Daily Archives: 2012-01-06

Brute force password-guessing attempts on SSH

I recently set up a server, and predictably it started seeing brute-force password-guessing attempts on SSH. The host only permits public key authentication, and I also used fail2ban to temporarily block repeat offenders and so stop my logs from being filled up. However, I was curious what attackers were actually doing, so I patched OpenSSH to log the username and password for log-in attempts to invalid users (i.e. all except my user-account).

Some of the password attempts are predictable (e.g. username: “root”, password: “root”) but others are less easy to explain. For example, there was a log-in attempt for the usernames “root” and “dark” with the password “ManualulIngineruluiMecanic”, which I think is Romanian for Handbook of Mechanical Engineering. Why would someone use this password, especially for the uncommon username “dark”? Is this book common in Romania; is it likely to be by the desk of a sys-admin (or hacker) trying to choose a password? Has the hacker found the password in use on another compromised system; is it the default password for anything?

Over the next few weeks I’ll be posting other odd log-in attempts on my Twitter feed. Follow me if you would like to see what I find. Feel free to comment here if you have any theories on why these log-in attempts are being seen.