SMTP Enumeration

SMTP Enumeration

Simple Mail Transfer Protocol has VRFY request asks the server to verify an email address, while EXPN asks the server for the membership of a mailing list. PORT 25

• Manual

  • nc -nv <ip> 25

  • VRFY <user> if user not exist in mail server , it give error

• Automated script

  <aside> 🐍 #!/usr/bin/python

  import socket import sys

  if len(sys.argv) != 3: print(f"Usage: {sys.argv[0]} <ip_address> <username_file>") sys.exit(0)

  #Read the IP address and file name from the command line arguments

  ip_address = sys.argv[1] filename = sys.argv[2]

  #Read usernames from the text file

  try: with open(filename, "r") as f: usernames = f.read().splitlines() except IOError: print(f"Error: Unable to read from file '{filename}'") sys.exit(1)

  #Create a Socket

  s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

  #Connect to the Server

  connect = s.connect((ip_address, 25))

  #Receive the banner

  banner = s.recv(1024)

  print(banner)

  #Loop through each username and VRFY

  for username in usernames: s.send(f'VRFY {username}\r\n') result = s.recv(1024)

   print(result)

  #Close the socket s.close()

  </aside>

• Send Mail on SMTP

  • telnet <ip> 25

  • Set sender’s email MAIL FROM: [e-mail]

  • Set recipient mail RCPT TO: [e-mail]

  • To write the message, type DATA and press ‘Enter’ DATA

  • On the first line type ‘SUBJECT: Your Subject’ and press ‘Enter’ twice SUBJECT: Your Subject

  • Continue typing your message like Hello, this is test message

  • Put a single period (.) on a line by itself and press ‘Enter’ to send your message. .

  • Close the connection QUIT

  Reference: https://www.shellhacks.com/send-email-smtp-server-command-line/