Re: [Full-Disclosure] /bin/rm file access vulnerability

[bkfsec]

Yeah, I think that someone mistook the new year for April 1st.
Seriously, we seem to be getting more crap like this.  Are people just 
bored? 

            -Barry

J�rg Eschke wrote:
Sure, a user with admin rights is able to access/delete every local
file, regardless of the specific filepermissions.
Your 'exploit' will work with e.g. /bin/cat as well.
But i can't see a vulnerability anyway.
Am i missunderstanding something ?
Am Do, den 30.12.2004 schrieb Lennart Hansen um 2:18:
 

/bin/rm file access vulnerability
Affected Products:
        /bin/rm (all versions, tested on FreeBSD and linux)
        (http://www.freebsd.org    http://www.kernel.org)
Author:
        Xenzeo (Ablazed, Ultralaser, Lennart A. Hansen)
        xenzeo at blackhat dot dk
/bin/rm is a program that removes the named file arguments on unix systems.
When /bin/rm is called it checks the file's permissions and the id of the user
trying to remove the file. If the user does not have the required permissions
to delete the file, /bin/rm will simply reject and exit.
However, it is possible for a person with admin rights (root) to 
delete _any_ file
on the system regardless of who has created it and what it's permissions are.

Proof of concepts:
$ touch /home/xenzeo/file
$ ls -l /home/xenzeo/file
-rw-r--r--  1 xenzeo none 0 Dec 30  2004 /home/xenzeo/file
$ id
uid=1000(xenzeo) gid=513(none) groups=513(none),545(users)
$ su -c 'rm -f /home/xenzeo/file'
$ ls -l /home/xenzeo/file
ls: file: No such file or directory
#!/usr/bin/perl
if ($#ARGV != 0) {
        die "usage: rm-exploit.pl file\r\n";
} else {
   $file = $ARGV[0];
   print "*** CMD: [ /bin/rm -f $file ]\r\n";
   print "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\n";
   if ($> == 0) {
      print "[-] EXECUTING CMD\r\n";
      system("/bin/rm -f $file");
      print "[-] DONE\r\n";
      print "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\n";
      exit();
   } else {
      print "[-] EXPLOIT FAILED\r\n";
      print "[-] YOU ARE NOT ROOT\r\n";
      print "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\n";
   }
}
Vender status:
        Neither FreeBSD nor Linux developers have been contacted yet!
-Xenzeo
   

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.netsys.com/full-disclosure-charter.html