Questions tagged [gdb]

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

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Binary Exploitation

I am trying to learn binary exploitation. I can modify the binary behaviour with gdb, but I have not understood how to exploit the binary in C. I've found some references on "Hacking - the art of ...
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How to get the address of a glibc private symbol at runtime programmatically?

I am trying to get the address of a private function in GLIBC. For instance - the function __run_prefork_handlers(). I have done it with gdb, using info symbol __run_prefork_handlers and info address ...
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format-string + ret2libc (or format string only)?

I found that we have a format-string bug with in argument 7. I found a function containing system(/bin/sh)). So I'm not saying stupidity I have to mess with a format-string and a ret2libc (correct me ...
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IDA remote GDB debugger cannot suspend linux machine

I am starting Debugging Linux Virtual Machine by IDA GDB debugger. I can say I am able to connect to process (0) and start the machine (by using IDA 32bit, IMO it has something to do with bios! or I ...
2 votes
1 answer
85 views

GDB breakpoint crashes at a correct memory location

I'm trying to debug binaries of a a firmware running Linux with no ASLR, binaries are not compiled with PIE either so I have no issue getting the memory locations. So after including gdbserver in the ...
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debug stripped file

I've system embedded mips big endian with gdb-server and I want debug stripped file of the target, I can run in target gdb server with stripped file (--attach PID), but when I try to connect with gdb-...
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1 answer
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How can I verify section -> segment mapping for ELFs on linux?

I'm looking at at ELF on linux and I have readelf --segments ./myELF which shows: Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align PHDR ...
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Is there a way to reprint the screen in gdb gef?

I am using gdb-gef and I've searched the manual several times for the answer to this question. Sometimes I run a lot of commands and I would like to re-draw the current program state the way gef ...
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GDB "Cannot access memory at address ...." Breakpoint error

I have not yet found the solution on internet so i ask it here. Never had this problem before it was always doing fine, so i don't know what changed. I'm using gdb peda but the problem stays the same ...
1 vote
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can't debug properly

In the last few days I tried to solve "unlink" challenge in pwnable.kr and I'm struggling to attach a debugger remotely and locally on the server using pwntools (code added below). #!/usr/...
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4 votes
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What utilities allow you to debug a process without pausing execution?

I was just reading this answer on StackOverflow, "How can you debug a process using gdb without pausing it?" The Linux kernel provides some support for this via PTRACE_SEIZE, but gdb doesn'...
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1 answer
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Gdb hardware watchpoint error on android

After failing to find a solution to this I have started using Gdb and have encountered another error. Gdbfails to set hardware watchpoint when I'm remote debugging a rooted arm7-a target. It supports ...
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1 answer
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Debugging Windows applications on Linux: Hardware watchpoints and backtracing in IDA not working and winedbg hardware watchpoints borderline unusable?

As in the title. Maybe someone has any experience with this. It's a significant impediment when trying to debug Windows applications on Linux. I find hardware watchpoints, in particular, to be ...
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1 vote
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Why Qiling doesn't recognize the right EntryPoint?

I'm trying to emulate an EFI driver. Luckily, I found a nice emulator called Qiling and try to debug it with GDB but it doesn't recognize the right Entry-Point. Here is the Entry-Point in IDA and in ...
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1 answer
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ROP: System function not printing results to stdout

in oder to solve a CTF-Challenge I have to construct a small ROP-chain. The scope of the ROP chain is to print the content of the `flag` file. I already constructed the ROP-chain, but it seems that ...
1 vote
1 answer
122 views

breakpoint already hit 1 time

I'm following Erickson 2008 Hacking the art of exploitation. The program is very simple. #include <stdio.h> #include <string.h> int main() { char str_a[20]; strcpy(str_a, "Hello, ...
1 vote
2 answers
435 views

Run a python in command (kali) with "run" on gdb-peda$

While debugging a program under gdb with gdb-peda installed, I need to pass args to the binary using output from something like python. Why I am not getting AAAAA? gdb-peda$ b doSomthing gdb-peda$ run ...
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Print CMarkupSTL object with GDB

CMarkupSTL is contain XML. How can I print that XML with GDB while I debug process? I run on Arm Linux
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26 views

Using rbreak without import functions

While debugging with GDB I want to break for each function and print the PC register. rbreak . define hook-stop i r $PC c end The problem is that is stop on functions that imported like printf ...
2 votes
1 answer
868 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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1 vote
1 answer
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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 ...
1 vote
1 answer
746 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 ...
1 vote
1 answer
214 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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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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1 answer
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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)?...
1 vote
1 answer
59 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 ...
1 vote
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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 ...
1 vote
1 answer
127 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 <...
2 votes
0 answers
2k 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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2 votes
2 answers
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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 ...
0 votes
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138 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 ...
2 votes
2 answers
277 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';...
3 votes
1 answer
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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 ...
2 votes
0 answers
482 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 ...
1 vote
2 answers
193 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 ...
2 votes
1 answer
464 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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322 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 ...
2 votes
2 answers
194 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 ...
1 vote
1 answer
351 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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766 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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1 answer
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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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1 vote
1 answer
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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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1 answer
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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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4 votes
1 answer
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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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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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4 votes
1 answer
1k 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 ...
1 vote
1 answer
315 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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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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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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