POP3 (Port 110, 25*)

Quick Intro

Post Office Protocol (POP) is a type of computer networking and Internet standard protocol that extracts and retrieves email from a remote mail server for access by the host machine. POP is an application layer protocol in the OSI model that provides end users the ability to fetch and receive email .

The POP clients generally connect, retrieve all messages, store them on the client system, and delete them from the server. There are 3 versions of POP, but POP3 is the most used one.

Connection

telnet $ip 110

Banner Grabbing

nc -nv <IP> 110

openssl s_client -connect <IP>:995 -crlf -quiet

Manual

You can use the command CAPA to obtain the capabilities of the POP3 server.

Automated

nmap --script "pop3-capabilities or pop3-ntlm-info" -sV -port <PORT> <IP> #All are default scripts

The pop3-ntlm-info plugin will return some "sensitive" data (Windows versions).

Command

POP commands:
  USER uid           Log in as "uid"
  PASS password      Substitue "password" for your actual password
  STAT               List number of messages, total mailbox size
  LIST               List messages and sizes
  RETR n             Show message n
  DELE n             Mark message n for deletion
  RSET               Undo any changes
  QUIT               Logout (expunges messages if no RSET)
  TOP msg n          Show first n lines of message number msg
  CAPA               Get capabilities

Example

root@kali:~# telnet $ip 110
 +OK beta POP3 server (JAMES POP3 Server 2.3.2) ready 
 USER billydean    
 +OK
 PASS password
 +OK Welcome billydean

 list

 +OK 2 1807
 1 786
 2 1021

 retr 1

 +OK Message follows
 From: [e-mail]
 Dear Billy Dean,

 Here is your login for remote desktop ... try not to forget it this time!
 username: billydean
 password: PA$$W0RD!Z