Hey, this is Yadhu Krishna 馃憢

An undergraduate web security researcher from Kerala, India. 馃嚠馃嚦

PyCGI: From Nginx Path-Traversal to RCE; bi0s CTF 2022

This year I contributed 2 challenges to bi0s CTF (formerly InCTF Internationals). EmoLocker (Server-Side) PyCGI (Client-Side) In this post, we discuss the intended solution to PyCGI challenge. The source code of this challenge can be downloaded from here. Analysis We are provided with 2 attachments for this challenge: Dockerfile Nginx.conf Looking into the Nginx configuration, we can find that there is a potential path traversal in the /static endpoint. You can read more about this here....

<span title='2023-01-19 00:00:00 +0000 UTC'>January 19, 2023</span>&nbsp;路&nbsp;4 min&nbsp;路&nbsp;Yadhu Krishna M

Unlocking the EmoLocker: bi0s CTF 2022 - Author's Writeup

In this post, we discuss the solution to EmoLocker challenge from bi0s CTF 2022. The source code of this challenge can be downloaded from here. Analysis Upon opening the challenge link, we are presented with a lockscreen that uses emojis instead of numbers. The page has two features: register and login. Additionally, there is an admin bot, which suggests that the challenge may involve client-side concepts. The frontend of this application is developed in React....

<span title='2023-01-19 00:00:00 +0000 UTC'>January 19, 2023</span>&nbsp;路&nbsp;3 min&nbsp;路&nbsp;Yadhu Krishna M

A Timeline of Growth: Reflections on the Past, Present and Future

As I look back at my three and a half years at Amrita University and Team bi0s, I can鈥檛 help but feel a sense of nostalgia. Join me as I take a trip down memory lane, and reflect on the experiences, lessons, and achievements that have shaped me into the person I am today. 馃殞 Journey so far.. As I reflect on the past few years, I am struck by the impact that time has had on me....

<span title='2022-11-13 01:00:20 +0000 UTC'>November 13, 2022</span>&nbsp;路&nbsp;7 min&nbsp;路&nbsp;Yadhu Krishna M

A tale of HTML Injection to Account takedown at Exercism.org

About Exercism Exercism is an online platform that helps people upskill their programming skills through practice and mentoring. They are an open-source organization with over 200 GitHub repositories, thousands of contributors, and a friendly, inclusive community. I came to know about the platform in 2018 when my mentor - Vipin Pavithran asked me to improve my coding skills by practicing on Exercism. Exercism is an amazing platform to learn to code....

<span title='2022-11-05 01:00:20 +0000 UTC'>November 5, 2022</span>&nbsp;路&nbsp;3 min&nbsp;路&nbsp;Yadhu Krishna M

Good Intentions - CSAW CTF Qualifiers 2022

tl;dr Upload log configuration file and exploit path traversal to gain RCE ...

<span title='2022-10-17 11:57:25 +0000 UTC'>October 17, 2022</span>&nbsp;路&nbsp;4 min&nbsp;路&nbsp;Yadhu Krishna M