Intro
Welcome to the StudSec CTF Challenges!
Some of these challenges can be quite overwhelming, especially as a beginner. So here are some quick pointers for each category as well as some general tips and tricks.
Often, a challenge can require you to encode or decode data in a certain way. One excellent tool for this is CyberChef
The Challenge name is often an indirect hint towards its contents. If your stuck it might be worth googling the name and related terms.
If your stuck, don't hesitate to ask. We all have to start somewhere, a simple question like "Hey, I'm currently looking at X, I've tried y and z. However, it doesn't seem to work." Allows others to nudge you on the right path (though don't expect others to solve the challenges for you).
Keep in mind however that this type of questioning is generally banned in competitive CTF play.
Web
Web challenges generally come in two flavors, client-side attacks and server side attacks.
For client side attacks you'll generally be attacking a different browser. For example, with xss you try to exploit other users logged into the website. These challenges can be solved by crafting a malicious website of your own and having StudBot visit it, you can do this by dming !visit <url> to the bot.
For more information about client side attacks check the following list,
https://portswigger.net/web-security/csrf
https://www.youtube.com/watch?v=EoaDgUgS6QA
For server side attacks your directly attacking the server, for this It's important to identify what's running on the server, is there a database? If so what kind? What is the server running? Php? Javascript? Answering these questions can help you target your research.
For example, if you know the server is running Flask you can look up Flask exploit or Flask exploit ctf, which might lead you to this https://book.hacktricks.xyz/network-services-pentesting/pentesting-web/flask . Additionally, looking a bit deeper into flask we see it uses the Jinja2 templating engine, which could prompt you to look up Jinja2 template injection.
For more information about server side attacks check the following list,
https://www.youtube.com/c/ippsec
https://www.youtube.com/watch?v=WWJTsKaJT_g
https://book.hacktricks.xyz
Reversing
While not exclusively the case, most reversing challenges contain a flag which you must recover. Either by passing the checks restricted or by bypassing these checks (or the flag is the check). You can use binary patching to bypass some of these checks but keep in mind the flag is intended to work on the original binary.
The best way to get started with these challenges is to throw them in a decompiler (Ghidra is recommended) and start labeling functions and variables based on their behavior. This allows you to slowly build up a picture of the binary and lets you figure out the flag.
For more information and tools check the following list,
https://ghidra-sre.org/
https://www.youtube.com/watch?v=fTGTnrgjuGA
objdump
gdb
https://www.youtube.com/watch?v=VroEiMOJPm8
Honorable mention: gdb gef extention
Crypto
Crypto challenges are generally an exceptionally difficult CTF category. They either incorporate 'made up' crypto systems or introduce a deliberate flaw in an established crypto system. In the first case your best bet is to use your imagination, check if the crypto system is similar to/matches existing ciphers (google is your friend here). In the second case, try to identify the crypto system used, generally this is given, and then do some research into it. For most major systems there will be a computerphile or live overflow video on the topic. In high level CTFs it is not uncommon to implement attacks based on research papers.
For more information check the following list,
cryptohack.org
https://www.youtube.com/watch?v=sYCzu04ftaY
https://www.youtube.com/watch?v=Rk0NIQfEXBA
PWN
PWN challenges generally require you to gain arbitrary code execution (or, in beginner challenges, change code flow). For this you nearly always get the binary (or source code), it is recommended to first reverse engineer the binary to see how it works. From there you can look for the vulnerability, for example a buffer overflow, or a use-after-free. One good first step is to run checksec on a binary to see what protections are in place.
Once you've identified your vulnerability you can start exploiting, this itself is generally a challenge, requiring you to chain code fragments and manipulate the memory to execute code.
This segment is unfortunately brief, as I am not really qualified to give advice on the topic.
For more information check the following list,
https://www.youtube.com/watch?v=iyAyN3GFM7A&list=PLhixgUqwRTjxglIswKp9mpkfPNfHkzyeN
pwntools
gdb
pwngdb or gef
Forensics
Forensics challenges are quite akin to mysteries. You get a piece of information, be it a network capture, memory dump, image or something else, and you'll need to understand what happened to recover the flag.
In this case it's a good skill to be able to filter out the noise (are the ARP requests really relevant in this network dump?), so look at filters and other items. Als make note of how information relates to each other, if you find an encrypted zip file you can probably find the password in the same email chain.
For more information check the following list,
wireshark
https://www.youtube.com/watch?v=A4_DOr7Eiqo
https://github.com/volatilityfoundation/volatility3