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AWStats Remote Command Execution Vulnerability (configdir)
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SUMMARY
<http://awstats.sourceforge.net> AWStats is "a free tool that generates
advanced web, ftp or mail server statistics, graphically". Remote
exploitation of an input validation vulnerability in AWStats allows
attackers to execute arbitrary commands under the privileges of the web
server.
DETAILS
Vulnerable Systems:
* AWStats version 6.1 and prior
Immune Systems:
* AWStats version 6.3 or newer
The problem specifically exists when the application is running as a CGI
script on a web server. The "configdir" parameter contains
unfiltered user-supplied data that is utilized in a call to the Perl
routine open() as can be seen here on line 1082 of awstats.pl:
if (open(CONFIG,"$searchdir$PROG.$SiteConfig.conf"))
The "searchdir" variables hold the value of the parameter provided by the
attacker from "configdir." An attacker can cause arbitrary commands to be
executed by prefixing them with the "|" character.
Analysis:
Successful exploitation allows remote attackers to execute arbitrary
commands under the privileges of the web server. This can lead to further
compromise as it provides remote attackers with local access.
Workaround:
Add a filter around the "configdir" parameter by replacing the following
line:
if ($QueryString =~ /configdir=([^&]+)/i)
{
$DirConfig=&DecodeEncodedString("$1");
}
With:
if ($QueryString =~ /configdir=([^&]+)/i)
{
$DirConfig=&DecodeEncodedString("$1");
$DirConfig=~tr/a-z0-9_\-\/\./a-z0-9_\-\/\./cd;
}
Vendor response:
This vulnerability is addressed in AWStats 6.3, available for download at:
<http://awstats.sourceforge.net/#DOWNLOAD>
http://awstats.sourceforge.net/#DOWNLOAD
Exploit:
The following URL will create a file named 'id' in the tmp directory of
the remote server with the content of the command /usr/bin/id:
http://vulnerable/cgi-bin/awstats.pl?configdir=/usr/bin/id%20%3E%20/tmp/id%20|%20
Disclosure timeline:
10/21/2004 - Initial vendor notification
01/02/2005 - Initial vendor response
01/17/2005 - Public disclosure
ADDITIONAL INFORMATION
The information has been provided by
<mailto:idlabs-advisories@idefense.com> iDEFENSE. The exploit has been
provided by <mailto:expert@securiteam.com> Noam Rathaus of Beyond
Security Ltd.
The original article can be found at:
<http://www.idefense.com/application/poi/display?id=185&type=vulnerabilities>
http://www.idefense.com/application/poi/display?id=185&type=vulnerabilities
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