Add RSpec coverage for Msf::Util::EXE.to_winaarch64pe

spec/lib/msf/util/exe/windows/aarch64_spec.rb

@@ -0,0 +1,51 @@
+# -*- coding: binary -*-
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Msf::Util::EXE::Windows::Aarch64 do
+  let(:template) do
+    File.expand_path('../../../../../../data/templates/template_aarch64_windows.exe', __dir__)
+  end
+
+  # The generator only tolerates payloads up to WINAARCH64_PAYLOAD_SPACE
+  # (currently 8192) bytes because that is the size of the fixed payload[]
+  # buffer compiled into template_aarch64_windows.exe. The oversize test uses
+  # 8193 bytes so any change to WINAARCH64_PAYLOAD_SPACE that widens the
+  # buffer will surface here.
+  let(:max_payload_space) { Msf::Util::EXE::Windows::Aarch64::ClassMethods::WINAARCH64_PAYLOAD_SPACE }
+
+  describe '.to_winaarch64pe' do
+    let(:payload) { 'A'.b * 32 }
+
+    let(:generated_exe) do
+      Msf::Util::EXE.to_winaarch64pe(nil, payload, template: template)
+    end
+
+    let(:template_bytes) { File.binread(template) }
+    let(:payload_offset) { template_bytes.index('PAYLOAD:') }
+
+    it 'returns a Windows PE the same size as the template' do
+      expect(generated_exe.bytesize).to eq(template_bytes.bytesize)
+      expect(generated_exe.byteslice(0, 2)).to eq('MZ')
+    end
+
+    it 'injects the shellcode at the PAYLOAD: tag offset' do
+      expect(payload_offset).not_to be_nil
+      expect(generated_exe.byteslice(payload_offset, payload.bytesize)).to eq(payload)
+    end
+
+    it 'leaves bytes before and after the payload buffer unchanged' do
+      expect(generated_exe.byteslice(0, payload_offset)).to eq(template_bytes.byteslice(0, payload_offset))
+
+      tail_offset = payload_offset + max_payload_space
+      expect(generated_exe.byteslice(tail_offset..)).to eq(template_bytes.byteslice(tail_offset..))
+    end
+
+    it 'raises when the payload exceeds the template payload buffer' do
+      oversized = 'B'.b * (max_payload_space + 1)
+      expect { Msf::Util::EXE.to_winaarch64pe(nil, oversized, template: template) }
+        .to raise_error(RuntimeError, /max size of #{max_payload_space} bytes/)
+    end
+  end
+end