How I Earn 30000 USD Bug Bounty? Researcher Unveiled

Gokul Sudhakar - Security Researcher
Gokul Sudhakar – Security Researcher

The Indian security researcher Gokul found a critical vulnerability in a private program and earned $30,000 USD Bug Bounty.

He shared the secrets of finding Bugs, which will help to gain knowledge for new security researchers.

Gokul shared the story as follows in two-part.

PART 1:The Secrets on port 8081

As my undefined methodology on bug hunting, if I am having a bad day, I’ll just dig everything on Censys and Shodan! So I did the same thing here also. Just went to Censys and dug every IP addresses of

After digging for some time I saw this interesting IP address which have so many ports are open. 80,443,8081,8080 and so on.

So this IP was fishy particularly on ports 8080 and 8081. I noticed that this IP address is related with MongoExpress and Jenkins from the sidebar of censys. But I was still not sure about whether the IP belongs to So before exploring those ports and everything I went to SSLhopper just to check if the IP belongs to Interestingly it belongs to and also associated with many other online properties of this particular company.

So I straight up opened the port 8081 first: https://ipaddress:8081I felt that moment like the rain on a desert. THAT WAS AN EXPOSED MONGOEXPRESS PANEL WITHOUT ANY AUTHENTICATION.

Since I got free access to this panel I was able to do whatever I want including:

  • Configure existing dbs
  • Creating new db
  • Deleting existing db More and more.

Due to some severe misconfiguration I was able to access following paths too.

DB found in Mango Express Status
DB found in Mango Express Status

  • http://ip:8081/db/config/
  • http://ip:8081/db/config/system.sessions 
  • http://ip:8081/db/admin/system.users
  • http://ip:8081/db/admin/system.version
  • http://ip:8081/db/local/startup_log


Site DB Collection Doc
Site DB Collection Doc

And Most importantly I found the admin credentials from admin db in salt form and an attacker was able to edit it.

So I reported to the company immediately by explaining everything and rated as CRITICAL. And read part 2 for some real twist:

PART 2: The Gem on port 8080

So as I explained on 1st part, I was checking all the ports on this Majestic IP address. And we have completed the mysteries on port 8081. Some of you may have thought that why I tested 8081 before 8080. Only one reason: 8080 was a 404 error page and thought it will be a dead end:

HTTP Error found
HTTP Error

So my friends, if you ever come across such a 404 page, DO NOT CLOSE THE TAB AND GO BEHIND ANOTHER INSTANCE. This happened on those days when I started fuzzing for directories irrespective of the status code whether it may be 200,404 or 403. Most of the times the Gems are inside these pages.

So I started fuzzing http:ip:8080/ by using my wordlist insearch of some juicy directories using ffuf. I was not expecting something big, but only one word was 200 OK. And that was /jenkins/script

I suggest all of you to add this path to your fuzzing list.

I immediately opened that path: http://ip:8080/jenkins/script

My heart beat started increasing. Port 8081 was an open door to MongoExpress, But 8080 was something more special. It was an open door to JENKINS.

Unauthenticated me entered into this jenkins panel. There were many paths and information were available there, but not gonna talk about that now.
The main thing here is I got open access to this jenkins and more importantly the /script console was open. So the http://ip:8080/jenkins/script will take me into:

Jenkins Script Console
Jenkins Script Console

So I remembered seeing random tweets on RCE on jenkins instances on twitter. So I took twitter and searched for it as well as I read previously available jenkins rce reports on HackerOne.

So I understood this is the moment and I acted immediately. All I needed to do was inject some simple commands on this /script console:
Some commands I tried out on this console were:

“ls /”.execute().text
“ps aux”.execute().text
println “whoami”.execute().text

These commands will produce proper outputs from inside. For example if you give the println “whoami”.execute().text on script console the out will be Jenkins.
That’s it. I immediately prepared all the pocs and everything and reported to the team as report no:2. I was hoping that they will accept both as critical. But they took RCE seriously and duplicated MongoExpress exposure since a fix will be effective on both instances. But the bounty was 2X of what I expected and they surprised me with this at the midnight:

30000 USD Bounty
30000 USD Bounty

In short:

Use simple censys search like ( and

  1. Or shodan querries like this: Set-Cookie: mongo-express=” “200 OK”
  2. Add /jenkins/script to your wordlist.

Major Takeaways:

  • Never believe a 404 page.
  • Censys and Shodan are real friends.

This tutorial will help bug hunters and security researchers learn little tactics to find Bug Bounty.

You can connect with Gokul via LinkedIn.

Join Our Club

Enter your Email address to receive notifications | Join over Million Followers

Previous Article
VMware Vulnerability

VMware ESXi Zero-Day Vulnerability Found

Next Article
Google Bard Privacy

Google Warns Employees Over BARD AI Privacy Sustain

Related Posts