blogtorrent.txt

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Intro  
-----  
  
Blogtorrent is a collection of PHP scripts which are designed to   
make it simple to host files for transfer via bittorrent.  
  
Whilst it is not normal to report security problems in "preview"  
releases of software this software was covered prominently upon   
Slashdot and could be widely used, so I feel it's a legitimate  
target.  
  
  
  
Problem  
-------  
  
One of the scripts in the distribution doesn't correctly  
sanitize it's inputs, before using one of them to read   
and serve a file from the local system.  
  
This can be exploited to remotely download any file upon the   
webserver which is readable by the UID which the webserver is  
running as.  
  
The code in question is contained in btdownload.php and looks like  
this:  
  
--  
echo file_get_contents('torrents/'.$_GET['file']);  
--  
  
  
  
Example  
-------  
  
The following URL can be used to download a file:  
  
  
htp://example.org/battletorrent/btdownload.php?type=torrent&file=../../etc/passwd  
  
(Adjust the ".."'s and the filename to suit your taste).  
  
  
Fix  
---  
  
Whilst no new release is planned to address this hole the  
authors did commit a simple fix to their CVS repository.  
  
This can be obtained from here:  
  
http://cvs.sourceforge.net/viewcvs.py/battletorrent/btorrent_server/btdownload.php?r1=1.6&r2=1.7  
  
(The patch was committed less than a day after the hole was privately  
reported to them, making them a responsive bunch).  
  
Steve  
--  
# The Debian Security Audit Project.  
http://www.debian.org/security/audit  
  
# Setuid Software Lists  
http://www.setuid.org/  
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