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SMTP

Simple Mail Transfer Protocol

Check if sender could be forged with an domain user:

$ telnet mail.example.com 25
HELO example.com
MAIL FROM: <forged@example.com>
RCPT TO: <exists@example.com>
RCPT TO: <exists@gmail.com>

Check if sender could be forged with a non-domain user:

$ telnet mail.example.com 25
HELO example.com
MAIL FROM: <forged@gmail.com>
RCPT TO: <exists@example.com>
RCPT TO: <exists@gmail.com>

Check if domain users could be enumerated with VRFY and EXPN:

$ telnet mail.example.com 25
HELO example.com
VRFY exists@example.com
EXPN exists@example.com

Check if users could be enumerated with RCPT TO:

$ telnet mail.example.com 25
HELO example.com
MAIL FROM: <...>
RCPT TO: <exists@example.com>
DATA
From: <...>
To: <exists@example.com>
Subject: Job offer
Hello, I would like to offer you a great job!
.
QUIT

RCPT

smtp-enum

$ ./main.py -d megacorp.com -s 10.10.13.37 -f accounts.txt -m rcptto -o valid.txt

smtp-user-enum

$ smtp-user-enum -M RCPT -f '<root@megacorp.local>' -u '<j.doe@megacorp.com>' -t mx.megacorp.com
$ smtp-user-enum -M RCPT -D megacorp.com -U users.txt -t mx.megacorp.com

SPF/DKIM/DMARC

Tools

swaks

$ swaks --to j.doe@megacorp.com --from snovvcrash@megacorp.com --header 'Subject: Hello, friend' --body 'Hack the Planet!' --server 192.168.1.11 --attach hello.doc

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