> 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/xss/cookie-theft-via-xss.md).
# Cookie Theft via XSS
Cookie Theft via XSS notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Exploiting Cross-site Scripting to Steal Cookies
The lab has a XSS vulnerability stored in the blog comment function. A victim user consults the comments after publication. The educational objective is to understand how a client-side injection can lead to the exfiltion of session information and how to protect it.
The comment field does not apply sufficient encoding or escape for user input, allowing the browser to inject content when another user displays the page.
```javascript
```
We use `fetch` to make requests:
```javascript
```
The request arrives on the listening infrastructure.
We send the session cookie:
```javascript
```
```
secret=QplRMu1d8Cvif8Ai7En7j3ADRb0DZxa0;
session=sw0gW8IuyBITTD0ChgDydWcmuFx5J79D
```
We then replace the session cookie.
You can also encode the content in base64 before sending:
```javascript
```
---
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