You might have heard about VPN’s & Privacy Browsers leaking users’ IPs via WebRTC [1] [2]

Summary:
Got CVE-2018-6849 reserved, wrote a Metasploit Module for this issue which uses WebRTC and collects the leak private IP address, however this module may be implemented as a new library in (browser_exploit_server.rb) in MSF. #cheers What is WebRTC ?
WebRTC (Web Real-Time Communication) provides supports to web browser on a real-time communication via API.So let’s get started….There are “multiple” online services and JavaScript code available which uses WebRTC function. Even if you are using VPN’s or Privacy based browsers it leaks your actual public and private IP address.I think this is more of a privacy issue rather than security if we talk specifically in browser-based bug bounty, however, such information can help an attacker to do further recon/attack if they are in the same network.Most of the browser have WebRTC enabled by default,Mozilla Team says :This is a well-known property of webrtc – see the duplicate bug.
http://tools.ietf.org/html/draft-ietf-rtcweb-security-arch-07#section-5.4
Chrome Team says : 

We’ve already done what we plan to do, following the guidelines in https://tools.ietf.org/html/draft-ietf-rtcweb-ip-handling-04. And we offer a “Network Limiter” extension (https://chrome.google.com/webstore/detail/webrtc-network-limiter/npeicpdbkakmehahjeeohfdhnlpdklia?hl=en) to turn on more restrictive modes.

Don’t forget Facebook even they have Webkits and it is vulnerable too.
Facebook Team says :

Hi Dhiraj,

Thank you for your report. We’ve looked into your finding but determined the information being leaked is not sensitive enough to warrant a bounty. We may consider leakage of a victims referrer header, but it would have to display a full and potentially sensitive path. However, we have protections in place which prevent this from happening. Although this finding doesn’t qualify we still appreciate your time and effort sending it in.

Okay if your an android lover, you would be aware with android webkit though, The android webkit also leaks IP address as well, I tested this on Nokia 8 android 8.1.0 and the issue still exists.

Android Team says: 

The Android security team has conducted an initial severity assessment on this report. Based on our published severity assessment matrix (1) it was rated as not being a security vulnerability that would meet the severity bar for inclusion in an Android security bulletin.

Pheewww !  then what, I started targeting privacy browser and the very first browser came in my mind was DuckDuck Go which has 1,000,000+download rate in Android market and being an privacy based browser the WebRTC was enabled over there and it leaks your IP address, I reported the same to DD Go Security Team.

Duck Duck Go Team says:
Hi again Dhiraj,

Thank you for trying out the new browser and for sending this report,
including the security team. They’re currently looking into this and
I’ll let you know if any further information is needed.

There’s a similar discussion in the Firefox Focus for Android repository
on GitHub, so we’ll keep an eye on that too:
https://github.com/mozilla-mobile/focus-android/issues/609
  
Hmmmm cool, then CVE-2018-6849was assign for this issue, However I keep on taking follow up for them but they are taking too long time to patch. #Unpatched

Then I thought of creating module for this, many thanks to Brendan Coles who helped me in this and even suggested this can be used has a functionality to a HTTP library would be more useful, as it could be leveraged by existing exploits and info gathering modules.

Working of my MSF Module on DuckDuck Go Privacy Browser

In between RageLtMan also gave his thoughts that “I could actually see a benefit to this being in lib for use by things like #8648. I can inject the separate script ref in the response via the MITM mechanism, but would be cool to just generate and serve the JS directly (for any script we think will have more than 2 weeks of lifetime in browsers). Thanks for the PR”

Outcome:
So lets see, I started with private IP leak vulnerability which turned to CVE-2018-6849, which gave rise to a Metasploit module, which will in turn became a part of MSF library,

now that’s cool. Hope you like the read……