📊 Challenge Overview

Category	Details	Additional Info
🏆 Event	PicoCTF - 2025	Event Link
🔰 Category	Misc	🎯
💎 Points	100	Out of 500 total
⭐ Difficulty	🟢 Easy	Personal Rating: 1/10
👤 Author	Taylor McCampbell	Profile
🎮 Solves (At the time of flag submission)	2.753	solve rate
📅 Date	15-03-2025	PicoCTF - 2025
🦾 Solved By	mH4c3r0n3	Team:

📝 Challenge Information

The Rust saga continues? I ask you, can I borrow that, pleeeeeaaaasseeeee? Download the Rust code here.

🎯 Challenge Files & Infrastructure

Provided Files

Files:

•  Attached Files

🔍 Initial Analysis

First Steps

This is the second challenge in the Rust Fixme series. Here, we are also given comments that serve as hints:

• // How do we pass values to a function that we want to change?
• // Is this the correct way to pass a value to a function so that it can be changed?

Let’s proceed directly to the exploitation phase.

🎯 Solution Path

Exploitation Steps

Exploitation

The changes I made were the following:

• I changed the function signature of decrypt to accept a &mut String as the second parameter, so that the value of the string can be modified.
• The variable party_foul is now mutable (let mut party_foul = ...), because it needs to be modified inside the function.
• When passing party_foul to the decrypt function, I did so as &mut party_foul to ensure the function could modify it.

After that, I ran the program and found the flag.

🛠️ Exploitation Process

Approach

Since the procedure has already been explained, I’ll just leave the corrected file here:

•  Main

🚩 Flag Capture

Flag

picoCTF{4r3_y0u_h4v1n5_fun_y31?}

Proof of Execution

Screenshot of successful exploitation

🔧 Tools Used

Tool	Purpose
Rust	Exploit

💡 Key Learnings

Skills Improved

• Binary Exploitation
• Reverse Engineering
• Web Exploitation
• Cryptography
• Forensics
• OSINT
• Miscellaneous

📚 References & Resources

[!info]+ Additional Information

Similar Challenges

• Rust Fixme 1
• Rust Fixme 3

Learning Resources

• https://www.rust-lang.org/learn

📊 Final Statistics

Created: 15-03-2025 • Last Modified: 15-03-2025 *Author: mH4c3r0n3 • Team: *