> For the complete documentation index, see [llms.txt](https://ganesha-hk.gitbook.io/cybersecurity-writeups/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ganesha-hk.gitbook.io/cybersecurity-writeups/port-swigger-path-traversal-labs/lab-1.md).

# lab-1

## File Path Traversal, Simple Case

**Difficulty:** Apprentice

### Lab Description

This lab contains a path traversal vulnerability in the display of product images.

**Objective:** Retrieve the contents of the `/etc/passwd` file.

### Root Cause

The application server blindly trusts user-controlled input when constructing file paths, opening the requested file without any validation. An attacker can use traversal sequences (`../`) to walk up from the application's working directory to the filesystem root and then navigate to any file on the server.

### Exploitation

1. Access the lab and view any product page.
2. Capture the request in Burp Suite.
3. Find the URL endpoint: `GET /image?filename=36.jpg`
4. Replace the filename value with:

   ```
   ../../../../../etc/passwd
   ```
5. Send the request — the contents of `/etc/passwd` are returned in the response.

### Lesson Learned

Servers must never trust user-controlled file path inputs. A whitelist of expected filenames or a strict canonical path check must be applied before any file is opened.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://ganesha-hk.gitbook.io/cybersecurity-writeups/port-swigger-path-traversal-labs/lab-1.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.