Leak Detector - Firefox Extension

Leak Detector – Firefox Extension

Overview

Leak Detector is a proof‑of‑concept Firefox add‑on that demonstrates a hidden privacy risk: malicious websites can capture everything you type into form fields

even if you never press “Submit.” While most security tools focus on protecting data after a submission,

this extension shines a light on the moment you start typing.

Why This Matters

1. Real‑time exposure – Keystrokes are intercepted the instant they’re entered.
   
2. Silent data collection – Attackers can harvest usernames, passwords, credit‑card numbers, or any personal info without the user ever knowing.
   
3. Awareness & education – By visualising the leak, developers and security researchers can better understand the attack surface and design stronger mitigations.
   

WEBPAGE POC

https://carlostkd.ch/leak

Note: This is a POC only – the webpage does not transmit data anywhere. It simply demonstrates the vulnerability.

Installation

1. Open the Firefox Add‑Ons store.
   
2. Search for “Leak Detector”
3. Click Add to Firefox → Add.
   
4. Pin the extension.
   

Once installed, the extension icon appears next to the address bar.

Using the Extension

1. Navigate to any website with a form (e.g., a login page).
   
2. Start typing in the username or password field.
   
3. If the website is sniffing what you write soon as you starts writen the extension will show how many leaks in a Read ball