Questions tagged [linux]

A free and open source POSIX compatible operating system with a monolithic kernel and a kernel module system. Originally created by Linus Torvalds.

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20 views

setting an initial value for a bss variable in elf

With the following minimal example code #include <stdlib.h> #include <stdio.h> int zero = 0; int one = 1; int two = 2; void main(int argc, char *argv[]) { if(argc > 1) zero = ...
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How to give multiple inputs to IDA when using remote linux debugger every time the program is restarted?

So this is a problem I'm facing when solving pwn CTF challenges i usually need to give many inputs for a program to reach certain point every time i restart it i tried to do it like this, by putting ...
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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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Interest in adapting signal processing for reverse engineering principally from a biogenomic standpoint [migrated]

NB: This was also posted over on dsp.stackexchange.com. I am seeking any possible help for a problem I have devoted a quite protracted period of time exploring. I am total perm disabled, and thus ...
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Endoscope Camera YPC99 - how to stream on linux

I'm trying to stream video from endoscope camera YPC99 on linux PC using the WiFi connection. From what I have found so far the camera is using IP 192.168.1.1. It supports RTSP protocol on port 7070 (...
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Repacking an embedded initramfs

I'd like to modify some of the init scripts in an initramfs that is embedded in a kernel bzImage. I know I can modify them by not changing the size of any files (e.g. by commenting out lines, and ...
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Open all object files in Ida

I have archive file , like libc.a . When I tried to open it with ida, ida ask to choose one object file that contain in archive file. Is there any way to open all the object files in one Ida project?...
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29 views

Find all syscall in statically Arm Binary

What is the easy and fast way to find all syscall in statically Arm binary ? Is there any Ida plugin that do that?
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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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Modern methods of fuzzing/locating heap bugs and potential vulnerabilites

really glad I found this great learning resource. I was wondering, is there any way to fuzz or automate heap vulnerability assesment? I know a lot of practical frameworks for stack based fuzzing in ...
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Find common functions in arm static binary

According to Detecting libc function with IDA I have static binary for arm and I want to find common function like fread sleep printf ioctl etc. When I looking for string in this binary I found glibc ...
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a.out: Invalid ELF image for this architecture

I am trying to run arm executable using qemu and I am getting this following error a.out: Invalid ELF image for this architecture. My assemble code hello.s .text .global _start _start: mov r0, #1 ...
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Modifying a legacy uImage

I have an old device from which I extracted a uImage. I know it has a linux kernel and a cpio filesystem in the uImage, and I need to make some changes to the filesystem. I'm hoping someone can help ...
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Format of Alcatel_Lucent I-240W-A backup file

I am trying to modify the backup file of this router in order to change some configurations. Here is the structure I have until now: 16 bytes of the header, zlib compressed xml with the ...
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Address of calling syscall

With strace I can see all syscall that process call. Is there any way to know witch address of process call to this syscall?
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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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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 ...
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Protected shell in embedded linux

When I run telnetd -l /bin/sh on an embedded Linux device and use Putty to telnet to it, the provided shell is /bin/psh (protected shell). On this device, /bin/sh is a symbolic link to /bin/busybox. ...
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IDA shows MEMORY or unknown references on C std library calls (memset, memcpy, etc.)

I'm currently reversing a Linux 32-bit executable (with a statically linked library included in it) but I'm having a little problem I can't find a solution for. Basically whenever I stumble across a ...
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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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The buffer is too short to insert addresses when exploiting buffer overflow

Newbie here. Sorry for what you about to read . I'm currently working on exploiting a binary on Ubuntu 18.04. Here is some information about the binary: Its checksec information using pwntools: ...
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ildasm on Linux: “original” ildasm.exe same as dotnet-ildasm?

I would like to use ildasm on Linux. The original one, that comes with the .NET SDK and can be found on Windows e.g. at c:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools\. I ...
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Extract files of a SquashFS Filesystem

I already asked a similar question but after a deeper analysis of the filesystem I found out that I misunderstood the problem and that's why I decided to delete the old question and make a new one. I ...
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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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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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Capturing traffic of an integrated laptop keyboard

I'm trying to capture the traffic between my laptop's integrated keyboard and its controlling software on Windows. I'll analyze the traffic to write a driver for Linux to control keyboard backlight. I ...
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How to input ascii control character into program?

I am working on a CTF where I need to pass an address as input to a program. This address contains the value 0x09 (the tab character). This is causing me problems, because it seems that bash is ...
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117 views

`qemu-mips-static` chroot causing `Invalid ELF image` error

I'm trying to emulate a MIPS binary on my Ubuntu 16.04 x86 system, but I'm not able to. I chroot into the squashfs-root filesystem that I got from binwalking the firmware image. kan3k1@kaido:~/...
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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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158 views

Prevent Memory Inspection in a Cython program?

Cython is a great way to protect the source code of a Python program. However, memory inspection and memory reverse engineering can still be done to this Cython program. What are ways to prevent (or ...
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1answer
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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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1answer
96 views

Unknown archive format from QNX operating system

We are reverse engineering a QNX system and we have found a small file that is uploaded to the system. It appears to be either a file system image or an uncompressed archive of some sort. We can't ...
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1answer
174 views

Reverse getline(cin, text)

I'm trying to solve a crackme that was made in C++, and I was able to "recreate" a function call, through the library calls the program made. Here's the piece of code that I'm trying to reverse: ...
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Extracting firmware image from binary

I have firmware file in .bin format, but I need get firmware.img image file and Kernel uImage file for reflashing bricked device. How can I get these parts? I used Binwalk to extract content, ...
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1answer
264 views

Radare2 ptrace can not attach

First my setup: Linux Mint 64bit 4.15.0-20-generic radare2 the newest version from github /etc/sysctl.d/10-ptrace.conf = 0 Executable: ELF 64-bit LSB executable, x86-64 read write and ...
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1answer
649 views

how to flash image.bin with uboot using serial or tftp

Hello I have a 4G LTE router which is blocked. and I have already dumped the partitions before via telnet from another device of the same model. U-Boot 2010.09 (Sep 06 2016 - 10:08:39)GCT GDM7243 ...
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1answer
480 views

How to do debug a running java process in linux?

TLDR I want to do live debugging of a java program on a linux machine, and don't how/what debugger to attach to the JVM to get this done. I expect that this is a well-solved problem, but I lack the ...
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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 ...
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Bufferoverflow Stack

I want to do a buffer overflow exploit in the stack. For this i read in data via the "gets"-function. void ExploitMe() { char buffer[256]; gets(buffer); } I compile this file with gcc test.c -...
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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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194 views

Why have two symbols tables?

Why have two symbol tables if .symtab already contains everything that's in .dynsym ?
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535 views

How can I pass input to my program while debugging it with IDA

I have a program that waits for the user to enter a string input, how can I enter that string input while debugging my program with IDA?
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539 views

Can i trap SIGSEGV (on a linux) and what are are the conditions to make it works ? (for a crackme)

Friendly greetings ! I'm writing some crackmes.one challenge and i want to write a challenge where the solution appears on a segmentation fault. (And you have to disassemble the code to find a way ...
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259 views

Unexpected SEGFAULT when there's apparently nothing that would cause it

This is a from a CTF problem I'm working on. Hopefully it's appropriate to ask this question here. Above is the GDB output when the segfault goes off. movaps is the offending instruction, meaning ...
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138 views

Understand what Ioctl do

I looking in ida on arm linux binary . I can see there that there is ioctl call ioctl(fd,req,num). fd is fd to /dev/module. ,req is some 4bytes and num is some number. How can I understand what ...
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375 views

Changing entry-point of and ELF file

I'm trying to conduct a little experiment which basically consists of changing the EP of an ELF file and executing an exit(9) syscall, without returning to the OEP. As shown in the image everything ...
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1answer
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Find out if address store in heap or stack

While dynamic debugging with ida and gdb-server on binary file running on linux , I saw address that store some value. How can I know if this address allocated in stack or in heap?
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145 views

Sniffing TCP packets using Wireshark

I am trying to reverse engineer a decoder. The decoder contains a web server that makes sending/receiving information through the Internet possible. To do so I need to sniff the packets that the ...
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IDA remote debugging - non printable characters in parameters

I am trying to remote debug a certain binary which gets user-specified command line arguments, which can be non-printable of course. My goal is the ability to debug with IDA the process with the ...
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1answer
326 views

Help needed to extract u-boot kernel & rootfs - nxp lpc 3143 processor

I have a board where in principle aim at emulating a DVD-ROM loading iso file from a drive. This board is running a ARM CPU with 32MB of ram and has no vga output. The firmware update comes with 2 ...

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