> 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/information-disclosure/authentication-bypass-via-information-disclosure.md).
# Authentication Bypass via Information Disclosure
Authentication Bypass via Information Disclosure notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Authentication Bypass via Information Disclosure
The application administration interface includes an authentication bypass mechanism. This is based on a custom HTTP header used by the front-end, but unknown a priori. / To solve the lab, you need to identify the name of this header, use it to bypass authentication, access the administration interface and delete user **carlos**.
**Initial access to the administration interface**
An attempt to access the admin page directly via the `/admin` route returns the following message:
> *Admin interface only available to local users*
This indicates that access is restricted to requests from the local host.
**Disclosure of information via TRACE method**
By sending an HTTP query with the `TRACE` method to `/admin`, the server returns more headers than needed.
```bash
TRACE /admin
```
Among this information, a custom header is revealed:
```bash
X-Custom-Ip-Authorization
```
This header is used by the front-end to determine if the query comes from a local user.
**Contouring authentication**
Adding the following header to a query to `/admin`:
```bash
X-Custom-Ip-Authorization: 127.0.0.1
```
the server considers the request local. / The administration interface then becomes accessible without additional authentication.
**Final Exploitation**
Once connected to the administration panel, it is possible to remove the target user by accessing the following URL:
```bash
/admin/delete?username=carlos
```
---
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