suid problem

[sysadm_1]

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??

[Marco Santerre]

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.

[Hoefnix]

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

[sysadm_1]

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

[Karthik S S]

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

-Karthik S S

[sysadm_1]

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.

[sysadm_1]

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

[Mark Grant]

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.

[sysadm_1]

$ 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

[sysadm_1]

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

sysadm

[Mark Grant]

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/

[Ermin Borovac]

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

[Sundar_7]

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

[Sridhar Bhaskarla]

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

[Jeroen Peereboom · Accepted solution]

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.

[Gary L. Paveza, Jr.]

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.

[sysadm_1]

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

[Karthik S S]

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

-Karthik S S