Lately I’ve been playing around with Visual Studio Tools for Office (VSTO) as a persistent foothold. VSTOs are Microsoft Office add-ins that can enhance the user’s experience or automate tasks. Enabled add-ins are run every time the target Office application is started, a perfect persistence point. VSTOs can be written in C# or VB, and if done correctly, do not require administrative privileges to install.
Because of this event driven nature and the non-admin installation, I think VSTOs could be a decent addition to a phishing installation package. I’ve put together a proof of concept which can be found at https://github.com/ThunderGunExpress/ThunderVSTO
What This is Not
A complete installation package. This persistent VSTO would need to be included in some sort of a larger installation package. Fortunately, I plan on posting about this at a later date.
How to Defend
Sysinternals Autoruns checks for Office add-ins; however, unless I’m missing something, it only displays the HKLM\Software\Microsoft\Office\**Office App**\Addins. Personally, I would target HKU instead (non-admin) which is not tracked by Autoruns.
Continue reading “Persistent VSTO”
This really isn’t much of a post; instead, I wanted to show some love for https://www.hackthebox.eu/ which a friend recently introduced me to. I just started to work my way through some of the challenges and I think it’s very well done.
We all know that UAC is not a security boundary. That being said, it can be super annoying, and sometimes difficult, when you just want to spawn a window-less high integrity session so you can continue with funtimes.
Recently I came across the technique described on Tyranid’s Lair to bypass UAC, but I could only find Powershell implementations like UAC-TokenMagic and Invoke-TokenDuplication. So to take a different route, I put together a reflective DLL that uses this technique and an Aggressor script to make everything easy.
The DLL creates a duplicate token for wusa.exe, crafts a new restricted token, spawns an elevated hidden instance of cmd.exe, and proceeds to inject shellcode into cmd.exe via RTLCreateUserThread. I’ve tested it on Windows 7, 10, 2008, and 2012 on both x64 and x86 architectures.
Lately I’ve been neglecting my CTF posts so I could put some time into OutlookToolbox, a C# DLL that uses COM to target Outlook in the background. Additionally, I put together a Cobalt Strike Aggressor script to assist with the execution of OutlookToolbox, both of which can be found at the repository here – https://github.com/ThunderGunExpress/OutlookToolbox.
This is a quick and dirty post which will cover the features. Later, I plan on creating another post which further explores potential use cases of OutlookToolbox.
- Only use for good.
- I have not done extensive testing with this tool, use at your own risk. I recommend testing OutlookToolbox on a replica of your target first.
- The Aggressor script uses several brm (file and/or directory remove) function calls which can bulldoze entire directories if input is not sanitized correctly. I’ve tried to iron out all the issues, but still, I would put OutlookToolbox in a non-critical directory like C:\Users\Public\Documents just to be safe.
What it Does
- Lists folders in Outlook (Inbox, Sent Items, Conversation History, Joe’s Custom Folder … )
- Exports target folder to a CSV File
- Enumerate targets using the GAL
- Download specific messages
- Sends an email on behalf of the target user
How to Prevent
Configure Outlook’s programmatic access security to report on suspicious activity – MS link. Email encryption will cause several of these functions not to work, not a bad idea.
Continue reading “OutlookToolbox”
Lately, I’ve been dedicating my spare time to Pentestit v11, a terrific pentest lab which is great to hone those skills. If you have the spare time, I highly recommend participating – lab.pentestit.ru.
Version 11 is named “Who is Mr. Hacker?”. To start, we are given a network diagram and two target IP addresses: 192.168.101.10 and 192.168.101.11. For this post, I’ve created my own network diagram so I can mark it up along the way.
Obviously there are spoilers ahead.
Continue reading “Pentestit v11”
Just a FYI, this is more or less a placeholder post with little content until I upload a walk-through.
While surfing reddit/netsec someone posted a link of a walk-through of some targets in a virtual pentest lab called practicalpentestlabs, naturally I decided to give it a go.
To join the game, it’s as simple as registering and establishing a VPN session into the lab environment via openvpn. Target IP addresses are provided, and depending on the difficulty, a little hint giving potential avenues of attack. The goal is to hack into each of the targets and grab the contents of secret.txt, which usually resides in /root or the administrator’s desktop. The contents of secret can then be submitted for points, the amount awarded is based on the difficulty of the target. Accumulated points are tracked on a pretty slick dashboard … sorry I couldn’t help myself :S
At the moment, I’ve worked through the web application and scenario based targets with the exception of “X”. I thought the targets were challenging but not insanely difficult. Practical pentest labs was a great walk-through of various vulnerabilities while not obscuring them to a point where it’s less an exploitation exercise, and more a game of hide and seek. Continue reading “Practical Pentest Labs”
In the previous post we discussed using Responder with Snarf, this post will be doing the same but through a pivot. To pivot in we’ll be using Simpletun and a layer 2 pivoting client, this will give the ability to assign an IP address to an interface on our attacking VM, listen for broadcasts, and where available, respond. Commercial products Metasploit Pro and Cobalt Strike have this feature built-in and perform the pivot via encrypted channels, if you are not intentionally looking to get caught by Blue Teams, use them. Another option is Inveigh, a powershell LLMNR/NBNS spoofer with relay capabilities that is included in Empire and available for pivot poisoning without the layer 2 tunnel.
Continue reading “Responder and Layer 2 Pivots”
This post is about using Responder and Snarf to poison broadcasts, SMB relay, enumerate privileges and files, and when we choose, spawn a shell. Bonus post includes doing all of the above through a pivot.
I would imagine the majority of the offsec crew can appreciate Responder and all that it can do. Using in UNION with SMB relay, it can be a great way to get that first shell or enumerating sensitive files. The good old days where we can relay back to the source are long past us (well I hope), but that doesn’t mean we should dismiss this as a potential wedge point.
Continue reading “Responder and Snarf”