[Vinavil]

— Community CTF #02 —
Find the Flag (a sequel to Hackers's CTF)

---

FIRST 3 WINNERS WILL BE ANNOUNCED IN THIS THREAD

🏆 HerrWinston InspectorGadget Au Jus Demon

---

This is a reverse engineering challenge created and managed by Vinavil. Download the binary below and find the hidden flag.
Flag format:

Code

vibe{...}

Official Hint: strings won't save you this time.
Rules: Do NOT share hints, clues, or the answer in this thread. PM Vinavil directly with the correct flag. First 3 correct submissions win.

---

Download: crackme_02

---

Official Walkthrough

1. Open Ghidra, create a new project, and import the binary. Let the auto-analysis run with default settings.
2. Once analysis is done, open the Symbol Tree on the left and navigate to Functions -> main. Double-click to open it in the decompiler.
3. In the decompiler view you will see a loop. Inside it you will notice the input bytes being XOR'd with a constant key before being compared against an encoded byte array stored in the binary.
4. Note down the XOR key. Then open Window -> Defined Data or look in the listing view for the encoded array near the top of the function. Copy all the bytes out.
5. XOR every byte in the array with the key you found. The result is the flag in plaintext.
6. Submit

Code

vibe{...}

to Vinavil via PM.

---

This is a step up from CTF #01. More challenges are coming. Good luck.
Vibe will have more CTF challenges and competitions in the future. Also a special thanks to 7 for making this possible!

[Hackers]

Looks like this one might be a bit trickier. Anyone up for the challenge ?

:)

[HerrWinston]

I have sent u a convo message, hopefully I was right lol, my provided explanation was kind of ass, but its hopefully understandable. ^^

[InspectorGadget]

Great threads, may i suggest an official walk through is provided once 3 people have submitted the correct flag?

I've PM'd you the flag for this one :)

[Vinavil]

Great threads, may i suggest an official walk through is provided once 3 people have submitted the correct flag?

I've PM'd you the flag for this one :)

Will do great suggestion, correct flag, please provide the explanation!

[Hackers]

I have sent u a convo message, hopefully I was right lol, my provided explanation was kind of ass, but its hopefully understandable. ^^

Great threads, may i suggest an official walk through is provided once 3 people have submitted the correct flag?

I've PM'd you the flag for this one :)

Nice guys! Don't be afraid to msg Vinavil or me if you have any ideas for future CTFs too. Definitely want to keep it up and make sure ppl are having fun w/ these challenges

I don't know if you two had correct flags, I'm just glad to see ppl trying these. Vinavil will have to verify for you

[Vinavil]

Thread Update with winners, thanks for playing, the next one will be a bit harder so stay tuned!

[Hackers]

If the original DL link is broken in future, here is CTF2 file:
https://mega.nz/file/U2Nw1YoB#RI-Z14n6Hp...IHQOaE5x6c