Kmem security (was: Re: How do you make your UNIX crash ???)

[Magnus Olsson]

In article <9103152251.41 at rmkhome.UUCP> rmk at rmkhome.UUCP (Rick Kelly) writes:
>When anyone logs in, even root, login has to decrypt
>the password in /etc/password to compare it to the password typed it.  This
>password in memory lays around for a while.  It is extremely easy to grab
>passwords out of kmem, and match them to ANY user, including root.

Sorry, but this is bogus.

login does *not* have to decrypt the password from /etc/passwd - indeed,
I don't think there's any way it could do that! (The encryption function
is not invertible - several different passwords acan have the same
encrypted from). Instead, it encrypts the typed-in password and compares
it to the one in /etc/passwd.

That doesn't mean, of course, that you can't get passwords from /dev/kmem -
login has to keep the entered password somewhere before it encrypts it!


Magnus Olsson                   | \e+      /_
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