[312] in linux-security and linux-alert archive
Re: chfn problem with Linux
daemon@ATHENA.MIT.EDU (Jon Lewis)
Wed Aug 9 04:25:14 1995
Date: Tue, 8 Aug 1995 16:02:33 -0400 (EDT)
From: Jon Lewis <jlewis@inorganic5.chem.ufl.edu>
To: Nick Kralevich <nickkral@parker.EECS.Berkeley.EDU>
cc: linux-alert@tarsier.cv.nrao.edu, linux-security@tarsier.cv.nrao.edu
In-Reply-To: <Pine.HPP.3.91.950808081744.21796A-100000@parker.EECS.Berkeley.EDU>
[mod: Does anyone have a passwd version for which the ulimit hack actually
works? I checked util-linux-1.5 and 2.2, which do bomb out with
an unchecked passwd. --okir]
On Tue, 8 Aug 1995, Nick Kralevich wrote:
> Here's another bad one.
>
> Set file limit to 0.
> run passwd and try to change passwd
>
> /etc/passwd is empty, and all logins are denied with "Login
> incorrect", i.e. one doesn't know what is wrong.
>
> By setting file limits low can partially truncate /etc/passwd.
Maybe I did something wrong, or maybe shadow is smarter, but doing this
did not damage the /etc/shadow or /etc/passwd on a shadowed Linux system.
luke:/var/homes/admin/jlewis$ ulimit -f 0
luke:/var/homes/admin/jlewis$ ulimit -f
0
luke:/var/homes/admin/jlewis$ passwd
Changing password for jlewis
Old Password:
Enter the new password (minimum of 5 characters)
Please use a combination of upper and lower case letters and numbers.
New Password:
Re-enter new password:
luke:/var/homes/admin/jlewis$ ls -l /etc/passwd
-rw-r--r-- 1 root root 1099 Aug 8 12:18 /etc/passwd
luke:/var/homes/admin/jlewis$ ls -l /etc/shadow
-rw-r----- 1 root shadow 829 Aug 8 15:39 /etc/shadow
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