Questions tagged [gdb]

A source level debugger based on `ptrace` for *NIX systems and developed by the GNU project.

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40 views

Debug shared library in Android application

There is an Android application that has a shared library (.so) file in split_config.arm64_v8a.apk that I want to debug . When I look at /proc/PID/maps I don't see that library (I do see the ...
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1answer
22 views

Adding ltrace information to gdb

I'd like to run gdb (or gdb-peda) with ltrace like info on each syscall. How can I do that? I know that, as per ltrace and gdb attach to same process , you can't actually attach ltrace and gdb to the ...
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1answer
44 views

How can I find out the size of heap allocations?

While I debug with GDB I see the address of a buffer that's located on the heap. How can I know what is the size of this buffer? Or where (in the code) this buffer was originally allocated? When I ...
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1answer
96 views

Connect remotely with GDBSERVER to pid

When I run gdbserver to listen for port and connect remotely with gdb: Gdbserver command: gdbserver --multi 0.0.0.0:4444 Gdb command: target remote 192.168.1.99 4444 In gdb . How can I connect to pid ...
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48 views

Passing a String into a Function With GDB

So, I have a function with the prototype according to GDB: {std::string (std::string)} 0x56027729e545 <function(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator&...
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1answer
66 views

PEDA: Don't show context

gdb-peda shows a very useful context each time it stops (b, si, etc.), but sometimes I don't want it. Is there any way to quiet it so it won't show the context automatically (unless prompted context)?...
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42 views

Remote debugging with Binary Ninja on Windows possible?

Quick background -- I cannot start the .exe from a debugger; I need to attach after the fact. Binary Ninja's debugging plugin only allows attaching to a remote debug server and not a process. The ...
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1answer
42 views

Paint path in Ida according to gdb log file

In Gdb I put script that print each instruction to gdb.txt file. I want to load this file to Ida to show and print/paint the path that the process has been running. The gdb script is # not strictly ...
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35 views

Handle Ioctl call while running with qemu

I am using qemu to emulate a binary like this qemu -strace XXXXX . I saw that the first 2 system calls of this process were TCGETS to stdin and stdout. From man pages Get and set terminal attributes ...
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1answer
59 views

Debug bFLT in qemu-arm-static

I have bFLT binary (into linux-arm arch.) that I can run with qemu-arm-static . I want to debug that binary dynamically with GDB. I know I can debug binary with qemu like qemu-arm-static -g 1111 <...
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408 views

How to decompile python ELF file (Compiled with Nuitka)?

I have some files that compiled with nuitka. formats are .bin. I could get shell access to running process with pyrasite same as this guide. but I cannot decompile function codes or anything else, and ...
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1answer
645 views

startup program exits with code 126 when executing program at entrypoint

I want to reverse engineer a program. I managed to find the entry point but every time I want to launch the application I get the same error `During startup program exited with code 126. Here is what ...
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58 views

/bin/sh shell not execute when performing ret2libc attack

I have attempted to do a ret2libc attack. It's a simple buffer overflow with the return address pointed to the system call with the string "/bin/sh" on the stack. For some reason, when I try ...
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2answers
85 views

Changing value of parameter with gdb

I have a file named exploit.c inside which: #include <stdbool.h> #include <stdio.h> const char y1 = 'a'; const char y2 = 'b'; const char y3 = 'x'; const char y4 = 'y'; const char y5 = 'i';...
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1answer
60 views

Confused about the use of the shl instruction in this disassembly

I created a code construct in C to see how it looks in x86. I'm confused about the use of the shl instructions. I'm confused about what is happening in between the lines <+39> and <+51> I ...
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0answers
177 views

How to perform full MIPS system emulation with QEMU, using the squashfs image and uBoot kernel image?

TL;DR: Need tips on emulation of MIPS-BE system using QEMU with the help of squashfs image file and uBoot Kernel image file extracted from the firmware file. Long Version: - What I have: A cheap ...
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2answers
77 views

I'm confused about parameter in Printf function

I'm trying to understand call conventions and such. I created a function with the source code #include <stdio.h> int main() { int x = 9; printf("%d\n", x); } The above screenshot ...
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1answer
150 views

GDB inserting breakpoint cause Segmentation Fault

I was trying to play around with gdb, and I'm especially interest in seeing how the Procedural Linkage Table(PLT) and the Global Offset Table (GOT) interact with each other. So I set some breakpoints ...
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91 views

Using GDB to find the address of a buffer in a stripped C binary

I am working with a crackmes binary called Simple Overflow. It has two buffers with sizes 0x10 and 0x8, and it uses malloc to allocate two contiguous memory blocks (see <+25> and <+39> on ...
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2answers
95 views

How can i recognize the length of this array based on the assembly instruction?

In the sourcecode i can clearly see that the Array called "buf" is 32 byte long since 1 char = 1 byte I assume that the array starts at the address [rbp-0x30] and the argv[ ] is stored in ...
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1answer
92 views

Set gdb breakpoint by address with gdb python

into GDB python I tried gdb.Breakpoint('0xaaaa') I got error Function 0xaaaa is not defided . Breakpoint 5(0xaaaa) pending and the program not break at this address. Why is that?
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173 views

Print write and comment into .gdbinit file

Is there any way how to write comment into gdb file? b*0x1111 # break point at function or b*0x1111 // break point at function or b*0x1111 ; break point at function That return an error . Or maybe is ...
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1answer
39 views

Define operations to do in specific breakpoints using GDB

In gdbinit I defined some breakpoints. How can I do that when specific breakpoint called I want to run x/s $r1 ?
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1answer
330 views

How to let SIGTRAP get caught by sighandler in GDB?

I have a program that I am trying to reverse, which contains an int3 (0xCC) which emits a SIGTRAP signal, which is then handled by a sighandler defined in sigaction. The handler performs calculations ...
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1answer
464 views

Attach to process with gdbserver without stop it

I run gdbserver gdbserver --attach :<port> <pid> and then connect with gdb-multiarch The problem is that until I connect with gdb-multiarch and run c the process is stop. Can I continue ...
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What do you think is the optimum environment for reverse engineering dynamically-linked aarch64 Golang binaries developed in Alpine Linux?

Direct quote from Golang's website: "GDB does not understand Go programs well. The stack management, threading, and runtime contain aspects that differ enough from the execution model GDB expects ...
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1answer
856 views

Correct way to understand local_ in ghidra disassembly

Attached is the part of a disassembled main from a x86 binary file, generated by ghidra. ************************************************************** ...
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345 views

Remote Debugging an Aarch64 ELF File on Multiarch/Qemu-user-static (arm64v8/alpine) Docker Container

My goal is stated in the title. However, I think there is a fundamental issue with gdbserver. In particular, I create an aarch64 alpine docker container on a x86_64 Ubuntu 16.04 host using sudo docker ...
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1answer
434 views

ELF binary injection

I am currently working on an ELF-injector and my approach is standard: find code cave (long enough sequence of 0's), rewrite it with the instructions I want to execute and then jump back to the start ...
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1answer
123 views

Edit IDA signal handler

In Ida Pro while debugging linux process with gdbserver I got window that show than SIGTRAP has been arrived, I choose to pass it to application. How can I edit that choose now? I want to ignore this ...
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0answers
94 views

Dynamic Analysis with gdb on ELF binaries with no compilation/linking information

I am trying to do some dynamic analysis on a couple of ELF binaries with gdb. However, since those two are directly downloaded (ELF binary file only) with no additional information related to ...
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1answer
726 views

How to watch a function's local variable in GDB?

I'm reversing a 64bit binary with gdb & peda and I've identified a function of interest (probably encoding user input). I want to watch the function interesting's local variable arg1. How can I ...
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64 views

ret2libc exploit issue

i have some code in c i am working to write exploit for it: #include <stdio.h> void secretFunction() { printf("Congratulations!\n"); printf("You have ...
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1answer
124 views

Setting Breakpoints on Thumb Instructions in GDB

I'm practicing reversing a stripped arm binary, and found that when I set a breakpoint at say 0x010451, and run the program, gdb spins forever until I hit ctrl+c. When I do, the current pc is at the ...
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1answer
262 views

GDBserver on Qemu not honoring "follow-fork-mode child"

I am using gdb-multiarch version 9.1 on Ubuntu to connect to a qemu-mipsel-static version 4.2.0 running a MIPS application which daemonizes itself with fork(), and which is running the built-in ...
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1answer
148 views

Is it possible to find a running process's arguments to main from an attached GDB?

Given a very basic program, perl -e'$|=1; print $$; sleep 500;' HELLO WORLD How can I find HELLO WORLD using GDB? I thought bt -full but when I attach and run, I get #0 __GI___clock_nanosleep (...
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1answer
68 views

Use dtrace, lldb or gdb to find which file or line of code was responsible for a line of output in stdout or stderr?

I see a string being output to my Terminal, when I ran an executable. I have the source code (in C) of the executable, but it was not written by me. I compiled it with -g flag. Is there any way to ...
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1answer
365 views

Can I force GDB breakpoints and disassemble?

Sorry English isn't my first language. I noticed something when setting breakpoints in GDB. It appears that they are ignored if symbols aren't loaded. I have found it weird how GDB behaves when there ...
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2answers
50 views

How to call to function while debug

When I debugging remote process with gdb-server and Ida, and put breakpoint in the code, when the process stopped at this breakpoint how can I call to function and after that return to my code ?
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1answer
412 views

How can I get my shellcode to work outside of GDB?

I'm working inside a Warzone VM with no ALSR or NX bit. The program I'm trying to exploit is really simple: #include <stdlib.h> #include <stdio.h> #include <string.h> /* * ...
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1answer
47 views

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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1answer
76 views

Debug process that use /dev/watchdog

I want to debug a process with gdb into Linux system, but the problem is that process pings /dev/watchdog so when I tried to debug it, it stop the process for longer than the watchdog interval so the ...
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2answers
82 views

Is address in program can change

I talking about linux arch. When I open program in Ida (statically ) I can see all instructions address like 0x20da mov r8 r2 When I want use that address to breakpoint (for example with ptrace or ...
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1answer
250 views

How to detect which shared libraries a binary is actually using?

I have a stripped-down Linux-based embedded system where a closed-source program(32-bit ELF binary for MIPS) depends on several shared libraries. Two of those libraries are actually the same libcurl ...
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1answer
46 views

GDB disassembly - breakpoint problem

My question is, when i dont use any breakpoint it show the message saying "You made it, now keygen me!", but when i put a breakpoint in the main, or any other place it will show a message about ...
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1answer
42 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 ...
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1answer
75 views

ASLR and it's effect

I was debugging some programs with gdb, I already set the disable-randomization to on, but I was having trouble, I set a break point and examined that the $sp is different everytime, what causes this ...
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1answer
561 views

GDB - Send Python output to the program after SIGINT

I am trying to learn GDB to better understand buffer overflows but I can't find an answer to my problem which is how can I send a Python-generated output to the program when the program asks for user ...
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1answer
112 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 ...
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1answer
350 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 ...

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