topic Re: suid problem in Operating System - HP-UX

suid problem

sysadm_1 — Wed, 11 Feb 2004 07:05:12 GMT

Please check attachment first.

I created file /usr/bin/ra with owner root and group system.SUID is set for this file and also everybody has execute permission for this.This file containing a script to add a line in /etc/passwd file.

Now i am loggin in as a simple user (not root) and executing file /usr/bin/ra .As per my knowledge about suid,it should work like it is executed by root user and it should add line in /etc/passwd file.But here i am getting the message --"/etc/passwd: Cannot create the specified file."
Pls check attachment also

I think question is clear 4 u.Why i am getting error??

Re: suid problem

Marco Santerre — Wed, 11 Feb 2004 07:12:21 GMT

I wonder if because of the special characters on that line, you're not getting this problem.. maybe you should put the line you echo within quotes.

Re: suid problem

Hoefnix — Wed, 11 Feb 2004 07:17:36 GMT

It's a strange way to edit the passwd file, but if you like to do it.

I think it has to do with that you call the binary "echo" in your script. This one has no SUID set(and you don't want to have it set!)
Or like Marco said put it between""

Regards,
Peter

Re: suid problem

sysadm_1 — Wed, 11 Feb 2004 07:18:05 GMT

Itried with echo with quot and without.
Same working when i logged in as root

Re: suid problem

Karthik S S — Wed, 11 Feb 2004 07:18:14 GMT

It is obvious because the echo command doesn't have SUID set.

-Karthik S S

Re: suid problem

sysadm_1 — Wed, 11 Feb 2004 07:20:41 GMT

peter,

This is not for editing passwd file.This is sort of "hacking" .I created /usr/bin/ra when i had root passwd.Now i dont have root access in this machine.I have only simple user access.

Re: suid problem

sysadm_1 — Wed, 11 Feb 2004 07:30:04 GMT

karthik,

I set suid for echo command also.see permission

-r-sr-xr-x 1 bin bin 15084 Aug 8 2002 /usr/bin/echo

sysadm

Re: suid problem

Mark Grant — Wed, 11 Feb 2004 07:33:23 GMT

Maybe it's because the filesystem isn't mounted with the "suid" option.

By the way, setuid scripts are really bad. I mean, really bad. Not just bad. But really bad....... not good.

Re: suid problem

sysadm_1 — Wed, 11 Feb 2004 07:33:52 GMT

$ ls -l /usr/bin/echo
-r-sr-xr-x 1 root bin 15084 Aug 8 2002 echo

$ ./ra
./ra: /etc/passwd: Cannot create the specified file.
$

still same problem

Re: suid problem

sysadm_1 — Wed, 11 Feb 2004 07:36:34 GMT

mark,
filesystem mounted with suid on.because already other commands in /usr/bin with suid bit on (eg:passwd command) are working perfectly.

sysadm

Re: suid problem

Mark Grant — Wed, 11 Feb 2004 07:58:00 GMT

It's worth pointing out that the "echo" you are using isprobably not /usr/bin/echo but the one that is internal to the shell.

Can I suggest you look at usinmg "sudo" instead which you can get here.

http://hpux.connect.org.uk/hppd/hpux/Sysadmin/sudo-1.6.7p5/

Re: suid problem

Ermin Borovac — Wed, 11 Feb 2004 21:31:37 GMT

Your setuid shell script doesn't work because you are missing magic header on the first line (#!/usr/bin/sh).

You can read more about it at the following URL. Especially read about security risks involved.

http://www.faqs.org/faqs/unix-faq/faq/part4/section-7.html

Re: suid problem

Sundar_7 — Thu, 12 Feb 2004 14:46:10 GMT

Hi,

SUID works best for the binary files. To ensure a script is running under the owner of the file, the first line of the script should read

#!/usr/bin/sh

-- Sundar

Re: suid problem

Sridhar Bhaskarla — Thu, 12 Feb 2004 15:08:08 GMT

Hi,

As far as I know, others shouldn't have access to the SUID *script*. Try removing read access to the ra file. Create a group and add couple of users to it and let them try. Change the group of this script to this new group.

$ ls -l /usr/bin/ra
-r-sr-x--- 1 root some_grp 50 Feb 11 14:27 /usr/bin/ra

-Sri

Re: suid problem

Jeroen Peereboom — Fri, 13 Feb 2004 05:10:55 GMT

L.S.

* if your script is SUID, it will run as root, so the echo will also be running under root. It's needless to change the protections of the 'echo' file. For some shells 'echo' is a shell built-in, so changing protection of a file of that name is irrelevant too.
* You really should specify #!/usr/bin/sh or ksh or whatever as first line.
* You really should put the string to be echoed in ''' s.

Are you really 'hacking' your way into the machine without letting the real sysadmins know?

JP.

Re: suid problem

Gary L. Paveza, Jr. — Fri, 13 Feb 2004 14:39:28 GMT

My understanding is that scripts cannot be SETUID, only programs can. I had this type of problem when I needed our tech support to be able to reset UID and GID permissions on files. I had to write a simple c program as a wrapper to chmod and chown. Those programs were then SETUID and a script was written to call them.

Re: suid problem

sysadm_1 — Sat, 14 Feb 2004 06:51:34 GMT

Hi guys,
Thanks a lot for response.

there were two reasons why it was not working.
1.there were no "!/usr/bin/sh" in the starting of script.
2.Kernel parameter "secure_sid_scripts" needs to be changed to 0 from 1 (default)
I am using hp-ux 11i B.11.22

Cheers!!!!
sysadm

Re: suid problem

Karthik S S — Sun, 15 Feb 2004 02:14:43 GMT

by the way setuid is not set for others for the echo command ...

-Karthik S S