Simple ROP gadget finder in python

gadgetFinder.py

import sys
from capstone import *

if len(sys.argv) < 2:
	print 'Error: need file name argument'
	exit()

# Read binary input file into an array
fileName = sys.argv[1]
file = open(fileName, "rb")
byteArr = []

try:
    byte = file.read(1)
    while byte != '':
        byte = file.read(1)
        byteArr.append(byte)
finally:
    file.close()

# Find all potential gadgets (bytes before a c3 byte (return instruction)) and put them in an array
potentialGadgets = []

for gadgetSize in range(1, 12): # Try multiple gadget sizes (in bytes)
	for index, byte in enumerate(byteArr):
		if byte == '\xc3':
			potentialGadgets.append((byteArr[index - gadgetSize : index + 1], index - gadgetSize))

# Disassemble the gadgets with Capstone and output to a text file
outFile = open('potentialGadgets.txt', 'w')
md = Cs(CS_ARCH_X86, CS_MODE_32)
count = 0
for gadget in potentialGadgets:
	bytes = ''.join(gadget[0])
	offset = gadget[1]

	instructions = []
	for i in md.disasm(bytes, 0x0):
		instructions.append(i)
	# Only use gadgets that actually end with a ret
	if len(instructions) > 1 and instructions[len(instructions) - 1].mnemonic == 'ret':
		outFile.write('Offset 0x%s:\n' % format(offset+1, 'x'))
		for i in instructions:
			outFile.write('{} {}\t{}\n'.format(i.mnemonic, i.op_str, '('+''.join([format(c, 'x') for c in i.bytes])+')'))
		count += 1
		outFile.write('\n')

outFile.close()

print 'Found', count, 'gadgets.'