for 8051

For 8051 target exist famous no-return function with body of d083d082f8e4937012740193700da3a393f8740193f5828883e4737402936860efa3a3a380df which correspond to ?C?CCASE function: / 38: fcn.00000000 ...
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Is it possible to define the adress of a function in assembly?

I am creating a PoC for anti-disassembly techniques, and I would like to know if there were ways to define the address of functions once compiled with gcc. Here is the PoC program : BITS 32 EXTERN ...
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90 views

Entry point of a program

im new to assembly and reverse engineering, i have a question regarding to how the address work. I examined the entry point of a program using varies PE tools, the result is 0x00043b33, but when i ...
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What is the difference between malware that is 'dumped' and one that is 'unpacked'?

On malware sharing communities, I have been noticing that the samples shared are marked as unpacked or dumped. I have tried to load the dumped malware in IDAFree, however, there is nothing in the ...
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210 views

Python Script to get disassembled output of an EXE file

I'm pretty new to Ghidra, and looking to use it's API (headless analyzer) and get the assembled file through command line using python. Here is my code, which is likely far from the correct code. It ...
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How can I navigate to the Disassembly address location?

I'm using x32dbg and I've set a hardware memory breakpoint. It triggers successfully for a specified module and the debugger pauses and a message on the bottom says: Hardware breakpoint (byte, read/...
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155 views

Where is the ESP after call instruction?

I've started learning the Reverse Engineering and when I read the Stack Operations and function invocation, there are an issue that I'm confused. -What is the address of ESP after "pop ebp" and "retn" ...

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