Class: Rex::ElfScan::Scanner::JmpRegScanner

Inherits:
Generic
  • Object
show all
Defined in:
lib/rex/elfscan/scanner.rb

Direct Known Subclasses

PopPopRetScanner, RegexScanner

Instance Attribute Summary

Attributes inherited from Generic

#elf, #regex

Instance Method Summary collapse

Methods inherited from Generic

#initialize, #scan

Constructor Details

This class inherits a constructor from Rex::ElfScan::Scanner::Generic

Instance Method Details

#_build_byte_list(base, regnums) ⇒ Object

build a list for regex of the possible bytes, based on a base byte and a list of register numbers..



65
66
67
 
# File 'lib/rex/elfscan/scanner.rb', line 65

def _build_byte_list(base, regnums)
	regnums.collect { |regnum| Regexp.escape((base | regnum).chr) }.join('')
end

#_parse_ret(data) ⇒ Object 



80
81
82
83
84
85
86
 
# File 'lib/rex/elfscan/scanner.rb', line 80

def _parse_ret(data)
	if data.length == 1
		return "ret"
	else
		return "retn 0x%04x" % data[1, 2].unpack('v')[0]
	end
end

#_ret_size(offset) ⇒ Object 



69
70
71
72
73
74
75
76
77
78
 
# File 'lib/rex/elfscan/scanner.rb', line 69

def _ret_size(offset)
	case elf.read(offset, 1)
		when "\xc3"
			return 1
		when "\xc2"
			return 3
	end

	raise "wtf"
end

#config(param) ⇒ Object 



44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
 
# File 'lib/rex/elfscan/scanner.rb', line 44

def config(param)
	regnums = param['args']

	# build a list of the call bytes
	calls  = _build_byte_list(0xd0, regnums - [4]) # note call esp's don't work..
	jmps   = _build_byte_list(0xe0, regnums)
	pushs1 = _build_byte_list(0x50, regnums)
	pushs2 = _build_byte_list(0xf0, regnums)

	regexstr = '('
	if !calls.empty?
		regexstr += "\xff[#{calls}]|"
	end

	regexstr += "\xff[#{jmps}]|([#{pushs1}]|\xff[#{pushs2}])(\xc3|\xc2..))"

	self.regex = Regexp.new(regexstr, nil, 'n')
end

#scan_segment(program_header, param = {}) ⇒ Object 



89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
 
# File 'lib/rex/elfscan/scanner.rb', line 89

def scan_segment(program_header, param={})
	offset = program_header.p_offset

	hits = []

	while (offset = elf.index(regex, offset)) != nil

		rva     = elf.offset_to_rva(offset)
		message = ''

		parse_ret = false

		byte1 = elf.read(offset, 1).unpack('C')[0]

		if byte1 == 0xff
			byte2   = elf.read(offset+1, 1).unpack('C')[0]
			regname = Rex::Arch::X86.reg_name32(byte2 & 0x7)

			case byte2 & 0xf8
			when 0xd0
				message = "call #{regname}"
				offset += 2
			when 0xe0
				message = "jmp #{regname}"
				offset += 2
			when 0xf0
				retsize = _ret_size(offset+2)
				message = "push #{regname}; " + _parse_ret(elf.read(offset+2, retsize))
				offset += 2 + retsize
			else
				raise "wtf"
			end
		else
			regname = Rex::Arch::X86.reg_name32(byte1 & 0x7)
			retsize = _ret_size(offset+1)
			message = "push #{regname}; " + _parse_ret(elf.read(offset+1, retsize))
			offset += 1 + retsize
		end

		hits << [ rva, message ]
	end

	return hits
end