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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1answer
224 views

Changing local variable in caller from callee in C?

I'm implementing a function which is going to perform some time-consuming task, and I'd like to hack the benchmarking part a bit by changing the variable indicating the CPU time my function has ...
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1answer
120 views

ASLR in Linux Vs Windows

I am quite new in binary exploitation. I am doing a lot of beginners exercise here. I am confused about ASLR. I tried some binary exploitation thing in Linux. It was recommended that I should stop ...
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1answer
28 views

Create Fake Entry in sysfs

I'm targeting a program that tries to open a file in /sys that doesn't exist. Is there a way to create that file so the program continues? (Normally you can't create flies in sysfs.)
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1answer
131 views

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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28 views

unix executable Error: Reading 0x1b50 bytes extends past end of file for string table

info on the file it is called ld it is a command for linking elfs called link editor. Does Error: Reading 0x1b50 bytes extends past end of file for string table mean I am missing some kind of offset? ...
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1answer
38 views

Replacing firmware, Longshine Shinebook

Am wondering how to replace the firmware on a Longshine Shinebook (manual, firmware, more stuff). Assuming I modify the firmware files, how do I put the new version on the device? I'm guessing there ...
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2answers
522 views

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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0answers
24 views

Why PTRACE_POKEDATA returns I/O error?

I learning usage of ptrace. I tried following simple example but raises a I/O Error. I would like to overwrite "Hello, world" (printing string) from other process. A target program prints &...
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1answer
30 views

Comparing the static address of the vtable of a class, to the pointer to it held by the object

I know this is compiler/ABI dependent, not necessarily standardized, etc. I've always assumed, from what I've read in several places (e.g. an answer here or the example in wikipedia), that a typical ...
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1answer
40 views

What could a firmware image be, if not embedded linux?

I decided to play around with an old baby monitor, purely to learn something about how such things (I.E. embedded devices) work. I successfully extracted the flash memory, and I was expecting this to ...
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1answer
59 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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1answer
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OTOOL alternative for linux

I have a reverse engineering set up on a Mac machine. This set up does some reverse engineering on iOS applications(.ipa files). I'm migrating the setup from Mac to a linux machine. Currently on Mac, ...
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1answer
58 views

Identify strings shared between multiple files from the Linux command line

Given a set of arbitrary files, what's the best way to identify the text strings shared between them (either in all files or a subset of them) from the Linux command line? This would be useful for ...
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1answer
50 views

Program goes to suspend when buffer overflow occurs

Full disclosure: I am seeking help to complete a college assignment. I am seeking help on steps where I am stuck and unable to move forward, not a ready made answer. I need to exploit it to get a ...
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85 views

x64dbg for linux executables?

Is there a x64dbg for Linux executables? I really love x64dbg, but in a lot of CTF challenges there are Linux executables and not .exe files or .dll files.
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4answers
674 views

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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3answers
911 views

Is it possible copy and save bootloader using CLI telnet commands?

I need get copy of original Bootloader from device running embedded Linux. Is it possible copy and save bootloader using CLI telnet commands? I have full access to CLI interface. Is there way copy ...
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25 views

Configure Strace do not parse ioctl command

When I run strace strace -fp 123 -o log -e trace="ioctl" I saw ioctl that strace parse the ioctl command , How can I see the number of ioctl command without parsing?
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1answer
3k views

How to decrypt the config.bin from ZTE ZXV10 H201L

I have this file from my router its backup of user config,I suppose its compresed with zlib and encrypted with AES. Utility which is resposible to compress it and encrypt it is called cspd. In side ...
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29 views

How do I debug Linux kernel modules with IDA?

I'm trying to figure out a workflow for analyzing Linux kernel modules. I want to debug the modules and not just view the disassembly, so I came upon this guide for IDA pro: https://www.hex-rays.com/...
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63 views

Is it possible to intercept syscalls with a custom code from inside the program?

I have a binary calling syscall with a code not present on the Linux kernel. Is it possible that the binary catches the syscall by itself and handles it on-the-fly? Furthermore, what happens if I call ...
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1answer
233 views

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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2answers
931 views

Finding a place to inject shellcode

I am following the tutorial for ROP Primer, level0. The tutorial sets the memory at the beginning of [vdso] writeable and executable and copies the shellcode there. I do not know why, but it seems ...
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1answer
175 views

Need help opening a .img file from a camera firmware (trying to get out of the Meari/Zumimall/PPstrong cloud!)

I've got a cloud-based battery powered camera which I'm really hoping to get out of the cloud with, in order to enable RTSP or ONVIF (or something local!). I've managed to get a .bin file. Binwalk ...
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1answer
207 views

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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2answers
537 views

Extracted router file execution

I am trying to run an executable file that I dug out from an extracted file system of a DSL modem router. So first of all I needed to either have a MIPS Linux box or take the emulation path. After ...
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1answer
368 views

Huawei HG8245H, can't read some system files

I have modem Echolife HG8245H (V3R016C10S150). I'm using telnet to connect it. I need to read some files from this modem. There's a shell mode I can enter, but it is nerfed badly: SU_WAP>shell ...
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2answers
209 views

Where to get started with reverse engineering a usb video device on Windows?

I have a piece of proprietary hardware that I'm trying to reverse engineer and write a cross-platform open-source driver for. This device has an IR camera on it, and it seems to be using the UVC ...
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1answer
335 views

Practicing what SHOULD be a simple crackme. Program calls strlen() but never returns

I'm trying out a crackme from the "LSE CTF" called "Blue Box" worth only 10 points. I've attempted this inside GDB and radare2... It is very simple, takes one argument and first checks to make sure ...
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1answer
23k views

Managing inputs for payload injection?

I am looking for a complete list of the ways to inject a payload in a vulnerable program in a Unix (Linux) context depending on the inputs opened by the program. I know that there are several tricks ...
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4answers
7k views

How can I generate a call graph from an unstripped x86 Linux ELF?

There's a piece of software, for which I only have the binary, not the source code. It's: unobfuscated (so, not polymorphic or anything. It is optimized a bit, though) unstripped x86 32 bit ...
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1answer
470 views

Monitoring Exceptions raised by an executable

Using tools like strace I can figure out the signals a program receives as it executes, regardless of whether or not signal handlers for those signals have been defined. [EDIT] In order to do the same ...
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3answers
16k views

ZTE encrypted backup config file

I was poking around in ZTE Speedport Entry 2i (CPE used mostly in Germany, Slovakia etc, probably custom made for Deutsche Telekom). It's possible to download backup of config from UI. I found out ...
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1answer
51 views

How to split bytes into instructions in binary ELF file for x86

I'm working on a static code injector for ELF files. I need to "steal" some bytes in order to write jump to my code on their place and then execute stolen instructions somewhere in the ...
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1answer
47 views

Call libc functions from the payload statically injected into ELF binary

I am working on ELF-injector, which given some payload (currently it's an assembly file with .text section only) will inject it into ELF binary. I had related post here. Now I would like to make it ...
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3answers
7k views

Use Android Shared library (.so) files in Linux

I decompiled an APK file,and that program have native codes in a .so file. I want to use that .so file in Linux in order to use inline functions. These codes have functions to connect to a server and ...
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1answer
30 views

Why would just two bits of the SP be used here?

This is the section of disassembled code in question. It’s from a Linux kernel module compiled for 4.4.16 on ARMv7. ; Registers used: ; - r3 : unsigned long argp 0000005c mov r1, ...
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1answer
208 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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8answers
30k views

How do I add functionality to an existing binary executable?

I want to add some functionality to an existing binary file. The binary file was created using gcc. Do I need to decompile the binary first, even though I sufficiently understand the functioning of ...
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0answers
24 views

Ollydbg skippingover breakpoint

I am new to the ollydbg world- I am in the middle of injecting shellcode (created with msfvenom...) into a small PE, and during debugging, I can't get it to halt at the breakpoints I set. If I run the ...
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1answer
25 views

can a stdout captured at a parameter to python script

I'm working on a CTF challenge that is find a secret password.This secret password base on the username and password that i input and the hash value had print out after hash calculation and i want to ...
3
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1answer
214 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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4answers
4k views

Identify compression of this ZTE ZXV10 H201L V2 backup config file

This config.bin file is from a ZTE router. I would like to decompress it but I did not identify the compression used in the file. Maybe someone can. 00000000 99 99 99 99 44 44 44 44 55 55 55 55 aa ...
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1answer
54 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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3answers
6k views

Where can I get Linux malware samples?

There have been numerous sites stated in this wonderful post that one could retrieve malware samples. However, I am having a difficult time (sorry D:) locating Linux-specific malware from those sites ...
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2answers
105 views

Newbie problems exploiting a format string vulnerability

I encountered a print format vulnerability challenge in a CTF. I don't know anything about these vulnerabilities, so I'm working my way through Saif El-Sherei's format string exploitation tutorial ...
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1answer
98 views

Does the operating system you use matter?

people recommend windows for reverse engineering, I don't want to install windows as a virtual machine because they are laggy and I already have windows 10 as host, is it possible to use linux vm that ...
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4answers
132k views

Converting assembly code to c

I have the following assembly code over Linux distro: # using the .data section for write permission # instead of .text section .section .data .globl _start _start: # displaying some characters ...
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1answer
271 views

hooking libhoudini on x86 emulator

I'm trying to hook libhoudini to debug an application instruction by instruction using frida but frida not supports it i need a example on how can this be achieved! I'm using a x86 emulator to run arm ...
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2answers
2k views

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

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 to segfault. It should ...

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