Extra Blank Lines While Pasting Exploit Code in TryHackMe AttackBox – Issue, Fix, and Alternatives

While working on TryHackMe labs using the AttackBox, I encountered a subtle but frustrating issue when pasting exploit code copied from the internet (GitHub, Exploit-DB, blogs) into terminal editors such as nano or vim.

This article documents the issue, its impact, the fix that worked, and alternative approaches that can help others facing the same problem.

The Issue

When exploit code copied from online sources was pasted into nano or vim inside the TryHackMe AttackBox, an extra blank line was automatically inserted after every line of code.

This resulted in files looking like this:

import socket

from time import sleep

import argparse


help = " Mobile Mouse 3.6.0.4 Remote Code Execution "        

To confirm the issue, the following command was used:

cat -A exploit.py        

This clearly showed empty lines ($) between every valid line of code.

Impact

• Python exploits failed or behaved unexpectedly
• Indentation-sensitive code broke
• Public PoCs became unusable
• Debugging time increased unnecessarily
• Particularly disruptive during TryHackMe labs and assessments

Root Cause

This behavior appears to be caused by a combination of:

• Browser-based clipboard handling in the TryHackMe AttackBox
• Copying formatted code from web pages
• Line-ending inconsistencies (CRLF vs LF)
• Terminal/editor paste behavior in a remote VM

Because the AttackBox is accessed through a browser, clipboard normalization is not always reliable.

Methods Tried

The following approaches were tested:

• Pasting into nano → Issue persisted
• Pasting into vim → Issue persisted
• Manual retyping → Worked, but impractical
• File inspection using cat -A → Confirmed extra blank lines

Working Fix (Recommended)

The most reliable fix was removing all empty lines using sed:

sed -i '/^$/d' exploit.py
        

Why this works:

• Matches empty lines (^$)
• Deletes them in-place
• Fast, simple, and effective in the AttackBox

After applying this fix, the exploit executed correctly.

Alternative Solutions

1. Download Exploits Instead of Copy-Paste (Best Practice)

wget <exploit-url>        

This avoids clipboard issues entirely and is the cleanest approach in TryHackMe labs.

2. GUI Editors (Pluma / Sublime Text) – Limited Alternative

Tools like Pluma or Sublime Text can also be used to paste and clean exploit code without newline issues.

However:

• They are ineffective for terminal-based workflows
• Exploitation, debugging, and execution still happen in the shell
• Frequent switching between GUI editor and terminal slows down workflow

While this is a possible workaround, it is not practical during real-world pentesting or TryHackMe labs, where terminal-centric operations are essential.

Open Question

Are there any AttackBox-specific configurations, editor settings, or terminal options that permanently prevent this newline issue when pasting exploit code copied from the internet?

If you’ve found a cleaner or more permanent solution, it would be great to learn from your experience.

Conclusion

This is a common but often overlooked issue when using the TryHackMe AttackBox. While small, it can completely break exploit execution. The sed fix proved to be the fastest and most reliable solution, with several alternatives depending on workflow preference.

Hopefully, this saves others time during labs and assessments.