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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238 views

What checksum algorithm is this network protocol using?

I've been working my way through an undocumented TCP-based protocol by monitoring traffic with tcpdump, Wireshark, and some Python packages (scapy, numpy) with good luck so far, but I've hit a wall ...
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1answer
664 views

Kernel dealing with the section headers in an ELF

I recently read that the kernel and the dynamic loader mostly deal with the program header tables in an ELF file and that assemblers, compilers and linkers deal with the section header tables. The ...
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118 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
37 views

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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1answer
116 views

Lipo alternate for linux

Currently, I'm using lipo tool to extract the arch type from a fat iOS binary on a Mac OS. Now, I want to do the same on the linux platform for the iOS binaries, i.e. extract a given arch type from a ...
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1answer
97 views

Fork and Waitpid calls in a CTF linux binary

I'm doing one of my first linux crackmes. In the first blocks of code, it goes inside some anti-debug routine and inside one of those it forks and after it calls a waitpid routine. I can verify it ...
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1answer
563 views

Rebuilding firmware back to binary file

I used Binwalk to extract firmware files, extracted content include 2 folders and one binary file. squashfs-root _351C.extracted 351C Squashfs-root contains file system, '_351C.extracted' folder ...
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2answers
632 views

IDA Pro - Applying function signatures

I have three files: ELF executable, ELF dynamically linked library (.so), C headers file (.h) with function signatures and related structures for that library. #1 imports a number of functions from #...
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1answer
1k views

IDA Pro debugging: follow child process

I'm reverse engineering a malware that creates a number of child processes and I'm trying to do dynamic analysis of the ELF binary with IDA Pro and IDA's Local Linux Debugger, but I can't get IDA to ...
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1answer
93 views

Is it possible to restart over a program by calling an entry point function?

I was wondering if it was possible to restart a program (ignoring previously mapped files) with different argument by either calling main() or a glibc entry point function.
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219 views

Is it possible to rebuild an nexe file if I can read at arbitrary untrusted memory addresses?

Ok, I’m in a remote situation where I don’t have access to the remote filesystem but where I can run arbitrary python code (except I can’t fork processes and I don’t have access to ulimit and uname). ...
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1answer
819 views

One shellcode works, one doesn't - an issue with exploiting a 64 bit linux binary

I'm working on exploiting a simple 64 bit linux binary. I got control of RIP by exploiting a buffer overflow and using a jmp rsp to get control of the progrm. However, I'm having trouble with the ...
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224 views

How do I restore modified firmware to a read only mount

I have managed to get a root shell on my web filtering router by plugging into a UART on the PCB which allowed me to see a process (lockbox.bin - ELF executable) running which handles most of the ...
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1answer
1k views

Erase the data from the NVRAM

Cable modem SPI Flash memory have the following structure: 7 cmdlinepart partitions found on MTD device spansion partitions[0] = {.name = U-Boot, .offset = 0x00000000,.size = 0x00020000 (128K) } ...
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1answer
649 views

In-circuit programming of SPI Flash memory

Is it possible to define (using only visual inspection of PCB and multimeter) whether or not SPI Flash memory can be properly programmed keeping the device In-circuit, without desoldering IC from the ...
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1answer
1k views

ldd showing absolute path only

Under what circumstances does the output of ldd have only the absolute path? In the below eg, /usr/lib/arm-linux-gnueabihf/libcofi_rpi.so and /lib/ld-linux-armhf.so.3. pi@raspberrypi ~ $ uname -a ...
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62 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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64 views

Decrypt ibt.sfi linux firmware(Intel Wireless 8265 Linux Bluetooth)

Why I want to decrypt: Intel 8265 Bluetooth is likely a RAMUSB device, which needs system to update firmware. I try to transplant this linux firmware to macOS. Problems I met: The macOS BT firmware ...
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560 views

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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258 views

Reverse Engineering Linux Core Dump

I have a Linux Core Dump file for a binary (which apparently crashed during execution) file command on the core dump: core.123: ELF 64-bit LSB core file x86-64, version 1 (SYSV), SVR4-style, from '/...
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0answers
264 views

Passing input to program in Remote Debugging with IDA Pro

I am writing an exploit for a binary on Linux using IDA Pro. This binary, first accepts an input using getchar() and after few more code sections, it accepts a buffer as an input through stdin and it ...
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637 views

Unable to install ltrace on Kali [closed]

I am kind of stuck with the installation of ltrace on my Kali VM. My /etc/apt/sources.list file is updated with following entry: deb http://http.kali.org/kali kali-rolling main non-free contrib I ...
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111 views

Immunity error BB010002

I am trying to make this exploit work and having some difficulty. So I skipped to a 'fixed' version of it from here and the only thing I changed was the shell code: https://github.com/cokebottle/oscp-...
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92 views

Unsquashfs fails partways with gzip error code -5

I have been trying to unsquash a system.sfs file in order to modify the directories. however, unsquashfs system.sfs returns the following output: Parallel unsquashfs: Using 8 processors 1 inodes (...
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546 views

My core dump's backtrace stops to a signal handler, what can I do?

I obtained an ELF core dump that was provoked by fuzzing a proprietary server. As I do not have access anymore to the machine that hosted this server, and the server is part of a tightly coupled set ...
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1answer
137 views

library issue when running mips binary in a chrooted environment

Background In my endeavor to RE my router, I'm trying to emulate a router's firmware inside a QEMU MIPS system. I have debian-mips installed to a virtual disk that runs just fine. Its a MIPS32 Big ...
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1answer
533 views

Why always get the message “Illegal Instruction (core dumped)”?

I tried to exploiting buffer overflow. In the exploit code I use the Aleph-One shellcode. "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b" "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\...
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178 views

X64 ASSEMBLY - Cannot run compiled and linked raw shellcode in Windows

After using metasploit's windows/x64/meterpreter/reverse_tcp shellcode on my windows 10 machine (with AVs turned off), I decided to try to create a hand-made polymorphic, null-free and custom-encoded ...
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468 views

Is there a way to debug an elf file that runs with no problems with damaged header?

My question is general, but to have an example to work with, let us take one from Whirlwind Tutorial. ; tiny.asm BITS 32 org 0x00010000 db 0x7F, "ELF" ; ...
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114 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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525 views

ZyXEL P-2812HNU-F1, replacing the U-Boot on the board

I want flash regular(non branded) firmware on ZyXEL P-2812HNU-F1 router, which have branded version of firmware (customized for local MSO provider). To do this, I should first replace the U-Boot image ...
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527 views

Reverse Engineering Wifi Chip-set Firmware [closed]

I have Sparrow Wireless Adapter which from Qualcomm originally Wilocity that supports Wifi over 60 GHz (802.11ad or WiGiG). I have the firmware files of the wireless chipset (wil6210.fw and wil6210....
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1answer
3k views

Unable to view stack and memory addresses in IDA Pro [duplicate]

I am debugging a 32-bit ELF executable using remote GDB debugging option of IDA Pro. However, I am unable to view the contents of stack in the stack view. Also, the stack pointer value is: 0xFFFFD328 ...
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1answer
233 views

Mechanisms to stop serial console accepting input on a Linux system?

I am working on a simple embedded system based around an Olinuxino board. This has a serial console header onboard. TX and RX are both connected to the respective pins on the microcontroller (i.e. ...
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310 views

Why the extracted content differs?

I used binwalk to extract firmware.bin image, the extracted content is squashfs-root dir, and a separate dpc.squashfs file. Then I used sasquatch utility to extract content of dpc.squashfs file, and I ...
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293 views

Where can i find unix/linux tool for fuzzing for kill-switches? [closed]

I'm looking for linux/unix open-source tools for fuzzing ethernet card for kill-switch packets. https://en.wikipedia.org/wiki/Fuzzing I can imagine how it would be long to brute full of range on ...
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4answers
3k views

Can IDA Pro on Linux disassemble a Windows PE (or Mac OS X app)?

I am thinking of buying IDA Pro for my Linux programming environment after reverse engineering a bit with OllyDBG (under WINE)... But before I endorse into such a costly purchase I ask the following ...
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1answer
5k views

Reverse engineering a golang binary file

I compiled docker by myself with some modifications. I would like to perform some static analysis to the binary. Mostly to see which parts of the code take more memory, etc. It's on linux (elf). Any ...
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260 views

How to interpret disassembled MIPS code?

I have disassembled MIPS binary with raw opcodes. How to interpret, for example, these lines: Disassembly of section .data: 00000000 <.data>: ... ... f864: 30a5ffff sd ra,-23248(...
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1k views

Adding additional language to Linux based Firmware of Volkswagen Car Radio

I'm owning a CarPlay head unit from Volkswagen called RCD330 plus. It is possible to upgrade/downgrade to any available firmwares. For example here are two firmware versions: http://rcd330plus.com/rcd/...
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2k views

Recognize the library functions of statically linked executable file in IDA Pro

Recently I worked on a Linux program which has all of its symbols stripped. Opening it with IDA resulted in none of its functions identified. Thus I tried to extract any usable information from the ...
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3k views

Limited BusyBox shell

I'm testing some embedded device, and there is lack of documentation. When I telnet to device, I get only limited shell. BusyBox v1.19.2 (built-in shell (ash) Enter 'help' for a list of built-in ...
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1answer
55 views

Significance of link address 2000 8000 7C00;

Can you explain to me the significance of link address 2000 8000 7C00? It's in a MACRO from the GRUB configure script, which checks whether OBJCOPY works for absolute addresses. Here's the snippet ...
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2answers
796 views

How to know the arguments of a Linux syscall?

To my knowledge, this is a decent resource to know the parameters of a Linux syscall. However, this only lists 32 bit syscalls, not the 64 bit ones. Moreover, the reference doesn't say which register ...
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1answer
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Unpacking firmware

I have a ROM dump firmware which must be reversed (as a task). Binwalk output: DECIMAL HEXADECIMAL DESCRIPTION -------------------------------------------------------------------------------...
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What is causing \r\n in libnotify? [closed]

I am trying to look under the hood of libnotify, and ran strace notify-send 'hello' and one of the system calls is: sendto(5, "AUTH\r\n", 6, MSG_NOSIGNAL, NULL, 0) = 6 Surrounded by a: sendmsg(5, {...
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96 views

How do I go about overriding a function internally defined in a binary on Linux?

To be specific, I cannot recompile this binary, nor do I have access to the sourcecode. The functions are not defined within a shared library. So, how can I go about changing a function, or ...
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1answer
211 views

x64 Linux reverse-engineering - understanding asm code and inject eax

In a rootme exercise, i'm trying to bypass the control impleted to protect a "read" function. You'll find enclosed the code i'm refering to. As you may understand, i can inject data (with limitations) ...
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1answer
60 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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1answer
55 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 ...