server/encoders/shellcode/sgn

Overview

SGN (Shikata Ga Nai) coordination and helpers. Implements SGN enrollment, messaging, and policy logic.

Go Files

sgn.go – Implements SGN coordination logic and message handling, including the Shikata Ga Nai encoder helpers.
sgn_test.go – Unit tests covering SGN configuration wiring and helper utilities.

SGN Encoder Helpers

The server helper wraps the github.com/moloch--/sgn encoder and exposes a simple SGNConfig with the following knobs:

Architecture – 386/amd64 (case-insensitive) selection passed to sgn.NewEncoder.
Iterations – number of encode passes mapped to Encoder.EncodingCount.
MaxObfuscation – byte budget forwarded to Encoder.ObfuscationLimit.
PlainDecoder – keep the decoder stub in clear text.
Safe – enable register preservation via Encoder.SaveRegisters.
BadChars / Asci – optional post-processing filters that brute force new seeds until constraints pass.

These options mirror the upstream CLI flags so server-side tasks can reuse the same behavior.

Test Fixtures

Shellcode fixtures used by the unit tests live under testdata/ with a .bin extension. They are produced via msfvenom using a dedicated Go generator:

bash

go generate ./server/encoders/shellcode/sgn

The generator invokes msfvenom three times (reverse TCP/HTTP stagers and an exec payload) and writes raw shellcode into the testdata directory. Ensure the Metasploit framework is installed and msfvenom is on $PATH before running the generation step.

Testing

The log subsystem expects a writable Sliver root directory. Point it to a temporary location when running tests:

bash

export SLIVER_ROOT_DIR=$(pwd)/.tmp-sliver
export GOCACHE=$(pwd)/.tmp-gocache
mkdir -p "$SLIVER_ROOT_DIR" "$GOCACHE"
go test ./server/encoders/shellcode/sgn

The test suite focuses on option wiring and constraint helpers rather than the full stochastic encoding pipeline.