Class: Rex::Exploitation::RopDb

Inherits:
Object
  • Object
show all
Defined in:
lib/rex/exploitation/ropdb.rb

Overview

This class provides methods to access the ROP database, in order to generate a ROP-compatible payload on the fly.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ RopDb

Returns a new instance of RopDb.



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# File 'lib/rex/exploitation/ropdb.rb', line 16

def initialize
  @base_path = File.join(File.dirname(__FILE__), '../../../data/ropdb/')
end

Instance Method Details

#generate_rop_payload(rop, payload, opts = {}) ⇒ Object

Returns a payload with the user-supplied stack-pivot, a ROP chain, and then shellcode. Arguments: rop - Name of the ROP chain payload - Payload in binary opts - A hash of optional arguments:

'nop'      - Used to generate nops with generate_sled()
'badchars' - Used in a junk gadget
'pivot'    - Stack pivot in binary
'target'   - A regex string search against the compatibility list.
'base'     - Specify a different base for the ROP gadgets.

Raises:

  • (RuntimeError) 


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# File 'lib/rex/exploitation/ropdb.rb', line 78

def generate_rop_payload(rop, payload, opts={})
  nop      = opts['nop']      || nil
  badchars = opts['badchars'] || ''
  pivot    = opts['pivot']    || ''
  target   = opts['target']   || ''
  base     = opts['base']     || nil

  rop = select_rop(rop, {'target'=>target, 'base'=>base})
  # Replace the reserved words with actual gadgets
  rop = rop.map {|e|
    if e == :nop
      sled = (nop) ? nop.generate_sled(4, badchars).unpack("V*")[0] : 0x90909090
    elsif e == :junk
      Rex::Text.rand_text(4, badchars).unpack("V")[0].to_i
    elsif e == :size
      payload.length
    elsif e == :unsafe_negate_size
      get_unsafe_size(payload.length)
    elsif e == :safe_negate_size
      get_safe_size(payload.length)
    else
      e
    end
  }.pack("V*")

  raise RuntimeError, "No ROP chain generated successfully" if rop.empty?

  return pivot + rop + payload
end

#has_rop?(rop_name) ⇒ Boolean

Returns true if a ROP chain is available, otherwise false

Returns:

  • (Boolean) 


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# File 'lib/rex/exploitation/ropdb.rb', line 26

def has_rop?(rop_name)
  File.exist?(File.join(@base_path, "#{rop_name}.xml"))
end

#select_rop(rop, opts = {}) ⇒ Object

Returns an array of ROP gadgets. Each gadget can either be an offset, or a value (symbol or some integer). When the value is a symbol, it can be one of these: :nop, :junk, :size, :unsafe_negate_size, and :safe_negate_size Note if no RoP is found, it returns an empry array. Arguments: rop_name - name of the ROP chain. opts - A hash of optional arguments:

'target' - A regex string search against the compatibility list.
'base'   - Specify a different base for the ROP gadgets.

Raises:

  • (RuntimeError) 


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# File 'lib/rex/exploitation/ropdb.rb', line 41

def select_rop(rop, opts={})
  target = opts['target'] || ''
  base   = opts['base']   || nil

  raise RuntimeError, "#{rop} ROP chain is not available" if not has_rop?(rop)
  xml = load_rop(File.join(@base_path, "#{rop}.xml"))

  gadgets = []

  xml.elements.each("db/rop") { |e|
    name = e.attributes['name']
    next if not has_target?(e, target)

    if not base
      default = e.elements['gadgets'].attributes['base'].scan(/^0x([0-9a-f]+)$/i).flatten[0]
      base = default.to_i(16)
    end

    gadgets << parse_gadgets(e, base)
  }
  return gadgets.flatten
end