Tools of the Trade: File permissions in Linux

As part of the Google Cybersecurity Professional Certificate, I completed a specialised module on Linux file permissions within the “Tools of the Trade: Linux and SQL” course. This module provided hands-on experience with managing and securing access to files and directories in a Linux environment — a critical skill for any cybersecurity analyst working in system hardening, incident response, or access control. An organisation needs to update the file permissions for certain files and directories within the projects directory. The permissions do not currently reflect the level of authorisation that should be given. Checking and updating these permissions will help keep their system secure. To complete this task, I performed the following tasks:
🛠️ Responsibilities

The following code demonstrates how I used Linux commands to determine the existing permissions set for a specific directory in the file system.
The first line of the screenshot displays the command I entered, and the other lines display the output. The code lists all contents of the project's directory. I used the ls command with the -la option to display a detailed listing of the file contents that also returned hidden files. The output of my command indicates that there is one directory named drafts, one hidden file named .project_x.txt, and five other project files. The 10-character string in the first column represents the permissions set on each file or directory.
The 10-character string can be deconstructed to determine who is authorized to access the file and their specific permissions. The characters and what they represent are as follows:
1st character: This character is either a d or a hyphen (-) and indicates the file type. If it’s a d, it’s a directory. If it’s a hyphen (-), it’s a regular file.

🛠️Skills Gained

Linux File and Directory Permission Management 🞄 Ownership and Group-Based Access Control 🞄
Command-Line Tools: chmod, chown, ls -l, umask 🞄 Securing System Files and Logs 🞄 Practical Application of the Least Privilege Principle

🛠️Reflection

Mastering file permissions in Linux reinforced my ability to secure operating systems at the foundational level.
This knowledge is directly applicable to real-world scenarios such as protecting sensitive data, auditing systems for misconfigurations, and maintaining secure environments in SOC and DevSecOps workflows.