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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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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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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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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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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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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349 views

Remote debugger for Linux from one VM (IDA) to another (running the debuggee)

I want to debug a Linux program (ELF), but my IDA Pro is on a Windows 10 VM and I want to use remote debugging to debug the program on Ubuntu (also in a VM). So, is it possible to debug if both ...
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349 views

Linux Assembly Syscall

I'm learning how to write shellcode by using Linux system call "execve" to spawn a shell with root access privilege. Here i found a shellcode online: http://shell-storm.org/shellcode/files/shellcode-...
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IDA remote linux Debugger attach to a running process

I usually use remote linux debugger as shown below: ./linux_server bin And in IDA Pro, I select Remote Linux Debugger as the debugger and set the process options accordingly with the IP address and ...
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872 views

Linux x64 Disassembly: single movzwl operand question

A quick question regarding a movzwl instruction which do not behave as I expected. here is the disassembled code: movzwl (%rax),%eax Before the instruction, rax is 0x7fffffffe410 and point to 0x5 ...
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338 views

My nopsled getting Segmentation fault (core dumped)

After overwrite the EIP register, I try breakpoint on the function strcpy() and then run the program after a breakpoint in the debugger. Then I check the ESP register : (gdb) i r esp esp ...
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How is linux loaded into a closed platform that has been hacked?

Today I have a question which may be a little uncertain. How would you "port" the Linux OS to a new platform? For example; The nintendo 3ds or the PS4, are consoles which have been recently "hacked", ...
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Extract YAFFS filesystem from binary

Iv got firmware from vivax set-top box backed up on flash drive and I vould like to change splash screen on it. The firmware seem to be yaffs but I cant extract files in order to change something. :~...
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How to decrypt data in binary file by XOR operator using a given key at specific offset? [closed]

I've a binary data files which are encrypted by a simple XOR cipher using a given key at offset +0x88 (which is 0x80 long), then the data (+0x108) is compressed by lzo1x. What would be the most ...
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1answer
81 views

How to get the input necessary to get to the end

In short, I have a code that gets an input via stdin. Once it has the input string in memory, it verifies its integrity by calling a function for every condition, and exiting the program if those ...
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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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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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132 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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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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69 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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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
199 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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56 views

Exploit education stack-five: trouble getting the shell

Im trying the phoenix vm, challenge stack-five on exploit.education (http://exploit.education/phoenix/stack-five/). I run onto a problem while exploiting a stack overflow. The challenge is run execve('...
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137 views

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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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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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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Executing MIPS binaries on Ubuntu Linux

I have a 32-bit MIPS binary and I'm trying to execute it on Ubuntu 64-bit. file command for the binary shows: bin: ELF 32-bit MSB executable, MIPS, MIPS32 rel2 version 1 (SYSV), dynamically linked (...
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117 views

What is the name of this technique?

A while back, on a Linux system, I found a strange binary being executed at seemingly random times with some strange arguments, briefly appearing in ps. There was nothing to be found at the usual ...
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65 views

What memory security settings are needed to allow a basic buffer overflow on Fedora 25?

I'm having a rather difficult time determining what memory security settings need to be adjusted on a fresh install of Fedora 25 in order to perform basic buffer overflows in the C language. As a ...
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1answer
120 views

Intel PIN and nm unable to capture binary symbols

I'm trying to generate a log of all identified symbols in a binary file. The application i'm trying to inspect is busybox. I've created a Pin Tool that successfully captures symbols (no demangling) ...
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73 views

dlmalloc free pointers

I was looking at the implementation of "free" in my current dlmalloc(both the source and the disassembly). However, I could not find the code section the inserts the FD and BK into free chunks. What ...
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1answer
152 views

Finding “free” inside libc.so

I extracted the libc.so.6 from within a vulnerable image used for exploitation purposes. I open up the shared object in IDA and I look at the symbols inside the "Exports" tab. I find "free"; upon ...
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395 views

Intercepting syscall in a shared object (dynamically linked)

Ditto. Any technique that allows to intercept sys calls issued from a shared object file? At runtime, the shared object is dlopen'ed by main(). One candidate is to use static binary rewriting (e.g. ...
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471 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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126 views

Set up an interrupt handler at kernel mode

I'm looking for something (a tool?) that can help me achieve my current goal: write a driver that can momentously interrupt the execution of the operating system (Linux, in my case), let me be able to ...
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2answers
622 views

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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2answers
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Formatting output of objdump -sj .text filename.exe

I am hoping to get the contents of the .text section, of a Microsoft PE file using a linux command. When I use objdump -sj .text filename.exe the output consists of the offset, in hexadecimal ...
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1answer
384 views

Error: Invalid PE header machine value with pedump

I would like to dump the .text section on MS Windows .exe PE files in Ubuntu 14.04.4. I install pedump, on my Ubuntu system using sudo apt-get install mono-utils When I tried running pedump code /...
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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 ...
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2answers
65 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
1k views

Dynamic Analysis on ELF using IDA

On Linux, while generally reversing ELF files and dynamic analyzing (like step into, step over, break-point, inspecting registers value, memory etc) I use gdb or radare2 which provides dynamic ...
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1answer
336 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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0answers
601 views

Allwinner Camera Reversing: Compiling V4L [closed]

I've reverse engineered quite a bit of action cameras based on Allwinner's poorly documented chipset. It runs firmware closely related to H3, in fact I can compile a kernel that boots with no video ...
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2answers
479 views

Stopping at the original entry point in a packed file

During manual unpacking, the first task is to find to original entry point. The program jumps there after the unpacking is done. I took the bin/ls file, and checked with readelf -h that the entry ...
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2answers
158 views

Looking for reverse engneer online course [duplicate]

I looking for online reverse engeneer course. Course that study ida,reverse and patch for windows/ linux. Working with ida and another tool. I like many videos lesons. Do you know one?
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1answer
83 views

Which environment are comfortable for RE ( Free tool ) [closed]

I'm a beginner in RE. So i don't know which environments are better for me ( Linux or Window , 32bit or 64bit ). Which free tools are the best for each OS . Ollydbg is for Windows 32bit right?
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How can I turn .deb files back to .tar for reuse with other Linux distros? [closed]

We all know that Ubuntu is the most popular Linux distro today with plenty of application currently being developed for it. But then I use Fedora and some use other distros but still liked to have the ...

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