Some of the most damaging breaches involve no exploit at all. The data simply leaks through features that work exactly as designed — because the application sends, embeds, or publishes more than it should and trusts the client to look away.
It helps to separate two related ideas:
- Content discovery (a separate lesson) is about finding files and paths a developer forgot to remove — a backup, an admin route, a
/.gitfolder. - This lesson is about data leaking through legitimate functionality. The endpoint is meant to exist, the product page is meant to render, the client bundle is meant to ship — but each one carries data it should not, and an attacker who simply looks closely can read it.
The common root cause: the application decides what to send based on what the UI shows, not on what the caller is authorised to know. A field the interface ignores is still sitting in the HTTP response.
In this lesson you will:
- Tell data exposure apart from file discovery.
- See four distinct ways normal features leak data: an over-sharing API, an outdated cross-domain technique (JSONP), a confidential detail copied to a public site, a downloadable artefact at a predictable URL, and a secret hardcoded into the shipped client.
- Work four NovaCart Sensitive Data Exposure challenges, each as its own practical.
- Name the principle that limits how much data a response should carry, and the durable server-side defences.
Estimated time: twelve to eighteen minutes.
Note on the target: these challenges span several parts of NovaCart, so the lesson opens at the home page (/vuln/nebula-search). The exact products, endpoints, and leaked values are version-dependent — confirm each against your running instance and the current challenge set before attempting. Do not assume a value from memory.
When you are ready, send the Continue signal.