Jimmy Li Web Developer, CTFs with redpwn and dicegang

HITCONCTF - Sandbox Escape

HITCON CTF is no joke. The challenges were crazy hard and very interesting at the same time. This first writeup will be about oShell which was a sandbox escape. This will not cover the first section of the challenge but will focus more on the sandbox escape using tcpdump and ping.

TokyoWesternsCTF - Web Exploitation

We took part in TokyoWesterns CTF this past weekened and I focused on solving the web exploitation challenges. We were able to solve the first set of angular js challenges and I learned that recaptcha gadgets are very useful. Overall, the CTF definitely deserves its high point value and it was very fun and educational.

Cross Site WebSocket Hijacking with socketio

Cross-Site WebSocket Hijacking or (CSWSH), yes the acronym is absurdly long, is a technique where an attacker can hijack a WebSocket on a targetted site and essentially send and receive messages like the victim. In this blog post, I will specifically explore how this can be done with socketio when the requests are not upgraded to actual WebSockets. In addition to explaining how this attack type works, this post will include a specific writeup for Support Chat, a CTF problem from HacktivityconCTF.

Chujowy CTF - Web Exploitation

Flaky was a web challenge with a pretty interesting attack that I didn't know about. It deals with how a HEAD request is handled internally and how that can lead to authentication problems.

RedpwnCTF in review

Over the past week, RedpwnCTF 2020 took place and I was one of the organizers of the event. I would really like to give props to my team members and additional organizers of the contest for putting together such an event.


This ctf had so many misc and forensics problems that I wasn't really interested in solving however I did finish the web problems as well as some crypto problems. The web problems were pretty trivial inspect element challenges except for the JWT attack and the XML external entitiy inclusion attack which I have written up. On the other hand I started doing cryptography problems which I find pretty interesting and have also started to build my own repository with tools for cryptography.

TJCTF - Binary Exploitation

I played tjctf with interlake high school cyber (ihscy) and it was tons of fun working with new people on interesting problems. I learned a lot of binary exploitation techniques this ctf as it was one of the first were I was both able to exploit them and focused on it instead of web. Working with Ian on some of the pwns was really fun and hopefully I'll be able to have a similar experience in the future.

IJCTF - Broken_Chrome

I didn't have much time to look at this ctf but I was able to solve one web problem. This was interesting to me because I faced some difficulties in getting my payload to work and learned some concepts about the dom.

TAMUCTF - Web Exploitation

I did two web challenges for TAMU CTF and they were mostly applications of standard attacks. The sql inejection was interesting because it was not immediately obvious that it was injectable.

HackTMQuals - Draw with us

HackTM challeneges were pretty unique and challenging. I didn't spend much time on the ctf and only was able to solve the first web challenge which exploited unicode and objects in javascript to get the flag.

WhitehatCTF - Web02

This was the second web challenge we solved in Whitehat I thought this problem was much more interesting than the first.

WhitehatCTF - Web01

I did WhitehatCTF with DiceGang this weekend and focused on the webs. We did pretty well and placed second in the quals right after perfect blue. I thought a couple of them were pretty cool but would have been much better with source. In my opinion, sourceless web ctf challenges should rarely exist.

ChristmasCTF - Web Exploitation

ChristmasCTF had some interesting problems. We started late but still did pretty well. I focused mainly on web and tried to do some of the easier pwn problems. The CTF wasn't on CTFTime but was located at https://x-mas.aleph.kr/.

ChristmasCTF - Binary Explotation

The one binary exploitation problem I tackled this CTF was solo_test which was a 64 bit binary. The problem seemed to be a standard problem yet it has been one of my first successful exploitations in competition and was a good learning experience.


This is my first blog post and I'm writting it a while after the CTF has concluded however I need to start somewhere right? I wasn't able to contribute much to this CTF as I was preparing for finals. However, I did have a great time solving and attempting what I could and it was great to work with other members of redpwn.