expand_path is not implemented consistently across platforms and
sessions, which leads to confusing behavior. In places where we have trivial
single variable expansions, this changes modules and library code to just use
getenv.
We'll look at the rest individually to see if they can also be reimplemented in
terms of getenv.
Add Exploit::Powershell::DotNet namespace with compiler and
runtime elevator.
Add compiler modules for payloads and custom .NET code/blocks.
==============
Powershell-based persistence module to compile .NET templates
with MSF payloads into binaries which persist on host.
Templates by @hostess (way back in 2012).
C# templates for simple binaries and a service executable with
its own install wrapper.
==============
Generic .NET compiler post module
Compiles .NET source code to binary on compromised hosts.
Useful for home-grown APT deployment, decoy creation, and other
misdirection or collection activities.
Using mimikatz (kiwi), one can also extract host-resident certs
and use them to sign the generated binary, thus creating a
locally trusted exe which helps with certain defensive measures.
==============
Concept:
Microsoft has graciously included a compiler in every modern
version of Windows. Although executables which can be easily
invoked by the user may not be present on all hosts, the
shared runtime of .NET and Powershell exposes this functionality
to all users with access to Powershell.
This commit provides a way to execute the compiler entirely in
memory, seeking to avoid disk access and the associated forensic
and defensive measures. Resulting .NET assemblies can be run
from memory, or written to disk (with the option of signing
them using a pfx cert on the host). Two basic modules are
provided to showcase the functionality and execution pipeline.
Usage notes:
Binaries generated this way are dynamic by nature and avoid sig
based detection. Heuristics, sandboxing, and other isolation
mechanisms must be defeated by the user for now. Play with
compiler options, included libraries, and runtime environments
for maximum entropy before you hit the temmplates.
Defenders should watch for:
Using this in conjunction with WMI/PS remoting or other MSFT
native distributed execution mechanism can bring malware labs
to their knees with properly crafted templates.
The powershell code to generate the binaries also provides a
convenient method to leave behind complex trojans which are not
yet in binary form, nor will they be until execution (which can
occur strictly in memory avoiding disk access for the final
product).
==============
On responsible disclosure: I've received some heat over the years
for prior work in this arena. Everything here is already public,
and has been in closed PRs in the R7 repo for years. The bad guys
have had this for a while (they do their homework religiously),
defenders need to be made aware of this approach and prepare
themselves to deal with it.
adfoster-r7