Piece of code to find null passwords from /etc/shadow

[Senthil Prabu.S_1]

Hello Guru,
I am looking for piece code which helps me to find the list of users with null password [exluding accounts that are locked] on my unix machine with /etc/shadow file. It can be either in C or perl script.....

I got a piece of perl script from perl-doc which works for root user.

$pwd = (getpwuid($<))[1];
$word="";# this is null as checking for null password.
$password=crypt($word, $pwd);

But I don't know how to make use of getpwuid() to find other existing users .
Can anyone please help me to validate null passwords.

Note:
I dont want to block null-passwords, all I want is to find a list of users with weak passwords, mainly null password.

With Advance Thanks,
Prabu.S

[Peter Godron]

Prabu,
would this not be a security risk to have/run this script ?

I would change the secrity policy, which would lock the account.

You could then use
/usr/lbin/getprpw -m lockout
Which should give to lockout reason:
0 acount enabled
1 in position
1 - password lifetime expired
2 - inactive account
3 - account time disabled
4 - too many login attempts
5 - password required and a null password
6 - admin locked it
7 - * password

[Senthil Prabu.S_1]

Hi Peter,
As part of security measure, I need to do this, not a security issue at all. Once I get the list of users, later I will progress either to lock the user or to raise alarms.... So all I need is to find list of null password...

Hope now you understood my requirement....

Also I need to do this on sun10 OS, I cannot find getprpw utility on solaris box...


Prabu.S

[Peter Godron]

Prabu,
sorry didn't realise it was Solaris.

Have you looked at:
http://perldoc.perl.org/functions/getpwuid.html
and
http://www.die.net/doc/linux/man/man3/getpwuid.3.html

[Ralph Grothe]

Hi Prabu,

a "perldoc -f getpwuid" will show you what the getpw* implementations of the namesake C syscalls return in either scalar or list context.
To cycle through all of your box'es accounts one probably would use a getpwent in a while loop.

e.g.

to simply print out accounts that assigned themselves an empty password, you could loop like this

while (my @rec = getpwent) {
print "$rec[0]\n" if (crypt("", substr($rec[1],0,2)) eq $rec[1]);
}


Better yet, you implement a password regime where no one is allowed to get away with empty passwords ;-)

[Todd Goldsmith]

Check if you have the logins command. The following command on HP-UX will list all users with no password:

logins -p

Another very useful feature:

logins -d

shows users that have the same UID -- very useful to expose a hacker that created another root login.

[Senthil Prabu.S_1]

Hi Todd,
My problem is that when a user tries to set empty password, he types return key alos, so "\n" is considered as password, which is later crypted and stored in /etc/shadow, practically there is a password set, that is "\n", which I should be able to get, logins will not help me to solve this problem.

Hope you understand my problem,

Thanks,
Prabu.S

[Court Campbell]

well if the passwd command in solaris is anything like the hp-ux version you should be able to use the command

#passwd -s username


If you see an NP in the output that means that there is no password.

[Senthil Prabu.S_1]

Got the solution, so closing it.