> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/web/authentication/brute-forcing-a-stay-logged-in-cookie.md).
# Brute Forcing a Persistent Session Cookie
Brute Forcing a Persistent Session Cookie notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Brute-forcing a Stay-logged-in Cookie
This lab allows users to stay connected even after they have closed their browsers. The cookie used for this feature is vulnerable to brute force. / To solve the lab, you need to brute-force Carlos' cookie to access its My account page.
**Provided credentials:** `wiener:peter`/ \*\* Name of victim:\*\* `carlos`
### \*\*Analysis of the Mechanism
When you check the automatic reconnection option, the following query is sent:
```bash
username=wiener&password=peter&stay-logged-in=on
```
The server then returns a cookie named **stay-logged-in**, whose content is encoded in Base64:
```bash
d2llbmVyOjUxZGMzMGRkYzQ3M2Q0M2E2MDExZTllYmJhNmNhNzcw
```
After decoding, we obtain:
```bash
wiener:51dc30ddc473d43a6011e9ebba6ca770
```
The cookie structure is therefore:
By checking the hash via CrackStation, we discover that it corresponds to the value **peter** in MD5.
### **Brute-Force Setup**
1. Send the cookie query to **Burp Intruder** and select the cookie value as the injection area.
In Payload Processing:
* add a transformation generating a hash **MD5**;
* add a prefix: `carlos:`
* encode all in **Base64**.
1. Load the password list in Payload Settings.
During the attack, an answer **200** indicates the right cookie for Carlos.
The cookie obtained is:
```bash
Y2FybG9zOjdkOGJjNWYxYThkMzc4N2QwNmVmMTFjOTdkNDY1NWRm
```
Decoding
{% code overflow="wrap" %}
```bash
echo -n "Y2FybG9zOjdkOGJjNWYxYThkMzc4N2QwNmVmMTFjOTdkNDY1NWRm" | base64 -d ;echo
```
{% endcode %}
* carlos:7d8bc5f1a8d3787d06ef11c97d4655df
By checking this hash on CrackStation, we find that the associated password is **taylor**.
---
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