Now that we have a list of usernames and we know that SMTP is open, we need to see if
VRFY is enabled. This is extremely simple, all you do is telnet into port 25 and execute the command
VRFY followed by a word and hit enter. The great part about checking for usernames this way is that if
VRFY is enabled, something is wrong with the secure deployment practices, and if it is Internet facing, they are likely not monitoring it. Reduce the number of credential attack guesses in an online credential attack against an interface will reduce the chances of being caught. The simple commands to execute this are shown in the following figure:
We did not get a hit for smith, but perhaps others will confirm during this attack. ...