This is episode 2 of my Cybersecurity Roadmap series, where I learn cybersecurity in public. Last time: what cybersecurity is and the CIA triad. Today: the computer basics you need before any hacking or defending makes sense.
You cannot protect what you do not understand. So let us build the mental model.
1. Hardware: what actually runs your code
- CPU — executes instructions. Every program, including malware, is ultimately instructions for the CPU.
- RAM — fast, temporary memory. Turn the power off and it is gone. Passwords and keys sitting in RAM can be stolen while the machine runs.
- Storage (SSD/HDD) — permanent memory. Deleted files are often recoverable, because "delete" usually just marks space as reusable.
- Network card — connects the machine to other machines. Every attack from the internet arrives through it.
Security lesson: data in RAM is exposed while the machine runs, and "deleted" does not mean "gone".
2. Operating system: the boss of the machine
The OS (Windows, Linux, macOS) sits between programs and hardware. It decides:
- Which program runs when (processes)
- Who can read or change which file (permissions)
- Which program may use the network (firewall rules)
Two security ideas live here:
-
Processes: every running program is a process. Malware is just a process you did not want. Task Manager (Windows) or
ps(Linux) shows you what is running. - Users and permissions: files and programs have owners and permission levels. A normal user account cannot change system files; an administrator can. This is why you should not browse the web as administrator — any malware you run inherits your permissions.
3. Files, extensions, and why they matter
A file's extension hints at what it is — but it is only a hint:
-
.txt,.pdf,.jpg— usually data, not programs -
.exe,.bat,.sh— programs that run when opened -
.docx,.xlsx— documents that can contain macros (code!) — a classic malware carrier
Security lesson: "invoice.pdf.exe" is a program, not a PDF. Windows hides extensions by default — turn "show file extensions" on. It is a five-second change that stops a whole class of tricks.
4. The command line is not optional
A lot of security work happens in the terminal: checking processes, inspecting files, testing networks. You do not need to memorize everything — you need to be comfortable with:
- Listing files and moving between folders (
ls,cd,dir) - Reading a file (
cat,type) - Seeing what is running (
ps, Task Manager) - Checking network connections (
netstat,ss)
If the command line scares you, practice ten minutes a day. It pays off in every later episode.
5. Updates: the most boring, most important defense
Most successful attacks do not use genius zero-days. They use known vulnerabilities in unpatched software — bugs the vendor already fixed. Updating your OS, browser, and apps closes those holes. Automatic updates exist for a reason: turn them on.
Quick checklist before the next episode
- [ ] You can explain CPU, RAM, storage, and network card in one sentence each
- [ ] You know what a process is and how to list running ones
- [ ] You know why running as administrator is risky
- [ ] File extensions are visible on your machine
- [ ] Your OS and browser are up to date
Next episode: Networks — how data actually moves, and why that matters for attackers and defenders. Follow along, and tell me in the comments: Windows, Linux, or macOS — what do you learn on?
Top comments (1)
Learning in public takes guts, and you are doing it really well. I love that every section ends with a security lesson, like data in RAM being exposed while the machine runs and "deleted" not meaning gone. Tying plain hardware basics to why they matter for defense is the part most roadmaps skip, and it makes this so easy to follow.
Keeping a series going to episode 2 already shows great consistency. Which topic are you most looking forward to (or most nervous about) as the roadmap gets deeper?