> For the complete documentation index, see [llms.txt](https://ganesha-hk.gitbook.io/offensive-security-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/offensive-security-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 by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

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

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

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.