rt-sa-2005-011.txt

` Advisory: Pico Server (pServ) Information Disclosure Of CGI Sources  
  
RedTeam found a Information Disclosure vulnerability in Pico Server (pServ)  
which gives an attacker the ability to read all files from cgi-bin.  
  
Details  
=======  
  
Product: Pico Server (pServ)  
Affected Version: 3.2(verified), <=3.2 probably too  
Immune Version: 3.3  
OS affected: all  
Security-Risk: medium  
Remote-Exploit: yes  
Vendor-URL: http://pserv.sourceforge.net/  
Vendor-Status: new version available  
Advisory-URL: http://tsyklon.informatik.rwth-aachen.de/redteam/rt-sa-2005-011  
Advisory-Status: published  
CVE: CAN-2005-1366  
(http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-1366 #)  
  
  
Introduction  
============  
  
>From http://pserv.sourceforge.net/  
Pico Server is a small web server. It is meant to be portable and  
configurable.  
  
* small, portable  
* fast  
* CGI-BIN support  
* auto-indexing of directories  
* access and error logging (see p-reporter for an analyzer)  
* forking or single-connection at choice  
  
Pico Server (pServ) is written in portable C (K&R style so it can compile on  
older compilers too) and sports several options that by means of #define  
statements can customize the behavior, the performance and the feature set so  
to be able to fit better the the requisites.  
  
Pserv does not correctly check whether a user accesses a file in cgi-bin and  
gives away the source instead of executing it.  
  
More Details  
============  
  
pServ has CGI-BIN support. Only URLs beginning with "cgi-bin" are treated as  
cgi-scripts.  
pServ checks, whether a file is in cgi-bin by checking whether the beginning  
of the directory part of the url matches "cgi-bin". A user can circumvent  
this by asking for /somedir/../cgi-bin/ and therefore is able to retrieve the  
complete sourcecode of all scripts in cgi-bin.  
  
Proof of Concept  
================  
  
This url lets us download the source of test.pl instead of executing it.  
http://vuln-host:2000/somedir/../cgi-bin/test.pl  
  
Workaround  
==========  
  
n/a  
  
Fix  
===  
  
The Developers have released Version 3.3. This version should fix the  
problem. The changes have not been tested by RedTeam, yet.  
  
Security Risk  
=============  
  
The security risk is rated medium because a remote attacker can get source  
code that would otherwise not be available to him. This can help the attacker  
in further attacks. As many programmers put sensitive configuration  
parameters like database passwords in the source code this attack can be  
quite harmful.  
  
History  
=======  
  
2005-04-29 found  
2005-05-02 first attempt to inform developers  
2005-05-02 CAN-number assigned  
2005-05-04 second attempt to inform developers  
2005-05-16 new version released. Advisory published.  
  
RedTeam  
=======  
  
RedTeam is a penetration testing group working at the Laboratory for  
Dependable Distributed Systems at RWTH-Aachen University. You can find more  
Information on the RedTeam Project at  
http://tsyklon.informatik.rwth-aachen.de/redteam/  
  
`