> 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/access-control/user-id-controlled-by-unpredictable-guid-parameter.md).
# User ID Controlled by Unpredictable GUID Parameter
User ID Controlled by Unpredictable GUID Parameter notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
#### User ID Controlled by Parameter
This lab presents a **horizontal privilege escalation** issue on the user account page. / The particularity is that **users are identified by GUIDs**, i.e. long and random credentials, for example:
```bash
9e2f3fc0-7035-48ed-ad6d-f643690c7b9d
```
After connecting to the account **wiener:peter**, you can see your own GUID in the My account section.
#### **Recovery of GUIDs Through Publications**
By browsing the site, we find in the **visible publications** the GUIDs of other users:
* The administrator's GUID appears on one of his posts.
Similarly, we can recover the GUID from **carlos**.
```bash
?userId=5abc76d3-7763-4be9-83d1-c6181bcdf0b5
```
#### **Operation: Access to Carlos Account**
The account page is accessible via a controllable parameter:
```bash
my-account?id=5abc76d3-7763-4be9-83d1-c6181bcdf0b5
```
By simply replacing our GUID with **carlos**, we get his account:
---
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