~ftp/etc/passwd Vulnerability
Summary
An anonymous FTP password file that contains encrypted password fields
can be used in a password cracking program to find user passwords.
An anonymous FTP password file that has a high number of user uids can
provide a system crackers with information that can be useful in attacking
a system.
Impact
Unauthorized user access to system.
Background
The password file used in an anonymous FTP area is used by the ls(1)
program to show usernames and group names associated with files.
FTP administrators sometimes copy the real system passwd file for
use by in FTP area.
The problem
If the system does not have a shadow password system and the administrator
just copies the /etc/passwd file, then the encrypted passwords and all the
usernames are available to the world. There are widely programs available to
attempt to crack passwords using a dictionary attack method. System crackers
can also use the information in the GECOS field of the passwd file
to make educated guesses at the users' passwords. The GECOS field is
can contain information about the user such as office location, phone
numbers, and the user's full name.
Fix
See Also