Invoke-CradleCrafter: PowerShell Remote Download Cradle Generator & Obfuscator
Invoke-CradleCrafter v1.1
Introduction
Invoke-CradleCrafter is a PowerShell v2.0+ compatible PowerShell remote download cradle generator and obfuscator.
Background
In the Fall of 2016 after releasing Invoke-Obfuscation, I continued updating my spreadsheet of PowerShell remote download cradles thinking that one day I might add a “cradle selector” menu into Invoke-Obfuscation. This list consisted of cradles that were obscure to me, and many of which were not prevelently (or at all) being observed in the wild.
However, since Invoke-Obfuscation was designed to obfuscate any arbitrary PowerShell command or script, there are certain obfuscation techniques that I knew I needed to include with regards to building customized cradles that were not feasible to include in Invoke-Obfuscation.
This was the point that led me to shift this cradle research into a separate project altogether, though you can always take output from Invoke- CradleCrafter and intput it into Invoke-Obfuscation and continue the fun. Since Invoke-CradleCrafter is much more tightly controlled, it has enabled me to include obfuscation techniques that are completely unlike any technique found in Invoke-Obfuscation.
Some of the new obfuscation techniques in this tool include token obfuscation through data type enumeration and wildcard matching, and the reordering of command structure by introducing additional variables and variable syntaxes.
Lastly, the tool supports 10+ invocation syntaxes that extend beyond the most prevalent Invoke-Expression and IEX.
Purpose
Invoke-CradleCrafter exists to aid Blue Teams and Red Teams in easily exploring, generating and obfuscating PowerShell remote download cradles. In addition, it helps Blue Teams test the effectiveness of detections that may work for output produced by Invoke-Obfuscation but may fall short when dealing with Invoke-CradleCrafter since it does not contain any string concatenations, encodings, tick marks, type casting, etc.
Another important component of this research and tool development was to effectively highlight the high-level behavior and artifacts left behind when each cradle is executed. I have tried to highlight this information when you first enter a new cradle type in the interactive menus of the tool.
Ultimately, knowing more about each cradle’s behavior and artifacts will help the Blue Team better detect these cradles. This knowledge should also benefit the Red Teamer in making more informed selections of which cradle to use in a given scenario.
Usage
While all of the cradles can be produced by directly calling the Out-Cradle function, the complexity of the moving pieces for all of the stacked obfuscated components makes using the Invoke-CradleCrafter function the easiest way to explorer and visualize the cradle syntaxes and obfuscation techniques that this framework currently supports.
Installation
The source code for Invoke-CradleCrafter is hosted at Github, and you may download, fork and review it from this repository (https://github.com/danielbohannon/Invoke-CradleCrafter). Please report issues or feature requests through Github’s bug tracker associated with this project.
To install:
