Tags: deobfuscating javascript
Rating:
# Open your eyes 1/5
## Background
Sometimes there is more than meets the eye. Be clever and collect the 5 flags. Some are easy, some are hard.
Access the challenge here : [https://heroctf.joinopencyber.tech/](https://heroctf.joinopencyber.tech/)
Format : Hero{J...}
Author : OPENCYBER
## Find the flag
**In this challenge, we can access the challenge machine in [https://heroctf.joinopencyber.tech/](https://heroctf.joinopencyber.tech/):**
**Home page:**
In here, we can "LOGIN AS A GUEST" or "LOGIN".
**Let's login as a guest first:**
In here, we can send some messages to someone.
Since **JavaScript is a client-side language**, we can poke around in the source code.
**To do so, I'll open up the "Debugger" tab:**
As you can see, **it has 2 main JavaScript files: `app.js`, `main.js`.**
**But before we look at the `main.js`, I found something weird in `app.js`:**
Hmm... I can see the flag format! (`Hero{.*}`)
Now, we can **dynamically deobfuscate** those JavaScript code!
> Note: You can read my recent "PwnMe Qualifications : “8 bits”"'s web challenge writeup: [Beat me!](https://siunam321.github.io/ctf/PwnMe-2023-8-bits/Web/Beat-me/). It's a web challenge that exploiting client-side game and dynamically deobfuscating JavaScript code.
**That being said, let's add a breakpoint to variable `_0x2e08e0`:**
**Then refresh the page:**
**Next, click the "Step Over" button twice:**
Nice! We found half of the flag:
However, we can't step over again, as the if statement in line 31 won't get passed.
**If you look closely, variable `_0x45a81e` is function `_0x4cbad0()`:**
**So, we can concatenate the full flag via variable `_0x45a81e`!**
- **Flag: `Hero{J@v@Scr!pt_f!l3s_R_alway$_Nic3_t0_Gr@b}`**
## Conclusion
What we've learned:
1. Dynamically Deobfuscating JavaScript Code
