Questions tagged [elf]

the Executable and Linkable Format is the main executable and object format for Linux, Solaris, *BSD, and many other OSes...

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Statically injecting translated NASM assembly into existing ELF binary

I'm trying to statically patching ELF binaries in order to incorporate code that can help provide run-time protection. In an effort to save time writing and debugging assembly, I took the following no-...
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What are some significant similarities and differences ELF format has with PE format?

I've learned extensively about PE and PE64 format a while back. I am now digging deeper into ELF format. However, I've not found as many thorough resources for ELF as I did for PE, such as ARTeam's PE ...
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Is there a way to debug an elf file that runs with no problems with damaged header?

My question is general, but to have an example to work with, let us take one from Whirlwind Tutorial. ; tiny.asm BITS 32 org 0x00010000 db 0x7F, "ELF" ; ...
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How are members of a Structure Type positioned on the stack?

Some of the structure types have members that are not stacked next to each other. Check out the structure type at 0x33E6 in bzip2_base (x86-64) here. There's an int at location offset 0, a char at 4 ...
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How is padding size calculated for members of structure types?

Looking at DWARFs of bzip2_base I see different offsets between members of a structure type although they are of the same type. Check _IO_FILE structure at the offset 0x9c here. All the way until the ...
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GDB exited when running library

I'm new with gdb and I have spent hours looking for direction but I can't find any. I need to analyze an executable to find how this program process the arguments and where the output came from. I ...
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Extracting strings from Go binaries

Is there an easy way to extract all of the strings from Go binaries that will work cross architecture? The problem with Go is that strings are stored without a null terminator so you can't use the "...
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What is PLT/GOT?

From time to time, when disassembling x86 binaries, I stumble on reference to PLT and GOT, especially when calling procedures from a dynamic library. For example, when running a program in gdb: (gdb)...
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What is actually loaded here and different hexdump outputs on util-linux hexdump and on cutter and ghidra's hexdump

I was trying to understand what segment of file gets loaded by fourth LOAD header on phdr array. First 6 headers are shown below from readelf Program Headers: Type Offset ...
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Combine two ELF binaries

Without having access to the original source code, is there a way to combine two ELF binaries with the main() in the first binary pointing to the main() in the second binary ? In other words, I mean ...
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459 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 ...
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Edit an .so file

I have here an .so file that contains a language pack and I want to edit them. My problem is that I don't always have enough space for a clean translation. I know that I can change the texts if they ...
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dwarf: variable offset from base

I have a simple code: int main() { int a = 4; printf("%d\n", a); a = 8; if (a == 8) printf("%d\n", a); return 0; } DIEs for the function and variable: <1><32a>: Abbrev ...
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How to force IDA to properly parse the ELF header?

Is possible to force IDA to parse the elf file into its appropriate fields without resorting to IDC/IDApython, I mean is there a built-in functionality that I'm missing? For instance it possible to ...
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322 views

Disassembling Hexagon - Corrupted ELF

I downloaded and unpacked the modem from Google source, after that I used laginimaineb's script to unify all modem binary data. However, when loading this binary to IDA, I get an error says: "Binary ...
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Shellcode execution segfault

I have been trying to exploit simple buffer overflow caused by scanf. I'm working on x86 Linux. The point is to spawn a shell. I sucesfully overwritten return address and jumped into my shellcode. But ...
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4k views

How to export a working elf binary from Ghidra?

When patching a program and then using the export binary function, it turns the elf headers are corrupt. Is there any way to work around this problem?
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“check:” keyword in Ghidra

I have disassembled the crackme0x06 challenge (http://security.cs.rpi.edu/courses/binexp-spring2015 inside challenges.zip). It's an ELF 32bit unstripped binary. The decompiled C code using Ghidra ...
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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 ...
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Reassembling ELF binary files

I have been doing a number of CTF activities when I came across something I’m unfamiliar with. As I am somewhat new to exploitation and reverse engineering, this was unfamiliar to me. I have 7 pieces ...
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CHBByteStream operator<<, get only one argument - value

Anyone heard about CHBByteStream? It's from Harman headunit (car radio). I don't know how it's passing arguments. SWID is 4 bytes, VIN is 17 bytes, it should be connected in some way, to pass thru ...
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Ghidra python - get program base address

What is the way to get the program base address in Ghidra?
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Dumping the GOT with gdb at run time

I want to see how the plt stubs are being resolved at run time when lazy linking is used and how the GOT is changed along the way. How can I dump the GOT with gdb?
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Conditional to check bytes against user input [ELF 32-bit]

I'm trying to understand the following snippet code from a CTF binary. It is part of an ELF 32-bit and I decompiled it with Ghidra. undefined4 check_serial(char *code) { size_t sVar1; undefined4 ...
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Can “missing section headers” ELF files still be executed/dangerous?

On VirusTotal, there are lots of ELF samples are missing section headers when using file command to see the info. Also, when using the Python elftools library to parse them, exceptions will be thrown....
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GCC is not recognizing symbol table in my hand-made ELF file

For learning purposes I've created (using a hex editor and some macros) the following ELF file: hello.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped xxd hello.o: 00000000: ...
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How to generate the call graph of a binary file?

I have a non-stripped ELF binary for which I want to create a call graph as a dot file. Is there such a tool which generates the call graph? EDIT: Is there away in addition to the conventional call ...
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Set a breakpoint on GDB entry point for stripped PIE binaries without disabling ASLR

Given a position-independent, statically-linked, stripped binary, there does not appear to be a way in GDB to set a breakpoint at the entry point without disabling ASLR. break start and similar ...
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118 views

ELF imported symbols colision

From what I understand, the ELF format doesn't specify which symbols come from which file - Every ELF that uses import has a list of symbols to import and list of file names, and the loader is trying ...
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ELF file crashing after executing shellcode

So after changing the entry point via the e_entry field I managed to execute my shellcode before returning control to the original entry point. Here's how I did it: // write string and jump to OEP, ...
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Cross debugging for ARM / MIPS ELF with QEMU/toolchain

as i'm new about cross-debugging and cross-compilation i need some help because i feel so confused. I have a MIPS elf file, [myelf][1] .You can see bellow the output of file myelf: myelf: ELF 32-bit ...
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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 ...
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problem rewriting ELF binary to add an additional loadable segment

I have a problem rewriting ELF binary to add an additional loadable segment for add.c code. I have problem working with https://pdfhost.io/v/U@uP1+nCY_Compact_Control_Flow_Integerity_in_Linuxpdf.pdf ...
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491 views

Radare2 create section

Radare2 has S* commands, that can show, delete, modify sections. Is it possible to create new section in executable file and save it?
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Importance of learning file structures for reverse engineering?

I'm new to reverse engineering and I have started to study the anatomy of specific file formats, specifically PE right now. I really enjoy learning the different parts of the files and the different ...
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How to locate module_init() offset from ELF header of Linux kernel module?

The header is self explanatory but to explain myself better. I have an ELF binary - loadable kernel module, compiled with symbols. I want to know how to locate the offset of the module_init() function....
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114 views

Convert PIE ELF binary into No-PIE

Is it possible changing few bytes for converting an elf binary from PIE to No-PIE (ELF)? I know that in the header if e_type is: - 3 then the program is PIE - 2 then the program is No-PIE So I ...
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How can I get the byte size of an operand in IDA Pro?

I am trying to get the byte size of all operands in a given instruction from IDA Pro. At first I tried using GetOperandValue(ea,n) to see how large the value was and calculate how many bytes were ...
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269 views

Unknown Game Client Data

As asking a friend and no amount of Googling yielded an answer, I figured I'd make an account and give this place a go. I'm working on reverse engineering the server for a relatively old game with no ...
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Struct reconstruction in decompilers

I'm testing several decompilers about struct reconstruction, given the following C example: struct S { int x; int y; long z; long t; }; int foo(struct S s) { return s.x + s.y + s....
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Find function in a stripped dynamic ELF library

Im currently reverse engineering an android app and this app calls a function named "getUserInfo" in an ARM 32bit ELF library called "libcms.so" (from TikTok) via the Java Native Interface. My ...
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ELF file format find shared object for symbol

(in Windows) PE file format contains Import table with Module\Dll Name which tells PE loader where to search for symbol e.g. KERNEL32.dll -> CreateFileW In the ELF file format there is Symbol ...
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114 views

How to use x64-86 elf file from an apk file in a linux machine?

I'm building a jar file that use jni to load an x86-64 elf extracted from Android apk file. But when I run my app, it throw this exception: Caused by: java.lang.UnsatisfiedLinkError: /lib/x86_64-...
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Why is IDA showing three arguments for the main function instead of two in some linux binaries?

So I am reversing an ELF‌ binary, now from my knowledge in C the main function has two argument, argc and argv but some linux binaries that i am reversing have 3 when i decompile them! one int and ...
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IAT vs GOT address resolving: which of them resolve during runtime and which during load time by default?

So based on my knowledge on windows apps, as far as i know the IAT gets filled with correct addresses when the library gets loaded (correct me if I'm wrong) now in linux, they use GOT, and again ...
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96 views

How to determine when/where pointers in .ctors get mapped?

So I am learning about ELF, and am looking through a binary in Ghidra as I do. I've made sense of the ELF header, and now I am looking through the program header table. My binary has a bunch of ...
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7k views

Making changes in ELF file after dissassembly [duplicate]

I am new to reverse engineering and after some research, I haven't found a clear way to do what I want to do. I have an ELF file, but not the original source code that generated it. It is really ...
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Enumerating (name, addresses) in PLT of an ELF file without elf.h

I want to show users imported symbols of a given ELF file like this(#1) in a disassembler project.(Android app) 1d21a: f7fa e8e8 blx 173ec ; __android_log_print@plt ... Currently, I can only show ...
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How to SUCCESSFULLY add a code section to an executable file in Linux?

I am in Linux, and I have seen this question a few times but never, nobody answered how to really make this work. I need to add a section to an already compiled binary. Lets say for a moment is an ...
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Packers/Protectors for Linux

I was wondering if anyone had come across a packer/protector which could be used for ELF binaries. There seem to be quite a few articles on writing packers and protectors for the PE format -- however, ...