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Showing posts from December, 2018

SharpNado - Teaching an old dog evil tricks using .NET Remoting or WCF to host smarter and dynamic payloads

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TL;DR:

SharpNado is proof of concept tool that demonstrates how one could use .Net Remoting or Windows Communication Foundation (WCF) to host smarter and dynamic .NET payloads.  SharpNado is not meant to be a full functioning, robust, payload delivery system nor is it anything groundbreaking. It's merely something to get the creative juices flowing on how one could use these technologies or others to create dynamic and hopefully smarter payloads. I have provided a few simple examples of how this could be used to either dynamically execute base64 assemblies in memory or dynamically compile source code and execute it in memory.  This, however, could be expanded upon to include different kinds of stagers, payloads, protocols, etc.

So, what is WCF and .NET Remoting?

While going over these is beyond the scope of this blog, Microsoft describes Windows Communication Foundation as a framework for building service-oriented applications and .NET Remoting as a framework that allows objects li…

Evading Sandboxes and Antivirus Through Payload Splitting

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Malware has been using the Temporary Internet Files folder structure as a launching point for the past 20 years, but from an offensive standpoint I haven’t seen too much else that leverages the quirks and functionality it can provide.A few weeks back during an engagement I was on, I noticed the wide variety of filetypes present in the folder structure that appeared to be directly downloaded from the internet and were in no way were obfuscated, compressed, or restricted. Due to a few other projects I was working on at the time, I started thinking to myself about the potential implications of this, as well as the limits to which it could be taken.The result of this research was the discovery of a technique of splitting payloads to evade antivirus and sandboxes, as well as provide a potential new method for payload encryption / environmental keying.
As a part of penetration tests I find myself more often hosting payloads on a third-party site and then sending a link to the site in the …