Mail Servers
SMTP [Port 25]
SMTP stands for Simple Mail Transfer Protocol.
It is a TCP/IP protocol that’s used for sending emails.
In order to be able to send emails with SMTP we have to first have to know how mail transactions work:
SMTP sessions are initiated after the client opens a TCP/IP connection to the server and the server responds with a greeting (220)
The client sends a
HELO
orEHLO
with the clients identity (example:HELO hackertarget.com
which means "Hi I'm hackertarget.com")Now the client has to perform 3 steps each separated by a CRLF for a valid SMTP mail transaction:
Step 1:
MAIL
: This tells the server "Hey, we're starting a new email, reset your state". This is where the email "from" is specified.Step 2:
RCPT
: Tells the server where (who) we want to send the email too.Step 3:
DATA
: This is where the Subject and body of the email are set, and the client indicates the end of the mail data by a new line containing only ".". This tells the server that the client confirms the email and tells the server to process it and send it.
Banner Grab
User Enumeration
-M: EXPN, VRFY or RCPT
-U: File of usernames
Email Enumeration
IMAP [Port 143]
POP3 [Port 110]
Free Mail Server
hMailServer [Windows]
James 2.3.2 RCE
Exploit Link
Last updated