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Showing posts from May, 2021

Assembly.Lie – Using Transactional NTFS and API Hooking to Trick the CLR into Loading Your Code “From Disk”

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  Introduction: Assembly.Load, a method that has been one of the primary reasons for the meteoric rise in offensive tooling written in C# over the past few years.  Its most commonly used overload in offensive tooling – Assembly.Load(byte[]) allows for memory-only loading of .Net assembly objects (.exe / .dll) directly from a byte array representing the object’s contents, effectively granting the ability to reflectively load and execute a program entirely in memory in just 2-3 lines of code. This has enabled all sorts of multi-staged payloads, modular program functionality, and fileless post-exploitation operations.  A few months back some tooling I was working on caused me to take a closer look into the mechanisms behind loading assemblies into the .net Common Language Runtime (CLR).  I found that while Assembly.Load has several overloads that all correspond to the same managed method, the unmanaged functions they call vary quite drastically.  Through this process, I attempted to deter