Quais são as implicações de segurança se uma senha é enviada no campo Nome de usuário?

Let’s say I typed my password into the username text box of a frequently-visited website (https of course) and hit enter before I noticed what I was doing.

Is my password now sitting in plain text in a log file somewhere? How could my mistake be exploited by a crafty miscreant? Help me understand the actual security implications regardless of the likelihood of it actually happening.

It depends on the configuration of the authentication system for the website. If it was setup to log any attempts, then yes, it is now in the log (text file or database) in plain text. It could look like this:

12-Feb-2014 12:00:00 AM: Unsuccessful login attempt user (YOUR_PASSSORD_HERE) from (YOUR_IP_HERE);

or similar.

It is still true that a password will not be accessible for regular users, only for those who have access to log files.

What consequences does it imply?

• If the server was ever compromised, then theoretically, the hacker would have your plain text password.
• The website’s administrator could routinely go through the log files and accidentally find your password. He can then find the IP address this record came from, and thus he can theoretically find out what your username and e-mail are (because he has access to the database).

So, if you use the same e-mail/username/password on other websites, then change it immediately. Because there is always a chance that your password will be found out. Logs can remain on servers for years.

Just as you said, web applications tend to keep logs of unsuccessful login attempts. If someone were to look through the logs, he could connect this particular login attempt with one of your successful attempts (i.e. via IP address).

Though I do not think this is likely to happen, you can always change it be sure.