I have to admit that I am a bit late to the party, but I see this as an opportunity to try out SET and learn a bit about the DLL hijacking issue at the same time.
Last Thursday, Acros, a Slovenian security firm, published an advisory that identified what they call a “binary planting” flaw in iTunes. Essentially, if you open a file type associated with iTunes from a remote network share, iTunes will also try to load one more DLLs from the share. Even if the file that the user opened is completely safe, a malicious DLL can be supplied that will lead to code execution.
HD Moore stated “While working on the Windows Shortcut exploit, he stumbled on this class of bugs and identified a couple dozen applications that seemed to be affected by this problem. iTunes was one of these applications and the details in the Acros advisory made it clear that this was indeed the same flaw. He was planning to finish the advisories and start contacting vendors on August 20th (last Friday). The Acros advisory on the 18th threw a wrench into this process.
Microsoft later release the following details in an advisory:
Microsoft is aware that research has been published detailing a remote attack vector for a class of vulnerabilities that affects how applications load external libraries.
This issue is caused by specific insecure programming practices that allow so-called “binary planting” or “DLL preloading attacks”. These practices could allow an attacker to remotely execute arbitrary code in the context of the user running the vulnerable application when the user opens a file from an untrusted location.
This issue is caused by applications passing an insufficiently qualified path when loading an external library. Microsoft has issued guidance to developers in the MSDN article, Dynamic-Link Library Security, on how to correctly use the available application programming interfaces to prevent this class of vulnerability. Microsoft is also actively reaching out to third-party vendors through the Microsoft Vulnerability Research Program to inform them of the mitigations available in the operating system. Microsoft is also actively investigating which of its own applications may be affected.
In addition to this guidance, Microsoft is releasing a tool that allows system administrators to mitigate the risk of this new attack vector by altering the library loading behavior system-wide or for specific applications. This advisory describes the functionality of this tool and other actions that customers can take to help protect their systems.
- This issue only affects applications that do not load external libraries securely. Microsoft has previously published guidelines for developers in the MSDN article, Dynamic-Link Library Security, that recommend alternate methods to load libraries that are safe against these attacks.
- For an attack to be successful, a user must visit an untrusted remote file system location or WebDAV share and open a document from this location that is then loaded by a vulnerable application.
- The file sharing protocol SMB is often disabled on the perimeter firewall. This limits the possible attack vectors for this vulnerability.
Demo Time with SET… Thanks to Dave for his wonderful video that he posted this afternoon, I can now use this as my base for this demo.
What is SET?
The Social-Engineer Toolkit (SET) was designed by David Kennedy (ReL1K) and incorporates many useful Social-Engineering attacks all in one simplistic interface. The main purpose of SET is to automate and improve on many of the social-engineering attacks out there. As pentesters, social-engineering is often a practice that not many people perform. You can download the Social-Engineering Toolkit through subversion by simply typing this in Back|Track 4 or any other Linux OS.
However BT4 now comes with SET located under /pentest/exploits/set, from here you can simply launch SET with a ./set and get your latest updates by selecting option 8.
SET can do tons of cool stuff and I have included a few links at the end of this post that explains them in details, and I have a few post to come that will also go into some more details. However for todays demo I will only be using a few of those features.
Launch and update SET
If you are using BackTrack4 you can find SET located under /pentest/exploits/set, you can launch it with ./set and as stated above select option 8 to get the latest and greatest updates.
Choose your path to pwnage
I selected Option 2 or “Web Attack Vectors” which is a unique way of utilizing multiple web-based attacks in order to compromise the intended victim.
Select option 2 once more “The Metasploit Browser Exploit Method” this method will utilize select Metasploit browser exploits through an iframe and deliver a Metasploit payload.
And yet again select option 2, “Site Cloner” this method will completely clone a website of your choosing and allow you to utilize the attack vectors within the same web application you were attempting to clone.
Choosing your browser Exploit:
At this point you have several options to choose from, today we will be picking option 1 “Microsoft Windows WebDAV Application DLL Hijacker”.
Choosing your Payload:
Once more you are giving several options, I choose option 2 “Windows Reverse_TCP Meterpreter“, this payload will spawn a meterpreter shell on the victim and send it back to the attacker.
Once you are done, you have to choose your vulnerable extension types if you are not certain select enter to choose the defaults, or find a semi-complete list over at exploitdb . At this point the malicious iframes are infected into the cloned website and awaits your victim.
SET Mass E-Mailer Option :
There are two options on the mass e-mailer,we are choosing option1 this option will allow you to send an email to one individual person. Once you are done you have to choose who you would like to send the phishing email too, and who is your sender lastly figure if you would like to use Gmail, your own mail server or some open relay server.
Next think of something clever as a email subject and body. A good example would be to clone a local web-based system from your attacker network and send an email saying “we are doing some updates kindly click to verify you can access this test link. After you are finish click Ctrl + C and hit enter to complete this step. You will then receive a message stating that SET has already sent the email. Now is just a matter of waiting on your victim to click the email and check out the vulnerable files via the network share.
Exploit in action..
Once your victim clicks on the link, the will be presented with the cloned site at first then the exploit will begin doing its thing in the background. Shortly after the user will be presented with a network share with the vulnerable files. After opening up the file it its Game Over.
Since the initial reporting of this issue, many researchers have came out with several ways of doing this so far some of my favorites are:
- Using msfconsole courtesy of the guys HDM in this post.
- Using msfpayload courtesy of Matt over at http://www.attackvector.org/alternative-dll-hijacking-method/
- Yet again Matt demoing using msfpayload + autorun usb stick http://www.attackvector.org/autorun-dll-hijacker-usb-stick/
I have tested several of these and noticed that MSE AV was effective in identifying the msfpayload file, however using the standard method I successful exploited both windows XP and Windows 7.