[NEWS] AWStats Remote Command Execution Vulnerability (configdir)

From: SecuriTeam (support_at_securiteam.com)
Date: 01/18/05

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Date: 18 Jan 2005 11:37:58 +0200

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      AWStats Remote Command Execution Vulnerability (configdir)
    ------------------------------------------------------------------------

    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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