Mail servers often store very sensitive information. It is critical that organizations use strong password policies, so penetration testers need to perform brute force password auditing against them to check for weak passwords.
This recipe will show you how to launch dictionary attacks against POP3 servers with Nmap.
To launch a dictionary attack against POP3 with Nmap, enter the following command:
$ nmap -p110 --script pop3-brute <target>Any valid accounts will be listed under the script output section:
PORT STATE SERVICE
110/tcp open pop3
| pop3-brute: webmaster : abc123
|_acc1 : password
The pop3-brute script was submitted by Philip Pickering, and it performs brute force password auditing against POP3 servers. By default, this script uses the word lists /nselib/data/usernames.lst and /nselib/data/passwords.lst, but you can change this by configuring the brute library.
The arguments -p110 --script pop3-brute...