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                                            NimlineWhispers2
                                            @ajpc500 2021

NimlineWhispers2

Originally inspired by Outflank's InlineWhispers tool, NimlineWhispers2 processes output from SysWhispers2 to provide compatible inline assembly for use in Nim projects.

As with the original NimlineWhispers, this project also parses the SysWhispers2 header file output to include function return types and arguments in the outputted inline assembly. Everything is then output into a single Nim file including an emit block with the SysWhispers2 methods, plus the defined functions.

NOTE: NimlineWhispers 1 can be found here.

How do I set this up?

• Clone this repository including the forked SysWhispers2 sub module.
  • git clone --recurse-submodules https://github.com/ajpc500/NimlineWhispers2.git
• Update which functions you required in functions.txt.
• Run python3 NimlineWhispers2.py (additional flags listed below) to generate the inline assembly (syscalls.nim) file - example in the repo.
• Add include syscalls to your Nim project.

An example of integrating NimlineWhispers2 output with your project can be seen in this repo.

Randomised Function Names (same functionality as NW1)

To evade detection based on the presence of function names in our Nim executables (as outlined in @ShitSecure's blog here), NimlineWhispers2 can be run with a --randomise flag, as follows:

python3 .\NimlineWhispers2.py --randomise --nobanner
[i] Function filter file "functions.txt" contains 6 functions.

[i] Using SysWhispers2 to generate asm stubs...
Complete! Files written to:
        nimlinewhispers.h
        nimlinewhispers.c
        nimlinewhispersstubs.asm

[i] Found return types for 6 functions.

[i] Producing randomised function mapping...
        NtResumeThread -> vWhUCQWffAEdMboE
        NtAllocateVirtualMemory -> SIitcDuyPGMirHPr
        NtClose -> uWZzTmdnlNmvteiL
        NtCreateThreadEx -> PDoWbNOwYbDDAcmW
        NtOpenProcess -> vWfwKlChxKZOutiX
        NtWriteVirtualMemory -> wItyVDPJWcFUqTNK

[+] Success! Outputted to syscalls.nim

For ease of integration, the mapping shown in the command-line is added as a comment in the outputted syscalls.nim file (just above the functions and below the SW2 methods). As below (including the first function to demonstrate the output):

...

# NtResumeThread -> vWhUCQWffAEdMboE
# NtAllocateVirtualMemory -> SIitcDuyPGMirHPr
# NtClose -> uWZzTmdnlNmvteiL
# NtCreateThreadEx -> PDoWbNOwYbDDAcmW
# NtOpenProcess -> vWfwKlChxKZOutiX
# NtWriteVirtualMemory -> wItyVDPJWcFUqTNK

proc vWhUCQWffAEdMboE*(ThreadHandle: HANDLE, PreviousSuspendCount: PULONG): NTSTATUS {.asmNoStackFrame.} =
    asm """
	mov [rsp +8], rcx 
...

Notably your function definitions such as the below will need to be updated with the randomised names too.

EXTERN_C NTSTATUS NtOpenProcess(
	OUT PHANDLE ProcessHandle,
	IN ACCESS_MASK DesiredAccess,
	IN POBJECT_ATTRIBUTES ObjectAttributes,
	IN PCLIENT_ID ClientId OPTIONAL);

Should become:

EXTERN_C NTSTATUS sjGfpzWwEqIMryMW(
	OUT PHANDLE ProcessHandle,
	IN ACCESS_MASK DesiredAccess,
	IN POBJECT_ATTRIBUTES ObjectAttributes,
	IN PCLIENT_ID ClientId OPTIONAL);

syscalls_rand.nim is included as an example output of this randomisation function.

Limitations

• 64-bit only.

Credits

• Cas van Cooten and yamakadi for posing and then answering how SW2 output could be used in Nim projects, which I've simply codified😁
• This tool uses SysWhispers2 to generate syscall stubs which are then processed for Nim, huge props to @Jackson_T for SysWhispers2.
• FalconForce's SysWhispers2BOF from which I borrowed several helper functions.
• All people credited for SysWhispers and SysWhispers2
• @Outflank and @_DaWouw for InlineWhispers
• @byt3bl33d3r for his incredibly informative OffensiveNim repository