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How to Exploit the Buffer Overflow Vulnerability in Ability FTP Server 2.34 Full Version


How to Exploit the Buffer Overflow Vulnerability in Ability FTP Server 2.34 Full Version




If you are interested in learning how to exploit buffer overflow vulnerabilities, you may want to try Ability FTP Server 2.34 full version, which is a File Transfer Protocol (FTP) server software that has a known buffer overflow vulnerability in its FTP STOR command. This vulnerability allows a remote authenticated attacker to send a specially crafted file name that can overflow a buffer and overwrite the return address on the stack. By doing so, the attacker can gain control of the program execution and run malicious code on the server.




Ability FTP server 2.34 vulnerable buffer overflow full version



In this article, we will show you how to exploit the buffer overflow vulnerability in Ability FTP Server 2.34 full version using a simple Python script and a Metasploit payload. We will also explain how the vulnerability works and what are the risks and consequences of exploiting it.


What is Ability FTP Server 2.34 Full Version?




Ability FTP Server 2.34 full version is a File Transfer Protocol (FTP) server software developed by Code-Crafters Software Limited. It allows users to transfer files between computers over a network or the internet. It supports various features such as SSL/TLS encryption, virtual file system, user accounts, IP filtering, and logging.


Ability FTP Server 2.34 full version was released in 2004 and has been discontinued since then. The current version of the software is Ability FTP Server 3.0 which was released in 2019 and is not affected by the buffer overflow vulnerability.


What is the Buffer Overflow Vulnerability in Ability FTP Server 2.34 Full Version?




The buffer overflow vulnerability in Ability FTP Server 2.34 full version is a type of memory corruption vulnerability that occurs when a program does not properly validate the length or format of the input data before copying it to a fixed-size buffer. A buffer is a region of memory that is allocated to store data temporarily. If the input data is larger than the buffer size or contains unexpected characters, it can overflow the buffer and overwrite the adjacent memory locations. This can cause unpredictable behavior of the program such as crashing, malfunctioning, or executing arbitrary code.


The buffer overflow vulnerability in Ability FTP Server 2.34 full version exists in the FTP STOR command which is used to upload files to the server. The FTP STOR command takes a file name as an argument and stores it on the server under that name. However, the Ability FTP Server 2.34 full version does not check the length or format of the file name before copying it to a 256-byte buffer on the stack. Therefore, if an attacker sends a file name longer than 256 bytes or containing non-ASCII characters, it can overflow the buffer and overwrite the return address on the stack.


The return address is a memory location that stores the address of the next instruction to be executed after returning from a function call. By overwriting the return address with a malicious value, an attacker can redirect the program execution to an arbitrary location where he can run his own code.


How to Exploit the Buffer Overflow Vulnerability in Ability FTP Server 2.34 Full Version?




To exploit the buffer overflow vulnerability in Ability FTP Server 2.34 full version, we need to do the following steps:


  • Set up a vulnerable server running Ability FTP Server 2.34 full version on a Windows XP machine.



  • Create an account on the server with write permissions.



  • Generate a shellcode payload using Metasploit that will open a reverse shell connection to our attacker machine.



  • Create a Python script that will send a malicious FTP STOR command containing our payload and overwrite the return address on the stack.



  • Run our Python script and connect to our shellcode payload using Metasploit.



  • Enjoy our remote shell access to the server.



Step 1: Set up a vulnerable server running Ability FTP Server 2.34 full version on a Windows XP machine




We need to set up a vulnerable server running Ability FTP Server 2.34 full version on a Windows XP machine for testing purposes. You can download Ability FTP Server 2.34 full version from here and install it on your Windows XP machine following these instructions. You can also use a virtual machine such as VirtualBox or VMware for this step.


After installing Ability FTP Server 2.34 full version, you need to activate it using any serial number such as "1234567890". You also need to configure some settings such as port number, root directory, user accounts, etc. You can refer to this guide for more details.


Step 2: Create an account on the server with write permissions




We need to create an account on the server with write permissions so that we can upload files using FTP STOR command. You can do this by opening Ability FTP Server 2.34 full version and clicking on "Users" tab. Then click on "Add" button and enter your desired username and password. Make sure you check "Write" option under "Permissions" section and select your root directory under "Home Directory" section.


Step 3: Generate a shellcode payload using Metasploit that will open a reverse shell connection to our attacker machine




We need to generate a shellcode payload using Metasploit that will open a reverse shell connection to our attacker machine when executed on


Step 4: Create a Python script that will send a malicious FTP STOR command containing our payload and overwrite the return address on the stack




We need to create a Python script that will send a malicious FTP STOR command containing our payload and overwrite the return address on the stack. Python is a high-level scripting language that is easy to use and has various libraries for network programming.


To create our Python script, we need to use the socket library which provides low-level access to network interfaces and the struct library which provides functions for packing and unpacking binary data.


We also need to know the following information:


  • The IP address and port number of the vulnerable server.



  • The username and password of our account on the server.



  • The offset value of the buffer overflow which is the number of bytes we need to fill before overwriting the return address.



  • The return address value which is the memory location where we want to jump after overwriting the return address.



  • The NOP sled value which is a series of no-operation instructions that will slide the program execution to our payload.



  • The shellcode payload value which is our malicious code that will open a reverse shell connection to our attacker machine.



For example:


# Import socket and struct libraries


import socket


import struct


# Define server IP address and port number


server_ip = "192.168.1.101"


server_port = 21


# Define username and password