1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
# This plugin will attempt to resolve simple jump tables (an array of code pointers) and add the destinations
# as indirect branch targets so that the flow graph reflects the jump table's control flow.
from binaryninja import *
import struct
def find_jump_table(bv, addr):
for block in bv.get_basic_blocks_at(addr):
func = block.function
arch = func.arch
addrsize = arch.address_size
# Grab the instruction tokens so that we can look for the table's starting address
tokens, length = arch.get_instruction_text(bv.read(addr, 16), addr)
# Look for the next jump instruction, which may be the current instruction. Some jump tables will
# compute the address first then jump to the computed address as a separate instruction.
jump_addr = addr
while jump_addr < block.end:
info = arch.get_instruction_info(bv.read(jump_addr, 16), jump_addr)
if len(info.branches) != 0:
break
jump_addr += info.length
if jump_addr >= block.end:
print "Unable to find jump after instruction 0x%x" % addr
continue
print "Jump at 0x%x" % jump_addr
# Collect the branch targets for any tables referenced by the clicked instruction
branches = []
for token in tokens:
if token.type == "PossibleAddressToken": # Table addresses will be a "possible address" token
tbl = token.value
print "Found possible table at 0x%x" % tbl
i = 0
while True:
# Read the next pointer from the table
data = bv.read(tbl + (i * addrsize), addrsize)
if len(data) == addrsize:
if addrsize == 4:
ptr = struct.unpack("<I", data)[0]
else:
ptr = struct.unpack("<Q", data)[0]
# If the pointer is within the binary, add it as a destination and continue
# to the next entry
if (ptr >= bv.start) and (ptr < bv.end):
print "Found destination 0x%x" % ptr
branches.append((arch, ptr))
else:
# Once a value that is not a pointer is encountered, the jump table is ended
break
else:
# Reading invalid memory
break
i += 1
# Set the indirect branch targets on the jump instruction to be the list of targets discovered
func.set_user_indirect_branches(arch, jump_addr, branches)
# Create a plugin command so that the user can right click on an instruction referencing a jump table and
# invoke the command
PluginCommand.register_for_address("Process jump table", "Look for jump table destinations", find_jump_table)
|
