Vigil@nce: GNOME Display Manager, reading password
July 2010 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/
SYNTHESIS OF THE VULNERABILITY
When a GNOME Display Manager user entered a password containing a
special character, it is displayed in a log file.
– Severity: 1/4
– Creation date: 29/07/2010
DESCRIPTION OF THE VULNERABILITY
The gdmlogin process of GNOME Display Manager receives the login
and the password entered by the user.
The ve_locale_from_utf8() function decodes UTF-8 stirngs. If a
string contains an invalid character, an error message is
displayed:
string not in proper utf8 encoding: here_the_string
This error message is displayed in the /var/log/messages log file,
which is readable by all users.
When the user inadvertently enters a special character in his
password, the log file thus contains this wrong password (in most
cases, it is similar to the real password).
When a GNOME Display Manager user entered a password containing a
special character, a local attacker can therefore read the log
file, and then guess the password.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
http://vigilance.fr/vulnerability/GNOME-Display-Manager-reading-password-9795