> 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/dom/dom-based-open-redirection.md).
# DOM-Based Open Redirect
DOM-Based Open Redirect notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### DOM-based Open Redirection
This lab contains an open redirection vulnerability on the DOM side. The goal is to exploit this vulnerability to redirect the victim to the exploit server.
**Vulnerable Fragment (back to blog button)**/ The action code associated with the button in the comments section is:
{% code overflow="wrap" %}
```javascript
onclick='returnUrl = /url=(https?:////.+)/.exec(location); location.href = returnUrl ? returnUrl[1] : "/"'
```
{% endcode %}
This script extracts a `URL` parameter from the current URL using a regular expression and redirects to its value if it exists; Otherwise it returns to the root (`/`).
**Operating principle**/ Simply add `&URL=` to the post URL. When the user clicks on "back to blog", the script recovers this parameter and the browser is redirected to the supplied target.
**URL examples**
{% code overflow="wrap" %}
```
https://0a9700fa04b783118073038f00bc00eb.web-security-academy.net/post?postId=1&url=https://jord4n.pro
```
{% endcode %}
* — after loading, click back to blog redirects to `https://jord4n.pro`.
For the lab (direct to the exploit server):
{% code overflow="wrap" %}
```
https://0a9700fa04b783118073038f00bc00eb.web-security-academy.net/post?postId=1&url=https://exploit-0abf00fb04aa83b480d502ca019900d1.exploit-server.net/
```
{% endcode %}
---
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